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Abstract. Fine bubble aeration diffusers are the most efficient means of transferring oxygen into process water and wastewater. A fine pore disc diffuser is developed with membrane of special HD-PE material and provides excellent chemical and thermal properties for the most challenging environments.

The HD-PE diffuser element is with open pores throughout the solid plate and creates micro-bubbles, that results in increased oxygen transfer efficiency.

Effects of a biosurfactant-rhamnolipid on bacterial growth and protein release

A. Sotirova, D. Galabova, E. Vasileva-Tonkova, E. Karpenko, A. Shulga

Abstract. The biosurfactant-rhamnolipid PS from Pseudomonas sp. S-17 contains a unique natural complex of a biosurfactant and a biopolymer-alginate with high surface and emulsifying activities. The biosurfactant is a mixture of two homologous extracellular glycolipids.Effects of a novel biosurfactant-rhamnolipid PS in batch cultures of Ps. aeruginosa, E. coli and B. subtilis on the growth, extracellular protein levels and cell permeabilization were studied. The biosurfactant was shown to have a neutral or detrimental effect on the growth of Gram (+) strains and it was dependent on the surfactant concentration. The biosurfactant PS produced effects well expressed in vivo as well as in vitro on the B. subtilis 168 culture. The growth of Gram (-) strains was not influenced by the presence of biosurfactant in the media.

Peculiarities of the research organization in bioprocess engineering. Part 1. Objects of investigation and specificity of experimental work

L. Nikolov

Abstract. Peculiarities of the research organization in the field of Bioprocess Engineering are revealed. In the Part 1. it is made on the basis of comparative analysis of the objects of R&D activity and experiments in Bioprocess Engineering with those of other sciences, such as Chemistry, Biology and Chemical Engineering. The next parts of this study treat the implementation of the Program-Target Method and the System Approach to the organization activity, emphasizing on its specificity of each of the stages in the research development. Some considerations about the improvement of R&D activity organization in the field of Bioprocess Engineering are made.

Modelling of food waste anaerobic digestion in one-stage digester under waste and microorganisms spatially separated

V. Vavilin, L. Lokshina

Abstract. A distributed mathematical model of anaerobic digestion of rich (food) and lean (non-food) solid wastes with definitely different rates of polymer hydrolysis/acidogenesis was developed to describe the balance between the rates of hydrolysis/acidogenesis and methanogenesis. The model was calibrated using previously published experimental data (Cho et al. 1995) where various initial food waste (FW) loadings were used. Simulations of one- and two-stage digestion systems were carried out. It was shown that an initial spatial separation of FW and inoculum enhanced methane production and waste degradation in one-stage solid-bed digester at high waste loading.

A hybrid biosensor with biochemical amplification

V. Rangelova, St. Gospodinov, A. Pandelova

Abstract: A hybrid biosensor for catechol concentration measurement is investigated. There is a cyclic reaction for the substrate which increases biosensor's sensitivity. A tissue from potato plant and mushroom is used as an active membrane and L-ascorbic acid is a non-measurable substrate. An oxygen electrode is a based transducer. For hybrid biosensors with cyclic enzyme-chemical reaction, experimental transfer functions are obtained and coefficient of amplification is calculated.

Activities on the genetic preservation of conifer species in Bulgaria

A. Alexandrov, D. Pandeva

Abstract: The conifer forests in Bulgaria cover about 1/3 of the afforested area and they are composed of 12 indigenous species: 5 of genus Pinus, 4 of genus Juniperus and by one of the genera Picea, Abies and Taxus. They are distributed mainly in the mountainous regions, which determines their great anti-erosion and water-protection role. The area of the seed stands from indigenous conifer species as percentage of the area of the conifer forests is 2% but in the last decades the afforestation with conifer species shows tendency to decrease.

Spatial modelling of the health status of the Chouprene biosphere reserve forests

E. Roumenina, V. Dimitrov

Abstract: The paper deals with the problem of influence of relief characterisitics on health status of old-growth spruce and beech forest formations in Chouprene biosphere reserve. A modeling procedure is developed based on 3D and spatial analysis in a geographic information system. During the modeling new thematic layers are generated and thematic maps are composed. Quantitative results are obtained about the presence of a relation between the health status of spruce and beech formations and relief characteristics.

Plant biotechnologies in the XXI century – a rescue of mankind

G. Kosturkova

Abstract: The Global population is estimated to reach 8 billion people by 2020 creating a problem in meeting the demands of food. Increasing of food production on the basis of expanding the cultivated agricultural areas is limited. Hence, increasing productivity on the basis of new technologies is a possible solution. Biotechnologies have developed rapidly passing from the sphere of science into the sphere of industry. However, some moral and legal issues have arisen. All this problems are discussed in the paper.

EEEP 3/2003

CONTENTS

Managing editor's comment

I. Simeonov 3

I. Human and Biosphere

L. Nikolov 25

A hybrid biosensor with biochemical amplification

Activities on the genetic preservation of conifer species in Bulgaria

Plant biotechnologies in the XXI century – a rescue of mankind

A hybrid biosensor with biochemical amplification

Activities on the genetic preservation of conifer species in Bulgaria

Plant biotechnologies in the XXI century – a rescue of mankind