Dr R Rengasamy

Expertise available with the group

          Algal research by Dr. R. Rengasamy and his group initiated since 1977.   The participation in the International workshop on ‘The Production and Utilization of commercial seaweeds’ at the Institute of Quingdao, China organized by FAO, UN in 1987 helped him to understand better about the cultivation of Eucheuma, Laminaria and Porphyra apart form the extraction and estimation of different chemical constituents of agar, carrageenan and alginate.
The PI has successfully demonstrated the life history of brown seaweed, Padina tetrastromatica under laboratory conditions. The tetraspores released from the sporophyte developed into gametophytes and they were approximately 50% female and 50% male gametophytes.  Further he observed seasonality of the development of tetraspores into mature gametophytes.  He has studied the growth, pigments, carbohydrate and protein content of different seaweeds like Gracilaria edulis, G. verrucosa, Hypnea musciformis, H. valentiae, Ulva fasciata, U. reticulata and Entermorpha flexuosa under different laboratory conditions.  He has demonstrated the possibility of growing the seaweed G. verrucosa in the back waters of Muttukadu, near Chennai by adapting cage culture.  Indoor co-cultivation of shrimps like Penaeus mondon and P. indicus with Gracilaria verrucosa and Gracilaria sp. and Ulva reticulata revealed the importance of seaweeds in the nutrient removal especially on the reduction of ammonium nitrogen generated from the excreta of the animals for their biomass productivity.  Outdoor cultivation of Gracilaria verrucsoa and Ulva fasciata in 40% sewage + seawater indicated the significance of seaweeds in BOD, COD, nitrogen and phosphorus reduction apart from the reduction of coli forms.
Further, he demonstrated by growing the seaweed like Enteromorpha flexuosa in the fly ash effluent generated from the Ennore Thermal Power Station, Chennai.  This seaweed was able to grow well in the effluent and removed the heavy metal like Cu up to 85%. Investigations made on the halophyte, Sesuvium portulacastrum exhibited the removal of sodium and chloride from effluent of a multinational beverage company up to 30%.
Apart from the above, the PI has standardized the techniques for the extraction of phycocolloids like agar and carrageenan and their estimation of chemical constituents like galactose, 3, 6 anhydrogalactose and sulphate; and alginate and its chemical constituents like mannuronic and guluronic acids.
An investigation on Environment Impact Assessment on the cultivation region of Kappaphycus alvarezii along the coast of Mandapam, sponsored by Department of Environment, Tamil Nadu was taken up.   He is a frequent visitor to the Mandapam region and familiar with the seaweeds present in the area.  The seaweeds like Sargassum polycystem and S. wightii were taken for the ultrastructure and histochemical studies.  The seaweeds were also collected during different seasons and extracted alginate and analyzed for its chemical composition like D-mannuronic acid (D block), L – guluronic acid (M block) and alternating sequences of D and L blocks (MG Block) as well as determined its viscosity.
The efficacy of Seaweed Liquid Fertilizers (SLFs) obtained from Kappaphycus alvarezii, Sargassum and Ulva for the growth and yield of certain crops like paddy, ground nut, chilly, greens and marigold was made under field trial. The SLFs were also analyzed for macro and micro nutrients as well as Plant Growth Regulators like Auxin, Gibberellin and Cytokinin.  The brown algal by products like ‘Seaweed Organic Manure’ and ‘Organic Six’ derived from Sargassum sp. developed by a seaweed based company at Ranipet, Tamil Nadu is assessed for their nutrients and microbial populations in order to evolve strategy for rapid degradation.  Two compounds successfully isolated from the ‘Seaweed Organic Manure are inhibited the growth of Xanthomonas oryzae pv. oryzae causing leaf blight disease of paddy. 
A halotolerant green alga, Dunaliella is known to accumulate a high amount of beta carotene, which has anti-oxidant and anti-cancer properties. More than 20 isolates of Dunaliella are isolated from the salt pans of Tamil Nadu and Andhra Pradesh coasts and maintained in DeWalne’s medium under laboratory conditions. Two strains of Dunaliella salina are known to contain more than 80mg/L of beta carotene.
In general, the diatoms like Chaetoceros and Skeletonema are widely used as feed in shrimp hatchery. A comparative study made on these diatoms and Dunaliella separately as a feed for the animal Artemia, revealed that the animals fed with Dunaliella contained high nutritional values than others. A preliminary study undertaken for its anti-cancer property of Dunaliella towards Fibrosarcoma in wistar rats showed promising results.     
A marine bacterium, Exiguobacterium aestuari  isolated from a red seaweed Gracilaria corticata known to contain agarase. Suitable physico-chemical conditions are evolved for the maximum production of agarase. Presence of bio-active substances from seaweeds is well documented, however investigations towards plant pathogens are found meager.  Ethyl acetate extract of the brown seaweed, Turbinaria conoides is able to control leaf spot disease caused by Brevindimonas diminuta on a medicinal plant, Phyllanthus amarus cures jaundice. Two active compounds isolated from the seaweed extract are characterized. Thus the significance of seaweed for the development of biocides is confirmed.
Hydrobiological features of Chembarambakkam and Puzhal lakes near Chennai are studied intensively for a period of two years.  The water of the lakes found portable.  Recently, a multinational company sanctioned a project to isolate Botryococcus braunii from South Indian water bodies for biodiesel production. More than 32 isolates of Botryococcus of varying morphological features are isolated and maintained in BBM - medium under the laboratory conditions.  A green fresh water alga Heamatococcus pluvialis isalso grown under the laboratory conditions.  Physicochemical parameters are standardized for high accumulation of Astaxanthin production  of the alga. Further the astaxanthin is evaluated for its antioxidant and anti cancer properties.  Recently an attempt is being made for bio gas production from seaweed and sea grass.
Ph.D. awarded under the guidance of Prof. R. Rengasamy
1. Dr. R. Hemalatha  - Gracilaria edulis, growth, agar constituents
2. Dr. K. Arun kumar – Seaweeds, biocides, Xanthomonas oryzae pv. oryzae
3. Dr. K. Siva kuamr – Hypnea, TEM, kappa carrageenan 
4. Dr. B. Babu – Fucales, TEM
5. Dr. N. Thangaraju – Seaweed Liquid Fertilizer
6. Dr. S. Jothi saraswathi – Fucales, TEM
7. Dr. C. Anbazhagan – Seaweeds, domestic effluent treatment
8. Dr. R. Raja – Dunaliella, anti cancer
9. Dr. S. Sridhar- Seaweed Liquid Fertilizer
10. Dr. Ashok kumar – Hydrobiology, phytoplankton
11. Dr. C. Periasamy – Fresh water bodies, hydrobiology
12. Dr. S. V. Roopchander – Phycoremediation, tannery effluent
13. Dr. C. Sreenath kumar – Seaweeds, biocides, Phyllanthus amaras 
14. Dr. Senthil swamy –  Dunaliella, culture conditions, β Carotene
15. Dr. D. L. V. Sarada – Seaweeds, fly ash effluent treatment
16. Dr. T. Paul Gideon – Sargassum, polysaccharide, anti cancer