SVIBOR - Project code: 4-07-012


Strossmayerov trg 4, HR - 10000 ZAGREB
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Project code: 4-07-012

Physiological activity of native and r-DNA microorganisms

Main researcher: MARIĆ, VLADIMIR (150706)

Type of research: basic
Duration from: 04/01/91. to 04/01/96.

Papers on project (total): 171
Papers on project quoted in Current Contents: 39
Institution name: Prehrambeno-biotehnološki fakultet, Zagreb (58)
Department/Institute: Department of Biochemical Engineering
Address: Pierottijeva 6/IV
City: 10000 - Zagreb, Croatia

Summary: In order to collect and extend the knowledge about the influence of the environment on the physiological activity of native and r-DNA microorganisms in the state of rest, growth and multiplication, the research will be done on various techniques of cultivation, separation, and application of microbial biomasses. Cell constituents will be defined that can serve as indicators of the physiological activity of the cells in the resting as well as in the growth phase. The influence of the nutrient medium, type of process, specific rates (of growth, supstrate consumption and product synthesis) in rich and poor media, as well as techniques for separation, concentration and preservation of microbial biomasses on the parameters of physiological activity will be explored. Based on these parameters the stability of technological characteristics of r-DNA microorganisms will be checked out in laboratory scale experiments on production of microbial biomass and various metabolites. In addition, chemical and physical techniques for plasmid stabilization will be explored. On the basis of the results of this research the mathematical model will be established to predict the physiological activity of the wild-type and r-DNA microorganisms in the production of metabolites or use of biomasses as potential starter cultures.

Keywords: r-DNA microorganisms, physiological activity, genetical stability, metabolites

Research goals: During the growth microbial cell synthesis a simple and a very complex compaunds. A synthesis is directed by enzymes which are regulated by the control mechanisms coded in DNA. Therefore, a modern biotechnology uses genetically modofied microorganisms. The aim of this research was to cellect and extend the knowledge of the influence of the environment on physiological activity of native and rDNA microorganism during: a) The state of rest (maintain of microbial biomasses in fresh, frozen or freeze-dried state), b) Growth and multiplication in aim of biomass or metabolite production in batch, semicontinuous and continuous process, c) Preparations and use of immobilized cells, d) Development of the specific process of cultivation, recovery, drying or freeze-drying of selected bacterial starter cultures (e.g. lactic and azotofixing bacteria), e) Construction and study of new type of bioreactor for the cultivation of microbial starter cultures. Expected results are: 1. definition of cell constituents by whose presence or particular concentration the physiological capability of resting or activly growing microbial cells is determined (enabling, in such a way, the predictability of cells application to potential microbial processes, 2. A practical stability control of the technological characteristic of rDNA microorganisms, in microbial production of biomass and different metabolites, 3. Comparison of physiological activity and productivity of native and rDNA microorganisms in production of biomass and metabolites, 4. Improved procedure of laboratory production of selected microbial starter culture, 5. Laboratory model of new type of horizontal tubular bioreactor and development of multiparameter mathematical model.

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Last update: 10/05/95