UNIVERSITY OF LATVIA INSTITUTE OF MICROBIOLOGY AND BIOTECHNOLOGY

Director Dr.habil.sc.ing. U. VIESTURS, Full mem. LAS
Chair of the Council Dr.habil.biol. M. BEKERS, Full mem. LAS

The Institute was founded in 1993 as the successor and inheritor of rights of the LAS Augusts Kirhensteins Institute of Microbiology. The main research directions, started at the LAS Institute of Microbiology are continued. Besides, great attention is focused on the integration in the State system of higher education. Top experts of the Institute deliver courses of lectures and conduct practical classes for the students of the University of Latvia and the Riga Technical University as well as work with researchers for Master's and Doctor's degrees. The equipment of the scientific laboratories of the Institute is partially brought over to the premises of the University of Latvia Faculty of Biology and adjusted to the specific requirements of the study process there. The Institute is developing co-operation with other research establishments and various companies both in Latvia and abroad. Purpose of co-operation-theoretical research as well as practical elaborations.

Main Areas of Research

• Genetics, physiology, cytology, biochemistry, and bioenergetics of micro-organisms (A. Rapoports, Cor.mem. LAS; P. Zikmanis, U. Kalnenieks, L. Savenkova, and J. Raipulis).

• Biotechnology of microbial biosynthesis and conversion of substances, bioengineering (M. Bekers, Full mem. LAS; M. Ruklisa, M. Rikmanis, I. Vina, and A. Danilevics).

• Microbiological processes and preparations in agriculture and in protection of the environment ( A. Apsite and Dz. Zarina).

Main Results in 1996

• Basically new information has been obtained on ethanol producing bacteria Zymomonas mobilis osmotolerance, components of electron transporting chain and their localization, bioenergetic regulation with cytokinins as well as on biosynthesis regulation of biodegradable polymers in Azotobacter cultures.

• It was shown in cooperation with the Lund University Department of Applied Microbiology (Prof. B. Hahn-Hagerdal) that such polyol as xylitol can function during dehydration procedure as a protective substance not only for the intracellular membranes but for other essential cellular components too (probably, nucleic acids and proteins).

• It was shown in cooperation with the University of California Section of Molecular and Cellular Biology (Prof. John H. Crowe) that special yeast cell pretreatments, which increase the organisms stability to dehydration, diminish the membrane lipid phase transition temperatures in anhydrobiotic cells.

• The resistance of yeast to the Cr(VI) and optimization of the Cr(VI) sorption process by dehydrated yeasts were investigated. In co-operation with the Laboratory of the Bioenergetics of Membranes, Institute of Biochemistry, University of Paris, Orsay (Prof. B. Arrio, Dr. M. Zinovyeva) the changes of the cell surface charge during sorption process were estimated and the sites of metal accumulation within the cell were determined.

• Production of poli-beta-hydroxybutirate (PHB) in strain of Azotobacter chrococcum was investigated at various levels of oxygen and phosphate. An optimum initial phosphate concentration in the cultivation medium has been determined and a possibility of regulating the PHB production process by the phosphate level in the cultivation medium has been demonstrated. 36 hour feed-batch fermentation resulted in the biomass yield 110g/l with the PHB content 79 percent cell dry weight and system productivity 2.29 g/l h.

• The existence of a special growth control mechanism in lysine producing Corynebacteria was established. This mechanism was observed to be due to a decrease in oxygen consumption rate of bacteria and an increase in the cellular guanosine 5'-diphosphate 3'-diphosphate (ppGpp) concentration in conductions when the concentration of auxotrophic amino acids in the medium was not a growth limiting factor, i.e. 'stringent' control mechanism was absent.

  The growth control mechanism was switched on by a decrease in the sugar consumption rate and by a decrease of ATP production rate in the cells

• A significant increase in ppGpp concentration in the cells was observed during conditions when cell energy change (EC) was lower than the critical value. It was proposed that the EC value could be an effector to increase ppGpp synthesis in the cells. When the growth control mechanism was switched on in the cells having growth rate of 0.1-0.2/h, simultaneous increases of cellular concentration of ppGpp and NADPH were observed. Applying the principle of a short-term switching on of the growth control mechanism in Brevibacterium flavum and Micrococcus glutamicus cells, lysine synthesis productivity was increased by up to 1.4-1.6 g lys.HCl/l.h (control 1.0g lys.HCl/l.h).

• The Institute of Microbiology as the leading organization participated in working out the project of national programme "Production and Use of Biofuels in Latvia". The Co-ordination Council of Programme has accepted this project for presenting it to the Cabinet of Ministers.

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