Removal of biogenic elements, polychlorinated diphenyls and heavy metals during the biological final treatment of waste-waters.

Weber K, Prokes B, Livansky K, Kredl F, Beryl I.

Algae were cultivated in the effluents from a treatment plant processing communal sewage and waste-water from a large-scale hoggery. The content of nitrogen. phosphorus and also COD and BOD were estimated in the effluent before and after cultivation of algae. It was found that the removal of nitrogen and phosphorus by Chlamydomonas geitleri from the effluent was optimal at highest at the high effluent concentrations while the purification efficiency in relation to PCD content depends on algae used.

PMID: 6174027 [PubMed - indexed for MEDLINE]

Speciation of heavy metals in environmental water by ion chromatography coupled to ICP-MS.

Ammann AA.

Swiss Federal Institute for Environmental Science and Technology (EAWAG), Dubendorf. [email protected]

Biogenic (e.g. phytochelatins, porphyrins, DOM) as well as anthropogenic (e.g. NTA, EDTA, phosphonates) chelators affect the mobility and cycling of heavy metals in environmental waters. Since such chelators can form strongly bound anionic heavy metal complexes that are stable and highly mobile, anion-exchange chromatography coupled to ICP-MS was investigated. A narrow bore HPLC system was connected to a micro concentric nebuliser for in-line sample introduction. A new chromatographic procedure based on a synthetic hydrophilic quaternary ammonium anion exchanger in combination with nitrate as a strong eluent anion, and gradient elution, provided high separation selectivity and a large analytical window. Low detection limits (nmol L(-1)) were achieved by on-column matrix removal and sample preconcentration. This allowed the method to be successfully applied to different environmental research areas. In ecotoxicological studies of heavy metal effects on algae low concentrations of metal EDTA complexes were determined in nutrient solutions without interference from high (buffer) salt concentrations. In groundwater, infiltrated by a polluted river, mobile metal EDTA species were observed. In river water of different pollution levels beside CuEDTA other anionic Cu-complexes were found in nmol L(-1) concentrations.

PMID: 11939532 [PubMed - in process]

Algae columns with anodic stripping voltammetric detection.

Kubiak WW, Wang J, Darnall D.

The use of silica-immobilized algal cells for on-line column separation in conjunction with continuous monitoring of trace metals is described. Algae-silica preparations are highly suitable for flow analysis as they couple the unique reactivity patterns and high binding capacity of algal biomass with the hydrodynamic and mechanical features of porous silica. Such advantages are illustrated by using on-line anodic stripping voltammetry and the alga Chlorella pyrenidosa. Selective and exhaustive removal of interfering constituents circumvents common problems such as overlapping peaks and intermetallic effects. Effects of flow rate, pH, operation time, and other variables are reported. The system is characterized by high durability, simplicity, and economy and offers an attractive alternative to prevalent columns used for flow analysis.

PMID: 2719260 [PubMed - indexed for MEDLINE]

Biosorption of nickel in complex aqueous waste streams by cyanobacteria.

Corder SL, Reeves M.

Engineering Development Section, Oak Ridge National Laboratory, TN.

A study was undertaken to determined if a suitable biosorbent could be found for removal of nickel at low concentrations (< 20 parts per million [ppm]) from a chemically complex wastewater effluent generated by electroplating operations. Algae and cyanobacteria were chosen as candidate biosorbent materials because they are easy to grow and they have the ability to withstand processing into biosorbent materials. Several species were screened for nickel-biosorption capacity initially, and three species of cyanobacteria were selected for further study based on their performance in the scoping tests. When compared to live controls, autoclaving improved the binding capacities of all three species, but usually biosorption data from experiments with live cells were more consistent. None of the three species was able to bind nickel efficiently in actual effluent samples. Further experimentation indicated that sodium ions, which were present in high concentrations in the effluent, were interfering with the ability of the cells to bind nickel. Adsorption isotherm plots for biosorption of nickel by two species of Anabaena in NiCl2-deionized water solutions were prepared.

PMID: 8010774 [PubMed - indexed for MEDLINE]

Biosynthesis of vicinal dihydroxy fatty acids in the red alga Gracilariopsis lemaneiformis: identification of a sodium-dependent 12-lipoxygenase and a hydroperoxide isomerase.

Hamberg M, Gerwick WH.

Department of Physiological Chemistry, Karolinska Institutet, Stockholm, Sweden.

Biosynthesis of the vicinal diol fatty acid (12R,13S)-dihydroxy-(5Z,8Z,10E,14Z)-eicosatetrae noic acid from arachidonic acid was studied in preparations of the red alga Gracilariopsis lemaneiformis. The transformation consisted of initial 12-lipoxygenase-catalyzed oxygenation of arachidonic acid into (12S)-hydroperoxy-(5Z,8Z,10E,14Z)-eicosatetraeno ic acid followed by hydroperoxide isomerase-catalyzed conversion of the hydroperoxide into (12R,13S)-dihydroxyeicosatetraenoic acid. Short time incubations and trapping experiments with glutathione peroxidase revealed that (12S)-hydroperoxyeicosatetraenoic acid existed as a free intermediate in the overall conversion. The 12-lipoxygenase was mainly present in the soluble fraction of homogenate of G. lemaneiformis. Further, gel filtration experiments showed that the soluble 12-lipoxygenase was a protein having a molecular weight of 84,000-89,000. The enzymatic activity of 12-lipoxygenase isolated by gel filtration was weak; however, addition of 0.8-1 M sodium chloride to such desalted enzyme increased the activity 20-fold. Experiments with different salts revealed that sodium ion was specifically responsible for the stimulatory effect. Hydroperoxide isomerase was about equally distributed between the high speed supernatant and particulate fractions. Gel filtration of hydroperoxide isomerase present in the soluble fraction showed two peaks of activity corresponding to proteins having molecular weights of 220,000 or greater, and 40,000-45,000. The stereochemical course of the biosynthesis of vicinal diol fatty acids was determined using stereospecifically deuterated 6,9,12-octadecatrienoic acids. The 12-lipoxygenase-catalyzed reaction consisted of antarafacial hydrogen removal and oxygen insertion, whereas the hydroperoxide isomerase catalyzed an intramolecular oxygenation which occurred with retention of the configuration of the carbon atom hydroxylated.

PMID: 8342944 [PubMed - indexed for MEDLINE]

Regulation of Chlorella nitrate reductase: control of enzyme activity and immunoreactive protein levels by ammonia.

Zeiler KG, Solomonson LP.

University of South Florida College of Medicine, Department of Biochemistry and Molecular Biology, Tampa 33612.

Nitrate reductase catalyzes the initial step in the conversion of nitrate to organic nitrogen and is thought to be repressed by ammonia and induced by nitrate. Induction by nitrate and repression by ammonia were studied by following changes in NADH:nitrate reductase and the associated partial activities NADH:cytochrome c reductase and methylviologenr:nitrate reductase. Immunoreactive protein was assessed by enzyme-linked immunosorbent assay and immunoblotting. Molybdenum cofactor levels were investigated using the nit-1 complementation assay as well as fluorescence of the oxidized cofactor. The results indicate that the NADH:cytochrome c reductase activity is "induced" faster than the nitrate-reducing activity and suggest that incorporation of the molybdo-pterin cofactor may be rate limiting in the expression of activity. Molybdenum cofactor levels are significantly elevated in nitrate-treated cells. Under "repressing" conditions all activities decreased at approximately the same rate. A more rapid conversion of the enzyme to a reversibly inactive form also occurred under these conditions. Changes in immunoreactive protein levels correlated most closely with NADH:cytochrome c reductase activity but appeared to increase faster during induction and decrease slightly slower during repression than the enzyme activities. Removal of exogenous ammonia results in the appearance of nitrate reducing activity, as well as immunoreactive protein (derepression). Studies using protein and RNA synthesis inhibitors indicated that de novo synthesis is required for nitrate reductase induction and were in agreement with the results of the immunoreactive studies.

PMID: 2916847 [PubMed - indexed for MEDLINE]

Effects of Ca2+ on phytoalexin induction by fungal elicitor in soybean cells.

Stab MR, Ebel J.

Biologisches Institut II der Universitat Freiburg, West Germany.

A glucan elicitor from the cell walls of the fungus Phytophthora megasperma f.sp. glycinea caused increases in the activities of the phytoalexin biosynthetic enzymes, phenylalanine ammonia-lyase and chalcone synthase, and induced the production of the phytoalexin, glyceollin, in soybean (Glycine max) cell suspension cultures when tested in culture medium containing 1.2 mmol/liter Ca2+. Removal of extracellular Ca2+ by treatment with ethylene glycol bis(beta-aminoethyl ether)-N, N'-tetraacetic acid followed by washing the cells with Ca2+-free culture medium abolished the elicitor-mediated phytoalexin response. This suppression was largely reversed on readdition of Ca2+. Elicitor-mediated enhancement of biosynthetic enzyme activities and accumulation of glyceollin was strongly inhibited by La3+; effective concentrations for 50% inhibition were (mumol/liter) 40 for phenylalanine ammonia-lyase, 100 for chalcone synthase, and 30 for glyceollin. Verapamil caused similar effects only at concentrations higher than 0.1 mmol/liter, whereas trifluoperazine and 8-(diethylamino)-octyl-3,4,5-trimethoxybenzoate did not affect enzyme induction by the elicitor in the concentration range tested. Uptake of alpha-amino isobutyric acid into soybean cells, which was rapidly inhibited in the presence of the glucan elicitor, was not affected by La3+ nor was uptake inhibition by the elicitor relieved by La3+. The Ca2+ ionophore, A23187, enhanced phytoalexin biosynthetic enzyme activities and glyceollin accumulation in a dose-dependent manner, with 50% stimulation (relative to the elicitor) occurring at about 5 mumol/liter. The results suggest that the glucan elicitor causes changes in metabolite fluxes across the plasma membrane of soybean cells, among which changes in Ca2+ fluxes appear to be important for the stimulation of the phytoalexin response.

PMID: 3116938 [PubMed - indexed for MEDLINE]

Reclamation of wastewater for polyculture of freshwater fish: bioassays using Chlorella and Gambusia.

Liang Y, Wong MH.

Institute for Natural Resources and Waste Management and Department of Biology, Hong Kong Baptist University, Kowloon Tong, Hong Kong, P. R. China.

The feasibility of using the secondary effluents from two sewage treatment plants in Hong Kong (Yuen Long and Shek Wu Hui) for fish culture was assessed. Total ammonia contents in the two sewage effluents surpassed the level of 2 mg L(-1) recommended for wastewater fish culture. The two sewage effluents both needed essential elements for supporting algal Chlorella vulgaris growth, whereas only sewage effluent from Yuen Long had contaminants at toxic levels. Total ammonia in water explained more than 80% variations of toxicity of water samples to Gambusia patruelis, mosquito fish, according to regression analysis. Removal of ammonia from the sewage effluent is necessary before being used for fish culture. In addition, the rather high levels of heavy metals (Cu, Zn, Cd) in the effluent should be closely monitored.

PMID: 11031312 [PubMed - indexed for MEDLINE]

Toxicity to estuarine organisms of leachates from chromated copper arsenate treated wood.

Weis P, Weis JS, Coohill LM.

Department of Anatomy, New Jersey Medical School, Newark 07103.

The effects of chromated copper arsenate (CCA), used for treating wood in docks, pilings, and bulkheads, were studied in several estuarine organisms. Leaching of metals from treated wood into sea water was assayed by atomic absorption spectrophotometry. Fiddler crabs (Uca pugilator) were subjected to limb removal and were placed in containers with treated wood of various sizes or control wood. Limb regeneration rate was retarded in a dose-dependent fashion and mortality occurred with the treated wood, reaching 100% in the tank with the largest piece of wood. Embryos of the mummichog (Fundulus heteroclitus) were allowed to develop in culture dishes in which CCA-treated or untreated wood was soaking. Mortality was noted in the dishes with treated wood and to a smaller extent in those with untreated wood. Containers containing CCA-treated wood, control wood, or no wood were stocked first with the alga Ulva lactuca, the snails (Nassarius obsoletus). Chlorophyll content of the algae was reduced with the treated wood within a few days, and snails with the treated wood became moribund and died within a few days. In the controls containing untreated wood or no wood, no such effects were seen. Studies with individual or combination of two or three of the metals with snails and algae indicated that the copper was primarily responsible for the snail mortality and algal bleaching seen in the treated wood experiments. In all experiments, the toxicity of the wood decreased over time; when the experiments were repeated with the same pieces of wood, effects were diminished.

PMID: 1996903 [PubMed - indexed for MEDLINE]

Mercury uptake and removal by Euglena gracilis.

Devars S, Aviles C, Cervantes C, Moreno-Sanchez R.

Departamento de Bioquimica, Instituto Nacional de Cardiologia, Mexico. [email protected]

The uptake and removal of mercury (added as HgCl2) from the culture medium by Euglena gracilis was studied. In cultures initiated in the light, cells accumulated a small fraction of the added heavy metal (5-13%). Mercury was both biologically and nonbiologically volatilized, and cell growth was partially inhibited; under these conditions the glutathione content was 3.2 nmol/10(6) cells. In contrast, in cultures initiated in the dark, mercury uptake by cells was two to three times higher, biological volatilization remained unchanged and nonbiological volatilization and growth were negligible; the glutathione content diminished to 1.4 nmol/10(6) cells. Biological mercury volatilization depended on cell density and metal concentration, but was light-independent. Thus, volatilization of mercury by Euglena appeared not to be an effective mechanism of resistance, whereas a high intracellular level of glutathione and a low mercury uptake seemed necessary for successful tolerance.

PMID: 11041348 [PubMed - indexed for MEDLINE]

The carboxyl modifier 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide (EDC) inhibits half of the high-affinity Mn-binding site in photosystem II membrane fragments.

Preston C, Seibert M.

Photoconversion Research Branch, Solar Energy Research Institute, Golden, Colorado 80401.

The diphenylcarbazide(DPC)/Mn2+ assay [Hsu, B.-D., Lee, J.-Y., & Pan, R.-L. (1987) Biochim. Biophys. Acta 890, 89-96] was used to assess the amount of the high-affinity Mn-binding site in manganese-depleted photosystem II (PS II) membrane fragments from spinach and Scenedesmus obliquus. The assay mechanism at high DPC concentration was shown to involve noncompetitive inhibition of only half of the control level of DPC donation to PS II by micromolar concentrations of Mn at pH 6.5 (i.e., one of two DPC donation sites is inhibited). At low DPC concentration both DPC and Mn2+ donate to PS II additively. Treatment with the carboxyl amino acid modifier 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide (EDC) inhibited half of the high-affinity Mn-binding site in spinach and Scenedesmus WT PS II membranes and all of the available site in Scenedesmus LF-1 mutant PS II membranes. A similar EDC concentration dependence was observed in all cases. Addition of 2 mM MnCl2 to the 10 mM EDC modification buffer provided complete protection for the Mn-binding site from modification. This protection was specific for Mn2+; six other divalent cations were ineffective. We conclude that EDC modifies that half of the high-affinity Mn-binding site that is insensitive to the histidine modifier diethyl pyrocarbonate (DEPC) [Seibert, M., Tamura, N., & Inoue, Y. (1989) Biochim. Biophys. Acta 974, 185-191] and directly affects ligands that bind Mn. The effects of EDC and DEPC that influence the high-affinity site are mutually exclusive and are specific to the lumenal side of the PS II membrane. Removal of the two more loosely bound of the four functional Mn from PS II membranes uncovers that part of the high-affinity site associated with carboxyl but not histidyl residues. We suggest that carboxyl residues on reaction center proteins are associated with half of the high-affinity Mn-binding site in PS II and are involved along with histidine residues in binding Mn functional in the O2-evolving process.

PMID: 1911747 [PubMed - indexed for MEDLINE]

Composition and structure of zinc-deficient Euglena gracilis chromatin.

Stankiewicz AJ, Falchuk KH, Vallee BL.

The histone content of zinc-deficient (-Zn) Euglena gracilis decreases while, concomitantly, DNA content increases and the transcription rate is reduced markedly [Mazus, B., Falchuk, K. H., & Vallee, B. L. (1983) Biochemistry (in press); Falchuk, K. H., Fawcett, D. W., & Vallee, B. L. (1975) J. Cell Sci. 17, 57-78]. The effects on major constituents of the genome have been examined by studying the rate and extent of hydrolysis of +Zn and -Zn chromatin by micrococcal nuclease, DNase I, or DNase II. The size of hydrolyzed DNA fragments suggests similarity of the +Zn E. gracilis chromatin organization to that of other eukaryotes. The major protein constituent of -Zn chromatin is a polypeptide of less than 3000 daltons whose electrophoretic mobility differs from that of any known histone components of chromatin, the latter described elsewhere (K. H. Falchuk et al., unpublished results). This protein profoundly affects the structure of -Zn chromatin, which is about 10-30-fold more resistant to micrococcal nuclease hydrolysis than +Zn chromatin. Moreover, the resultant DNA fragments [2000 base pairs (bp)], are much larger than those of +Zn cells. Under conditions which hydrolyze +Zn chromatin into DNA fragments smaller than 50 bp, only 50% of -Zn chromatin is digested into fragments less than 2000 bp, i.e., in the range of those expected for oligonucleosomes. Removal of the low molecular weight protein from -Zn chromatin reverses its enhanced resistance to nucleolysis and results in extensive hydrolysis. Conversely, addition of the low molecular weight protein to +Zn chromatin increases the resistance of this complex to digestion.(ABSTRACT TRUNCATED AT 250 WORDS)

PMID: 6228250 [PubMed - indexed for MEDLINE]

An integrated algal sulphate reducing high rate ponding process for the treatment of acid mine drainage wastewaters.

Rose PD, Boshoff GA, van Hille RP, Wallace LC, Dunn KM, Duncan JR.

Gold Fields Biotechnology Laboratory, Rhodes University, Grahamstown, South Africa.

Acid mine drainage pollution may be associated with large water volume flows and exceptionally long periods of time over which the drainage may require treatment. While the use and role of sulphate reducing bacteria has been demonstrated in active treatment systems for acid mine drainage remediation, reactor size requirement and the cost and availability of the carbon and electron donor source are factors which constrain process development. Little attention has focussed on the use of waste stabilisation ponding processes for acid mine drainage treatment. Wastewater ponding is a mature technology for the treatment of large water volumes and its use as a basis for appropriate reactor design for acid mine drainage treatment is described including high rates of sulphate reduction and the precipitation of metal sulphides. Together with the co-disposal of organic wastes, algal biomass is generated as an independent carbon source for SRB production. Treatment of tannery effluent in a custom-designed high rate algal ponding process, and its use as a carbon source in the generation and precipitation of metal sulphides, has been demonstrated through piloting to the implementation of a full-scale process. The treatment of both mine drainage and zinc refinery wastewaters are reported. A complementary role for microalgal production in the generation of alkalinity and bioadsorptive removal of metals has been utilised and an Integrated 'Algal Sulphate Reducing Ponding Process for the Treatment of Acidic and Metal Wastewaters' (ASPAM) has been described.

PMID: 10022068 [PubMed - indexed for MEDLINE]

Removal of heavy metals by two free floating aquatic macrophytes.

Mallick N, Shardendu, Rai LC.

Centre of Advanced Study in Botany, Banaras Hindu University, Varanasi, India.

A concentration-dependent decrease in biomass, protein, RNA, DNA, and nutrient (NO3(-) and PO4(3-)) uptake of Lemna minor and Azolla pinnata by Cr, Ni, and Zn was detected. Cr was found to exert maximum toxicity followed by Ni and Zn. Metal uptake was dependent on time and concentration of metal in the external medium. Both the macrophytes, however, showed preference for Zn followed by Ni and Cr. The uptake kinetics also revealed a low Vmax and high Km for Cr. L. minor was more efficient in accumulating Zn and Cr than A. pinnata in Ni. Compared to immobilized algae and bacterial capsules the test macrophytes showed a greater efficiency for metal removal.

PMID: 8988809 [PubMed - indexed for MEDLINE]

Removal of Cu and Ni by free and immobilized microalgae.

Wong MH, Pak DC.

Department of Biology, Hong Kong Baptist College, Kowloon.

The present investigation evaluated the effectiveness of Chlorella cells in concentrating Cu and Ni in their cells and thereby removing the two metals from solution. The removal efficiency of the two metals by free and immobilized algal cells were further studied. (1) Four types of Chlorella cells, namely Chlorella pyrenoidosa (26) (from Carolina Biological Supplies Company), Chlorella HKBC-1 and-2 (isolated from a polluted stream receiving wastewater from several electroplating factories) and Chlorella HKBC-3 (from a clean water pond) were subjected to different concentrations of Cu and Ni accordingly. It was revealed that Chlorella HKBC-1 was the most tolerant species to Cu and Ni as reflected by their highest values of 48 h and 96 h "Highest no effect concentrations" (The highest concentration of the tested substance that does not inhibit the growth rate of the alga: Cu 2 and Ni 10 mg/l at 48 h, Cu 2 and Ni 5 at 96 h). This was followed by C. pyrenoidosa (26) and then C. HKBC-2 while C. HKBC-3 had the lowest tolerance to the two metals (Cu 0.5 and Ni 2 at 48 h; Cu 0.5 and Ni 1 mg/l at 96 h). (2) It was further revealed that C. HKBC-1 had higher concentration factors and removal efficiencies of Ni (734-963 mg/l, 16.3-18.7%) and C. HKBC-2 had higher concentration factors and removal efficiencies of Cu (2316-2839 mg/l, 53.7-66%) when exposed to lower concentrations of Cu (0.5, 1 and 2 mg/l) and Ni (5, 10 and 13 mg/l). (3) By treating the free and immobilized algal cells (algal cells entrapped in alginate beads) with different concentrations of Cu and Ni, it was observed that free cells had higher concentration factors and removal efficiencies when compared with immobilized cells (free cells: Cu 1577-3056 mg/l, 24.2-71.4%; Ni 355-849 mg/l, 4.8-18.7%; immobilized cells: Cu 453-935 mg/l, 13.9-53.2%; Ni 244-486 mg/l, 3.2-11.9%).

PMID: 1642794 [PubMed - indexed for MEDLINE]

Microalgae as bioabsorbents for treating mixture of electroplating and sewage effluent.

Chan SS, Chow H, Wong MH.

Department of Biology, Hong Kong Baptist College, Kowloon.

The effectiveness of copper and nickel uptake by microalgae grown in the mixture of electroplating effluent and sewage was studied. The results showed that a high percentage of copper removal (68.1%-88.2%) was achieved by Chlorella pyrenoidosa (strain No. 26) reared in the mixture of 90% electroplating effluent and 10% raw sewage during the first 3 days despite the fact that cell growth was inhibited. Similar results were also obtained by using Chlorella HKBC-C3, another species collected from one of the heavy metal polluted sites in Hong Kong, isolated and cultured in the Biology Department. There was no significant difference (P greater than 0.05) in the removal of copper and nickel from the effluent between these 2 algal species. However, it was noted that removal of nickel from the mixture by the two species were comparatively lower (less than 20%) than the removal of copper (greater than 68%).

PMID: 1764214 [PubMed - indexed for MEDLINE]

Heavy metal removal by microalgae.

Travieso L, Canizares RO, Borja R, Benitez F, Dominguez AR, Dupeyron R, Valiente V.

Department of Environmental Pollution Studies (DECA), National Center for Scientific Research (CNIC), Post Office Box 6990, La Habana, Cuba.

PMID: 9933311 [PubMed - indexed for MEDLINE]

Heavy metal binding and removal by phormidium.

Wang TC, Weissman JC, Ramesh G, Varadarajan R, Benemann JR.

Harbor Branch Oceanographic Institution, Inc., Fort Pierce, FL 34946, USA.

PMID: 9595189 [PubMed - indexed for MEDLINE]

The effects of calcium deficiency on the electrical activity of Nitella flexilis.

van Netten C, Belton P.

Calcium chelators such as ethylenediaminetetraacetic acid and sodium citrate produce repetitive activity and prolong the spike of internodal cells of Nitella flexilis. Removal of Ca2+, Mg2+, Na+, and K+ from the outside of the cell by washing the preparation with Tris propionate or Tris chloride hyperpolarizes the cells but does not initiate repetitive activity or increase the duration of the spike appreciably. It was concluded that cell-bound Ca2+ controls the threshold for stimulation and the duration of the spike, and that the removal of Ca2+ from the cell membrane, either by chelation or displacement, changes the normal behaviour of the cell by altering its permeability to some other ion or ions.

PMID: 411556 [PubMed - indexed for MEDLINE]

Performance of different microalgal species in removing nickel and zinc from industrial wastewater.

Chong AM, Wong YS, Tam NF.

Department of Biology and Chemistry, City University of Hong Kong, Kowloon, Hong Kong SAR, People's Republic of China.

A series of batch experiments was conducted to compare the ability of 11 microalgal species of the same cell density in removing nickel (Ni) and zinc (Zn) from synthetic wastewater. These included Chlorella vulgaris (commercially available), Chlorella sorokiniana and Scenedesmus quadricauda (isolates from polluted water of Wuhan, China), and eight different isolates from Hong Kong. The Wuhan isolate of Scenedesmus removed most Ni, probably due to its large biomass. Nickel concentration was reduced from an initial 30 to 0.9 mg/l after 5 min (97% Ni removal), and further declined to 0.4 mg/l after 90 min of treatment. In wastewater containing 30 mg/l Ni and 30 mg/l Zn, more than 98%, Ni and Zn were removed simultaneously at the end of 5 min treatment, indicating that the presence of Zn in wastewater did not affect Ni removal by this Scenedesmus isolate. The second most effective species for Ni removal was an isolate, tentatively identified as Chlorella miniata, Ni concentration was reduced to 10 mg/l after 90 min, and was only slightly interfered by the presence of Zn. In terms of metal removal per unit biomass or unit surface area of algal cells, C. miniata was the best species in removing Ni and Zn. At the other extreme, one Hong Kong isolate (Synechocystis sp.) did not remove any Ni and only achieved 40% Zn removal. Performance of the other isolates was comparable with the commercial C. vulgaris, less than 50% Ni was removed after 5 h of treatment and Ni removal was significantly reduced by the presence of Zn. All algae tested were found to be viable, showing these 11 species could tolerate a mixture of 30 mg/l Ni and 30 mg/l Zn in wastewater.

PMID: 10819208 [PubMed - indexed for MEDLINE]

Model reactor for photocatalytic degradation of persistent chemicals in ponds and waste water.

Franke R, Franke C.

[email protected]

A laboratory scale flow-through model reactor for the degradation of persistent chemicals using titanium dioxide (TiO2) as photocatalyst immobilized on glass beads is presented. In the test system with a volume of 18 L contaminated water is pumped to the upper part of the floating reactor and flows over the coated beads which are exposed to UV-radiation. The degradation of two dyes of different persistence was investigated. Primary degradation of methylene blue did not fit a first order kinetic due to coincident adsorption onto the photocatalyst and direct photolysis, resulting in a half-life of 6 h. A filtrate of a green algae suspension accelerated the colour removal. In contrast, reactive red 2 was degraded only by photocatalysis; neither adsorption nor direct photolysis led to a colour removal. The course of primary degradation followed a first order kinetic with a half-life of 18 h and a rate constant of 0.04 h-1. Analysis of the degradation products indicated mineralization by detection of NO2- and NO3-, accompanied by a decrease of pH and an increase of conductivity. A successful adaptation of the model reactor (scale 1:10) to dimensions required for surface waters and waste water treatment plants would be a cost-efficient and environmentally sustainable application of photocatalysis for the treatment of industrially polluted water and could be of relevance for third world countries, particularly those favoured by high solar radiation.

PMID: 10633546 [PubMed - indexed for MEDLINE]

Transformation of four pathogenic Phytophthora spp by microprojectile bombardment on intact mycelia.

Bailey AM, Mena GL, Herrera-Estrella L.

Departamento de Ingenieria Genetica de Plantas, Centro de Investigacion y de Estudios Avanzados (CINVESTAV), Guanajuato, Mexico.

Phytophthora capsici, P. citricola, P. cinnamomi and P. citrophthora were transformed without the removal of cell walls by particle acceleration with plasmids containing the beta-glucuronidase gene and hygromycin B resistance. Transformants were detected by histochemical and fluorometric beta-glucuronidase assays and confirmed by Southern-blot hybridization. It was found that the promoter of a plant virus is functional in Phytophthora. In addition, a method was designed to visually identify homogeneous transformed colonies, derived from zoospores of transformed multinucleated Phytophthora mycelia, based on blue color development on plates containing X-Gluc.

PMID: 8428382 [PubMed - indexed for MEDLINE]

Removal of Pb(2+) by biomass of marine algae.

Hamdy AA.

Microbial and Natural Products Chemistry Department, National Research Centre, Dokki, Cairo, Egypt.

New biosorbent material derived from ubiquitous marine algae has been examined in packed-bed flow for Pb(2+) removal through sorption columns. Mixed biomass of marine algae has been used, consisting of representative species of the following algae: Ulva lactuca (green algae), Jania rubens (red algae), and Sargassum asperifolium (brown algae). A mixture of these three species showed a promising removal capacity for Pb(2+) from aqueous solution. Lead uptake up to 281.8 mg/g dry algal mixture was observed. Equilibrium was achieved after 120 min. No significant effect of changing the flow rate on the removal capacity was noticed. It was found that Langmuir model expresses the system at pH 4. Mineral acids exhibited good elution properties (a mean of 93%) for recovery of sorbed biomass ions as compared with the tested alkalies (about 60%).

PMID: 10977889 [PubMed - indexed for MEDLINE]

Cell wall biogenesis in Oocystis: experimental alteration of microfibril assembly and orientation.

Montezinos D, Brown RM Jr.

Cell wall biogenesis in the unicellular green alga Oocystis apiculata has been studied. Under normal growth conditions, a cell wall with ordered microfibrils is synthesized. In each layer there are rows of parallel microfibrils. Layers are nearly perpendicular to each other. Terminal linear synthesizing complexes are located in the plasma membrane, and they are capable of bidirectional synthesis of cellulose microfibrils. Granule bands associated with the inner leaflet of the plasma membrane appear to control the orientation of newly synthesized microfibrils. Subcortical microtubules also are present during wall synthesis. Patterns of cell wall synthesis were studied after treatment with EDTA and EGTA as well as divalent cations (MgSO4, CaSO4, Cacl2). 0.1 M EDTA treatment for 15 min results in the disassociation of the terminal complexes from the ends of microfibrils. EDTA-treated cells followed by 15 min treatment with MgSO4 results in reaggregation of the linear complexes into a paired state, remote from the original ends to which they were associated. After 90 min treatment with MgSO4, normal synthesis resumes. EGTA and calcium salts do not affect the linear complexes or microfibril orientation. Treatments with colchicine and vinblastine sulphate do not depolymerize the microtubles, but the wall microfibril orientation is altered. With colchicine or vinblastine, the change in orientation from layer to layer is inhibited. The process is reversible upon removal of the drugs. Lumicolchicine has no effect upon microfibril orientation, but granule bands are disorganized. Treatment with coumarin, a known inhibitor of cellulose synthesis, causes the loss of visualization of subunits of the terminal complexes. The possibility of the existence of a membrane-associated colchicine-sensitive orientation protein for cellulose microfibrils is discussed. Transmembrane modulation of microfibril synthesis and orientation is presented.

PMID: 114359 [PubMed - indexed for MEDLINE]

Microalgae and wastewater treatment.

Hammouda O, Gaber A, Abdel-Raouf N.

Botany Department, Faculty of Science, Cairo University, Beni-Suef Branch, Egypt.

The performance of microalgae aquaculture wastewater treatment system predominated mainly by Scenedesmus and Chlorella was assessed. Treatment induced a progressive reduction in both COD and BOD to values below the discharge limits. Different patterns were obtained for removal of phosphorus, nitrogen, and ammonia; however, the algal culture efficiencies reached 100% in their removal by the end of the treatment period. The applied aquatic systems demonstrated percentage reduction of heavy metals in the range between 52.3 and 100% in the batch system and 64.2 and 100% in the continuous system. Wastewater supported algal growth by inducing the incorporation of a significantly higher content of the individual amino acids Asp, Thr, Ser, Glu, Gly, and Tyr, and a markedly higher level of Pro. However, His, Lys, and Arg were markedly reduced compared to their levels in synthetic-medium-grown algae.

PMID: 7498057 [PubMed - indexed for MEDLINE]

Sludge-Grown Algae for Culturing Aquatic Organisms: Part I. Algal Growth in Sludge Extracts

Hung KM, Chiu ST, Wong MH.

Department of Biology & Centre for Waste Recycling and Environmental Biotechnology, Hong Kong Baptist University, Kowloon Tong, Hong Kong

This project is aimed at studying the feasibility of using sewage sludge to prepare culture media for microalgae (Chlorella-HKBU) and the use of the sludge-grown algae as a feed for some aquatic organisms. Part I of the project included results on preparing sludge extracts and their use on algal culture. By comparing two culturing techniques, "aeration" and "shaking," it was noted that both lag and log phases were shortened in the aeration system. A subsequent experiment noted that algal growth subject to aeration rates of 1.0 and 1.5 liters/min had similar lag and log phases. In addition, both aeration rates had a significantly higher (P<0.05) final cell density than that of 0.5 liters/min. A detailed study on the variation of growth conditions on the algal growth was done. The results indicated that pH values of all the cultures declined below 5 at day 12. The removal rates of ammonia N ranged from 62% to 70%. The sludge-grown algae contained a rather substantial amount of heavy metals (&mgr;g/g): Zn 289-581, Cu 443-682, Ni 310-963, Mn 96-126, Cr 25-118, and Fe 438-653. This implied that the rather high levels of heavy metals may impose adverse effects on higher trophic organisms.

PMID: 8661607 [PubMed - as supplied by publisher]

Repeated use of two Chlorella species, C. vulgaris and WW1 for cyclic nickel biosorption.

Tam NF, Wong JP, Wong YS.

Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong. [email protected]

Two living Chlorella species were used to remove nickel from solution containing 30 micrograms Ni ml-1 in 10 successive cycles. The present study also examined the continued viability of these two algal species after repeated exposure to nickel. The two species of Chlorella were Chlorella vulgaris (commercially available) and WW1 (indigenous species isolated from domestic sewage and was tentatively identified as Chlorella miniata). The nickel removal percentage of WW1 cells was maintained at around 85% in the first five cycles, then declined slightly from the fifth cycle onwards, and finally achieved around 70% removal at the end of the 10th cycle. On the contrary, the removal efficiency of C. vulgaris declined from 50 to 30% during the 10 cycles of nickel bisorption. At the end of these 10 successive cycles, WW1 accumulated a substantial amount of Ni2+ (the cumulative cellular Ni concentration was 0.92% dry w.), while the value was only 0.17% in the case of C. vulgaris. These results suggest that the local isolate, WW1, had more consistent and satisfactory ability for removing Ni than the commercial C. vulgaris. Both algal species were still capable of dividing after each nickel treatment cycle, suggesting that the cells were not killed even when significant amounts of nickel were adsorbed/absorbed. However, Ni exposure adversely affected the physiological activity of algal cells as reflected by the decline in division rate and chlorophyll-a activity in both species. Such negative effects became more obvious as the number of cyclic treatments was increased. Nevertheless, WW1 cells appeared to recover from nickel treatment when re-cultivated in commercial medium for 2 weeks.

PMID: 11444009 [PubMed - indexed for MEDLINE]

Cadmium(II) removal from aqueous solutions by pre-treated biomass of marine alga Padina sp.

Kaewsarn P, Yu Q.

School of Environmental Engineering, Nathan Campus, Griffith University, Queensland, 4111 Australia.

In this study, the adsorption properties of a pre-treated biomass from marine alga Padina sp., a biomass collected from Surin Island, Thailand, for removal of cadmium(II) ions from aqueous solutions was investigated. Batch and column experiments were conducted to determine the adsorption properties of the modified biomass. At a pH of 5, the maximum removal capacity of the biomass is 0.53 mmol/g. The kinetics of cadmium(II) adsorption were fast with 90% of adsorption taking place within 35 min. This study demonstrated that the pre-treated biomass of Padina sp. could be used as an efficient biosorbent for the treatment of cadmium(II)-bearing wastewater streams.

PMID: 11234537 [PubMed - indexed for MEDLINE]

Study of the mechanisms of cadmium biosorption by dealginated seaweed waste.

Romero-Gonzalez ME, Williams CJ, Gardiner PH.

Division of Chemistry, School of Science and Mathematics, Sheffield Hallam University, Howard Street, Sheffield S1 1WB, U.K.

The ability of dealginated seaweed waste, a waste material derived from the commercial processing of seaweed for alginate production, to remove cadmium from solution was determined. Cadmium sorption was found to be rapid (91% removal within 5 min), achieving a residual concentration of 0.8 mg L-1 after 1-h contact time from an initial solution concentration of 10 mg L-1. The binding of cadmium by dealginate was found to be pH dependent, optimal sorption occurring at around pH 6-8. The mechanism of cadmium ion binding by dealginate was investigated by a number of techniques. Potentiometric titration of the dealginate revealed two distinct pKa values, the first having a value similar to carboxyl groups and the second comparable with that of saturated thiols and amines. Esterification of the dealginate resulted in the subsequent reduction in cadmium sorption (95% to 17%), indicating that carboxyl groups are largely responsible for sorption. Evidence from FT-IR spectra confirmed the presence of carboxyl groups in untreated dealginate, while the number of carboxyl groups was markedly reduced in the esterified sample. Furthermore, the FT-IR spectrum for dealginate was found to be similar to that previously reported for mannuronic acid-rich calcium alginate. Determination of a molar ratio in the displacement of calcium by cadmium on dealginate further supported the presence of an ion-exchange relationship. The ion-exchange constant was calculated to be 0.329 x 10(-6). The speciation of cadmium in solution both before and after sorption was determined by an ion-selective electrode (ISE) technique. The findings of this study suggest that the sorption of cadmium by dealginate is mainly due to an ion-exchange mechanism.

PMID: 11478258 [PubMed - indexed for MEDLINE]

Homogenous and heterogenous advanced oxidation of two commercial reactive dyes.

Balcioglu IA, Arslan I, Sacan MT.

Bogazici University Institute of Environmental Sciences, Istanbul, Turkey.

Two commercial reactive dyes, the azo dye Reactive Black 5 and the copper phythalocyanine dye Reactive Blue 21, have been treated at a concentration of 75 mg l(-1) by titanium dioxide mediated photocatalytic (TiO2/UV), dark and UV-light assisted Fenton (Fe2+/H2O2) and Fenton-like (Fe3+/H2O2) processes in acidic medium. For the treatment of Reactive Black 5, all investigated advanced oxidation processes were quite effective in terms of colour, COD as well as TOC removal. Moreover, the relative growth inhibition of the azo dye towards the marine algae Dunaliella tertiolecta that was initially 70%, did not exhibit an increase during the studied advanced oxidation reactions and complete detoxification at the end of the treatment period could be achieved for all investigated treatment processes. However, for Reactive Blue 21, abatement in COD and UV-VIS absorbance values was mainly due to the adsorption of the dye on the photocatalyst surface and/or the coagulative effect of Fe3+/Fe2+ ions. Although only a limited fraction of the copper phythalocyanine dye underwent oxidative degradation, 47% of the total copper in the dye was already released after 1 h photocatalytic treatment.

PMID: 11506205 [PubMed - indexed for MEDLINE]

Biosorption and desorption of cadmium(II) by biomass of Laminaria japonica.

Yin P, Yu Q, Lin Z, Kaewsarn P.

Department of Chemistry, Jinan University, Guangzhou 51063, P.R. China.

Biosorption and desorption properties of cadmium(II) from aqueous solutions by the biomass of marine alga Laminaria japonica were investigated. Results indicated that the uptake capacities were solution pH dependent and a maximum uptake capacity of about 1.3 mmol g-1 (dry weight) was observed at pH 6. The adsorbed cadmium cannot be desorbed by distilled water, but it can be effectively recovered by using acidic or EDTA solutions. The equilibrium isotherms can be described well with the Langmuir adsorption equation. Biomass, pre-treated with calcium solution exhibited a higher (about 30%) uptake capacity and can be easily settled from aqueous solutions. Batch kinetics experiments indicated that more than 90% of the adsorption occurred within 20 minutes of agitation and equilibrium was reached within one hour. Fixed-bed experiments showed similar uptake capacities to those of batch results and sharp breakthrough curves were obtained. This study indicated that the biomass of L. japonica can be used as an efficient biosorbent for the removal and recovery of cadmium(II) from waste water streams.

PMID: 11424727 [PubMed - indexed for MEDLINE]

[The efficiency of algae removal from drinking water by ferrate]

[Article in Chinese]

Yuan B, Qu J, Zhang J, Ge X, Liang M, Tian B.

State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China. [email protected]

This paper studied the efficiency of algae removal by ferrate from two kinds of raw water which were collected from Donghu and Tiegang reservoir respectively. The experimental results showed that the removal efficiency of algae reached about 95% only through PAC coagulation when the raw water was extracted from Donghu reservoir in which most of algae was Chlorella. But dealing with Tiegang raw water in which the majority of algae were Oscillatoria, terrate was used as pre-oxidant coupling with PAC coagulation not only using PAC to flocculate and the efficiency of algae removal could be up to 97.85%. However this treatment method using ferrate as pre-oxidant overmatched the traditional method prechlorination for algae removal.

PMID: 11432074 [PubMed - indexed for MEDLINE]

Domoic acid-induced neurodegeneration resulting in memory loss is mediated by Ca2+ overload and inhibition of Ca2+ + calmodulin-stimulated adenylate cyclase in rat brain (review).

Nijjar MS, Nijjar SS.

Department of Anatomy and Physiology, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown C1A 4P3, PEI, Canada. [email protected]

Domoic acid is a shellfish toxin which produces neurodegeneration and CNS dysfunction, notably a loss of short-term memory. This toxin was found in blue mussels (Mytilus edulis) cultivated in river water in the east coast of Prince Edward Island in Canada and caused human poisoning. The toxin was localized in the stomach of blue mussels, which was engorged with algae, Nitzschia pungens, that were filtered from the surrounding water. The toxin was isolated from contaminated mussels or phytoplankton, and identified chemically as domoic acid (DOM) which is a tricarboxylic amino acid. Due to its structural resemblance to glutamic, aspartic and kainic acids, DOM was considered to produce excitotoxicity by similar mechanism(s). However, the latest evidence indicates differences in its mode of action from these excitatory agonists. We propose that DOM induces toxicity via changes in intracellular concentration of Ca2+ ([Ca2+]i). Results of our studies demonstrate that DOM elevated [Ca2+]i in brain slices. Glucose deprivation and removal of Na+ from the Krebs-bicarbonate medium further elevated [Ca2+]i, suggesting a relationship between glucose metabolism (cell energy), Na+ and Ca2+ transfer across neuronal membrane. DOM-induced rise in [Ca2+]i was due to enhanced Ca2+ influx and its mobilization from the endoplasmic reticulum. In addition, diminished Ca2+-ATPase activity due to lack of ATP, and variable amounts and expression of calcium binding proteins (CaBP) appear to contribute to an elevation in [Ca2+]i in response to DOM. Most interestingly, DOM inhibited Ca2+ and calmodulin-stimulated adenylate cyclase activity in brain membranes, resulting in reduced level of cyclic AMP. Cyclic AMP is known to activate protein kinase A to enhance phosphorylation of Ca2+ channels, thereby, reducing Ca2+ influx to prevent the development of Ca2+ overload which is detrimental to neuronal cell function (neuroprotection). However, DOM reduced cyclic AMP level, diminishing the feedback control of cyclic AMP on Ca2+ influx via Ca2+ channels, thereby, allowing continuing enhanced Ca2+ influx, resulting in Ca2+ overload which adversely affects many intracellular processes to induce toxicity. Ca2+ and CaM-stimulated adenylate cyclase activity in brain is highly correlated with the acquisition and retention of memory in different organisms. Calcium binding proteins bind Ca2+ reversibly and provide intracellular Ca2+ buffering, thereby, protecting neuronal cell from damage by Ca2+ overload in response to DOM. DOM appears to interfere with the cross talk between Ca2+ and cyclic AMP which is necessary for neuronal cell function. We have also demonstrated that DOM stimulates GLU release from synaptosomes and may produce some of its toxic effects via excess GLU in the neuronal synapse. In conclusion, DOM-induced neurodegeneration resulting in a loss of memory is mediated by Ca2+ overload, inhibition of Ca2+ and CaM-stimulated adenylate cyclase activity, and/or by the enhanced GLU release in rat brain.

Publication Types:

Review

Review, Tutorial

PMID: 10998428 [PubMed - indexed for MEDLINE]

Extraction of mercury from groundwater using immobilized algae.

Barkley NP.

U.S. Environmental Protection Agency, Risk Reduction Engineering Laboratory, Cincinnati, Ohio.

Bio-Recovery Systems, Inc. conducted a project under the Emerging Technology portion of the United States Environmental Protection Agency's (EPAs) Superfund Innovative Technology Evaluation (SITE) Program to evaluate the ability of immobilized algae to adsorb mercury from contaminated groundwater in laboratory studies and pilot-scale field tests. Algal biomass was incorporated in a permeable polymeric matrix. The product, AlgaSORB, packed into adsorption columns, exhibited excellent flow characteristics, and functioned as a "biological" ion exchange resin. A sequence of eleven laboratory tests demonstrated the ability of this product to adsorb mercury from groundwater that contained high levels of total dissolved solids and hard water components. However, use of a single AlgaSORB preparation yielded nonrepeatable results with samples collected at different times of the year. The strategy of sequentially extracting the groundwater through two columns containing different preparations of AlgaSORB was developed and proved successful in laboratory and pilot-scale field tests. Field test results indicate that AlgaSORB could be economically competitive with ion exchange resins for removal of mercury, with the advantage that hardness and other dissolved solids do not appear to compete with heavy metals for binding capacity.

PMID: 1777231 [PubMed - indexed for MEDLINE]

Cell wall lytic enzyme released by mating gametes of Chlamydomonas reinhardtii is a metalloprotease and digests the sodium perchlorate-insoluble component of cell wall.

Matsuda Y, Saito T, Yamaguchi T, Kawase H.

Chlamydomonas lytic enzyme of the cell wall, which is released during agglutination of gametes of opposite mating types, has been characterized as a metalloprotease. The purified enzyme contains zinc. Removal of zinc with EDTA results in an inactive, metal-free apoenzyme, and Co2+ restores the activity most effectively. Among various protease inhibitors of microbial origin, pepstatin A, chymostatin, antipain, leupeptin, and E-64 do not inactivate the enzyme, whereas phosphoramidon causes a complete loss of lytic activity. Cysteine, histidine, aspartic acid, and glutamic acid also inhibit the activity. The lytic enzyme splits casein and RNase A into several polypeptides of lower molecular masses. To determine which polypeptides of the cell wall are sensitive to the lytic enzyme, we first separated the intact cell walls into sodium perchlorate-soluble and -insoluble components, treated them with enzyme, and then analyzed them by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and silver staining. We conclude that only 2 of 16 polypeptides are digested by exposure to the enzyme and that the sensitive polypeptides belong to the salt-insoluble component of the cell wall. The mechanism of cell wall digestion with the lytic enzyme is discussed.

PMID: 3888980 [PubMed - indexed for MEDLINE]

Screening of marine microalgae for bioremediation of cadmium-polluted seawater.

Matsunaga T, Takeyama H, Nakao T, Yamazawa A.

Department of Biotechnology, Tokyo University of Agriculture and Technology, Japan. [email protected]

Twenty four strains out of 191 marine microalgal strains exhibited cadmium (Cd) resistance. They were tested for their Cd removal ability in growth media containing 50 microM Cd. Six strains out of 19 green algae and one out of five cyanobacteria removed more than 10% of total Cd from the medium. The marine green alga Chlorella sp. NKG16014 showed the highest removal of Cd 48.7% of total. Cd removal by NKG16014 was further quantitatively evaluated by measuring the amount of cell adsorption and intracellular accumulation. After 12 days incubation, 67% of the removed Cd was accumulated intracellularly and 25% of the Cd removed was adsorbed on the algal cell surface. The maximum Cd adsorption (qmax) was estimated to be 37.0 mg Cd (g dry cells)-1 using the Langmuir sorption model. The Cd removal by freeze-dried NKG16014 cells was also determined. Cd was more quickly adsorbed by dried cells than that by living cells, with a qmax of 91.0 mg Cd (g dry cells)-1.

PMID: 10412204 [PubMed - indexed for MEDLINE]

Disassembly and reconstitution of a membrane-microtubule complex.

Murray JM.

The cell membrane of the unicellular algae Distigma proteus is associated with arrays of parallel microtubules. Fragments of the membrane-microtubule complex have been isolated and partially purified. The microtubules were stable in vitro at room temperature as well as at 0 degree C, but were specifically and rapidly disassembled by Ca2+. After removal of all endogenous microtubules, the membrane-microtubule complex could be reassembled from brain microtubule protein and denuded Distigma membrane fragments. The readded microtubules bound in a fixed orientation, and only to those regions of membrane that are normally associated with microtubules in vivo.

PMID: 6715410 [PubMed - indexed for MEDLINE]

Regulation of metallothionein synthesis in HeLa cells by heavy metals and glucocorticoids.

Karin M, Slater EP, Herschman HR.

Metallothioneins (MTs) are low molecular weight, cysteine-rich proteins that bind heavy metals. MT induction occurs in liver in response to either heavy metal (Zn++ or Cd++) administration or stress. The synthesis of MT can also be induced by either heavy metals or glucocorticoid hormones in HeLa cells cultured in serum-free medium. Induction of MT by zinc is subject to "desensitization." In contrast, dexamethasone (dex) induction results in a continued elevation in the rate of MT synthesis. The stability of MT is dependent on the availability of metal; consequently, MT induced by dex is degraded much more rapidly (half-life of 11 to 12 hours) than MT induced by elevated zinc levels (half-life of 36 to 38 hours). Removal of either inducer results in biphasic degradation curves, as apothionein and zinc come into balance. In contrast, deinduction kinetics for MT synthesis following removal of the two inducers (zinc and dex) are the same, with a half-life of two and one-half hours. Inhibition of RNA synthesis blocks deinduction after removal of inducer. Induction of MT occurs in a wide variety of species, from blue-green algae to man. This system should provide an excellent model for the comparative biochemistry of regulation of gene expression.

PMID: 6162854 [PubMed - indexed for MEDLINE]

Removal and distribution of iron, manganese, cobalt, and nickel within a Pennsylvania constructed wetland treating coal combustion by-product leachate.

Ye ZH, Whiting SN, Lin ZQ, Lytle CM, Qian JH, Terry N.

Department of Plant and Microbial Biology, Univ of California at Berkeley, 94720, USA.

A flow-through wetland treatment system was constructed to treat coal combustion by-product leachate from an electrical power station at Springdale, Pennsylvania. In a nine-compartment treatment system, four cattail (Typha latifolia L.) wetland cells (designated Cells 1 through 4) successfully removed iron (Fe) and manganese (Mn) from the inlet water; Fe and Mn concentrations were decreased by an average of 91% in the first year (May 1996-May 1997), and by 94 and 98% in the second year (July 1997-June 1998), respectively. Cobalt (Co) and nickel (Ni) were decreased by an average of 39 and 47% in the first year, and 98 and 63% in the second year, respectively. Most of the metal removed by the wetland cells was accumulated in sediments, which constituted the largest sink. Except for Fe, metal concentrations in the sediments tended to be greater in the top 5 cm of sediment than in the 5- to 10- or 10- to 15-cm layers, and in Cell 1 than in Cells 2, 3, and 4. Plants constituted a much smaller sink for metals; only 0.91, 4.18, 0.19, and 0.38% of the Fe, Mn, Co, and Ni were accumulated annually in the aboveground tissues of cattail, respectively. A greater proportion of each metal (except Mn) was accumulated in cattail fallen litter and submerged Chara (a macroalga) tissues, that is, 2.81, 2.75, and 1.05% for Fe, Co, and Ni, respectively. Considerably higher concentrations of metals were associated with cattail roots than shoots, although Mn was a notable exception.

PMID: 11476526 [PubMed - indexed for MEDLINE]

Calcium effects on electrogenic pump and passive permeability of the plasma membrane of Chara corallina.

Bisson MA.

Removal of Ca2+ from the medium results in depolarization of the Chara internodal cell and an increase in membrane conductance (Gm). The increase in conductance is associated with an increase in K+ conductance, as judged by Ca2+ effects on the K+ dependence of clamp current. The voltage dependence of Gm is also affected by Ca2+, as is the time course of the response of clamp current to a step change in voltage. Mg2+ restores the low conductance and the fast response to a voltage change, but not hyperpolarization at neutral pH, suggesting that there is an additional, independent effect on the electrogenic pump. The membrane does not show the normal ability to increase proton conductance at high pH in the absence of Ca2+; this is also restored by Mg2+ as well as by Ca2+.

PMID: 6492130 [PubMed - indexed for MEDLINE]

Algae removal using dissolved air flotation.

Bare WF, Jones NB, Middlebrooks EJ.

PMID: 1121045 [PubMed - indexed for MEDLINE]

Manganese oxidation in pH and O2 microenvironments produced by phytoplankton.

Richardson LL, Aguilar C, Nealson KH.

Center for Great Lakes Studies, University of Wisconsin, Milwaukee 53204, USA.

Pure cultures of Chlorella sp. catalyzed the oxidation of soluble Mn(II) to particulate, extracellular, manganic oxides. Manganese oxidation was dependent on photosynthetic activity: no oxidation was observed in the dark when cells were grown heterotrophically on glucose, or in the light when photosystem II was inhibited by the addition of DCMU. Manganates were not formed when media were buffered below pH 8.0, suggesting that an important driving force for manganese oxidation was the high pH resulting from photosynthesis. Field studies with minielectrodes in Oneida Lake, New York, demonstrated steep gradients of O2 and pH and the presence of particulate manganic oxides associated with pelagic aggregates of the cyanobacterium Microcystis sp. The manganese oxidation reaction apparently occurs only when photosynthesizing algae are present as dense populations that can generate microenvironments of high (>9.0) pH, either as aggregates in the pelagic zone or concentrated cell cultures in the laboratory. A large-scale transition from soluble to particulate manganese was measured in the surface waters of Oneida Lake throughout summer 1986. Removal of Mn(II) was correlated with the presence of aggregate-forming cyanobacteria that oxidize Mn(II) by the mechanism described above.

PMID: 11538363 [PubMed - indexed for MEDLINE]

Energy dependence and reversibility of membrane alterations induced by polyene macrolide antibiotics in Chlorella vulgaris.

Malewicz B, Borowski E.

The requirement of metabolic energy for the interaction of polyene macrolide antibiotics with eukaryotic organisms remains a controversial subject (for review see ref. 1) It has been claimed that the lethal binding of these antibiotics to the sterol target component of the hydrophobic core of the membrane, in accordance with the model of de Kruijff and Demel, is an energy-dependent process. When energy production is reduced by removal of all metabolisable substrates or by adding metabolic inhibitors, polyene binding and antifungal effects are also reduced. Metabolic energy may be required to maintain binding site accessibility or to move antibiotic molecules to the active site. The interaction is also restricted at low temperatures, possibly because of the reduced thermal mobilities of the groups concerned with antibiotic uptake. However, it should be emphasised that the interaction of polyene macrolides with artificial lipid membranes is a purely physicochemical process, although the type of permeability pathways induced are similar to those observed in natural membranes. Using Chlorella vulgaris as a model organism, we demonstrate here that the interaction of polyene macrolides with sensitive cells and the induction of lethal membrane permeability changes are energy-dependent processes or purely physicochemical phenomena, depending on the structure of the antibiotic used.

PMID: 551270 [PubMed - indexed for MEDLINE]

Movement of scallop myosin on Nitella actin filaments: regulation by calcium.

Vale RD, Szent-Gyorgyi AG, Sheetz MP.

In order to determine if Ca2+ regulates scallop myosin movement on actin, we have measured motility of scallop myosin along actin filaments using a direct visual assay. This procedure consists of covalently linking myosin to 1-micron beads and pipetting them onto a parallel array of actin filaments located on the cytoplasmic face of a Nitella internodal cell. In the absence of Ca2+, scallop myosin-coated beads exhibit no directed motion; however, in the presence of pCa2+ of greater than 5.84, these beads undergo linear translocations with average velocities of 2.0 micron/s. This Ca2+ -sensitive motility requires the presence of regulatory light chains on the scallop myosin. Removal of regulatory light chains with 10 mM EDTA produces a "desensitized" myosin, no longer sensitive to Ca2+, which moves at rates of 0.09-0.3 micron in the presence or absence of Ca2+. Readdition of regulatory light chains to preparations of desensitized myosin once again confers Ca2+-sensitive motility. The Ca2+ dependence of scallop-myosin motility shows a sharp transition, consistent with the Ca2+ activation sensitivity of the actin-activated ATPase. Furthermore, relative rates of movement of calcium-regulated myosins from various molluscan species are consistent with their respective rates of ATP hydrolysis. Thus, myosin motility along actin filaments provides a sensitive and direct assay of myosin activity and is suitable for studying myosin regulation.

PMID: 6238334 [PubMed - indexed for MEDLINE]

Nutrient profiles in the everglades: examination along the eutrophication gradient.

Vaithiyanathan P, Richardson CJ.

Duke University Wetland Center, Loxahatchee, FL 33470, USA.

We examined the concentration profiles of nutrients in the surface water, soil and pore water along the eutrophication gradient of the Water Conservation Area-2A (WCA-2A) in the northern Everglades. Phosphorus levels in the surface waters contributed by the agricultural runoff showed an exponential decrease downstream of the inflow structures attaining background values of 7-12, 7-9 and 5-6 micrograms l-1 of TP, TDP and PO4-P, respectively, at distances of 8-10 km. The pore water PO4-P concentration in the oligotrophic areas ranged between 5 and 10 micrograms l-1. Molar ratios of dissolved inorganic N and P suggest a possible switch in nutrient limitation in the surface water from P in the oligotrophic areas to N in the eutrophic areas (DIN:DIP approximately 5). External nutrient loading has also contributed to a three- to four-fold increase in soil TP concentration and enhanced pore water PO4-P in the northern marshes. Unlike P, C and N concentration in the soils remained fairly uniform along the eutrophication gradient. 210Pb dating of soil cores suggests that the increase in soil P concentration (from < 500 to 1500 micrograms g-1) and P accumulation rate (from 0.06 to 0.46 g P m-2 per year) at the eutrophic site correlates with the installation of inflow structures in 1960-1963 through which agricultural drainage from the Hillsboro canal enters the marshes. Organic P makes up 70-90% of the total P in the soils as uptake by algae and macrophytes is the primary mechanism of P removal in these wetlands. Calcium supply from the underlying bedrock suggested from the surface and pore water chemical profiles has important consequences for P-cycling in the Everglades as Ca-bound P is the major form of inorganic P storage in the soils.

PMID: 9352671 [PubMed - indexed for MEDLINE]

Photocatalytic degradation of cyanobacterial microcystin toxins in water.

Shephard GS, Stockenstrom S, De Villiers D, Engelbrecht WJ, Sydenham EW, Wessels GF.

Programme on Mycotoxins and Experimental Carcinogenesis, Medical Research Council, Tygerberg, South Africa.

The microcystins are hepatotoxins produced by a number of cyanobacterial species (blue green algae) in fresh water systems. The increasing eutrophication of natural waters has led to an increase in the incidence of algal blooms and the consequent increased risk of microcystin contamination of water resources. The removal of microcystins LR, YR and YA from contaminated water was investigated using an experimental laboratory-scale photocatalytic 'falling film' reactor in which an oxygen purge, UV radiation and semiconductor titanium dioxide (TiO2) catalyst were used to oxidatively decompose the microcystin pollutants. Preliminary studies, using algal extracts spiked into distilled water, indicated that the microcystins were rapidly decomposed in this reactor. The decomposition followed first order reaction kinetics with half-lives of less than 5 min with the reactor operating in a closed-loop mode. Reaction rates were strongly dependent on the amount of TiO2 catalyst (O-5 g/l), but only marginally influenced by a change in gas purge from oxygen to compressed air. The use of lake water, rather than distilled water, showed that this process is feasible in natural waters, although increased levels of catalyst (up to 5 g/l) were required to achieve comparable decomposition rates.

PMID: 9839673 [PubMed - indexed for MEDLINE]

Biosorption of chromium(VI) from aqueous solutions by green algae Spirogyra species.

Gupta VK, Shrivastava AK, Jain N.

Department of Chemistry, University of Roorkee, India. [email protected]

Biosorption of heavy metals is an effective technology for the treatment of industrial wastewaters. Results are presented showing the sorption of Cr(VI) from solutions by biomass of filamentous algae Spirogyra species. Batch experiments were conducted to determine the adsorption properties of the biomass and it was observed that the adsorption capacity of the biomass strongly depends on equilibrium pH. Equilibrium isotherms were also obtained and maximum removal of Cr(VI) was around 14.7 x 10(3) mg metal, kg of dry weight biomass at a pH of 2.0 in 120 min with 5 mg/l of initial concentration. The results indicated that the biomass of Spirogyra species is suitable for the development of efficient biosorbent for the removal and recovery of Cr(VI) from wastewater.

PMID: 11791837 [PubMed - in process]

A new method for extraction of extracellular polymeric substances from biofilms and activated sludge suitable for direct quantification of sorbed metals.

Wuertz S, Spaeth R, Hinderberger A, Griebe T, Flemming HC, Wilderer PA.

Institute of Water Quality Control and Waste Management, Technical University of Munich, Am Coulombwall, D-85748 Garching, Germany. [email protected]

A method for extraction of extracellular polymeric substances (EPSs) with a dicyclohexyl-18-crown-6 ether was developed to determine levels of organic and inorganic contaminants sorbed to EPS. The crown ether selectively binds alkaline and alkaline earth metals but not heavy metals. The effectiveness of the extraction procedure was higher than that of 2 other methods tested and comparable with that of a method based on a cation exchange resin. On average it was possible to extract 20% of the TOC, 12% of the total protein content, and 4% of the total carbohydrate content of sludge or biofilm biomass. Metal sorption studies in activated sludge showed no influence of exposure time on the fractionation of metals within the biomass. Metals sorbed mostly to cellular material. In biofilms 12.2% of the cadmium and 9.1% of the zinc added was found in the EPS. In activated sludge EPS contained only 2.9% zinc. The distribution of metals within the biomass was dose dependent. The percentage of metals found in EPS decreased with increasing metal concentration. This indicates a higher affinity of metals for cellular binding sites. Time course experiments in a rotating biofilm annular reactor, which consisted of an external cylinder with removable slides and an internal solid drum, revealed a gradual change in zinc concentration associated with EPS, although the total zinc concentration in the biomass remained constant. Concurrently, the amount of extractable EPS decreased. This was a consequence of a microbial population shift, with bacterial counts decreasing and algal and fungal biomass increasing. Using confocal laser scanning microscopy and the fluorescent metal complexing agent Newport Green for in situ detection of zinc it was shown that metals were bound to algae and fungi in the latter part of the experiment. The biofilm became more and more heterogeneous coinciding with a decrease in EPS. To summarize, the observed sorption behavior of metals cannot be explained with the conventional paradigm of EPS as hydrophilic gel. Obviously, different binding mechanisms must be invoked to explain the role of EPS in the sorption and removal of toxic substances in activated sludge and biofilm systems. It is important to consider the microbial population to understand differences in sorption in different matrices.

PMID: 11381969 [PubMed - indexed for MEDLINE]

Calcium influx, fertilisation potential and egg activation in Fucus serratus.

Roberts S, Brownlee C.

Marine Biological Association, Plymouth, UK.

Fertilisation in the marine alga Fucus serratus is accompanied by increased influx of Ca2+ from the external medium. The onset of this increase, monitored with the Mn2+ fluorescence quench technique, corresponded with the depolarisation phase of the fertilisation potential. External Ca2+ was necessary for the onset of the fertilisation potential and the early activation events, including cell wall exocytosis. Removal of Ca2+ from, or addition of Sr2+ to, the external medium during the fertilisation potential reduced the magnitude of the depolarisation and prolonged its duration. While fertilisation potentials could not be elicited in the presence of 0.1 mM Ca2+, addition of Ba2+ in the presence of 0.1 mM Ca2+ allowed normal fertilisation potential and egg activation. Microinjection of ryanodine or cyclic guanosine 5' -monophosphate (cGMP) did not induce cytoplasmic Ca2+ elevation or egg activation. Inositol 1,4,5-triphosphate [Ins(1,4,5)P3] produced a transient elevation of cytoplasmic Ca2+, monitored using ratio photometry, but did not cause cell wall exocytosis except at the site of microinjection. The results demonstrate an essential role for Ca2+ influx during Fucus egg activation. The relative importance of influx and intracellular Ca2+ release in Fucus egg activation is discussed.

PMID: 8903788 [PubMed - indexed for MEDLINE]

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