MIXED SUBSTRATES IN ENVIRONMENT AND BIOTECHNOLOGICAL PROCESSES

The modern literature and own experimental data on the use of substrates' mixtures for intensification of microbial synthesis technologies of practically valuable fermentation products (ethanol, lactic acid, butanediol), primary (amino acids, n-hydroxybenzoate, triglycerides) and secondary (lovastatin, surfactants) metabolites as well as for intensification of biodegradation of aromatic xenobiotics (benzene, cresols, phenols, toluene) and pesticides (dimethoate) are presented. Special attention is paid on the molecular mechanisms that were established in recent years and underlying the phenomenon catabolic repression in Gram-positive (Bacillus subtilis) and Gram-negative (Pseudomonas, Escherichia coli) bacteria and yeast Saccharomyces cerevisiae, and on the use of these data to develop technologies for utilization of plant biomass to produce industrially important metabolites. The survival strategies of heterotrophic microorganisms in natural oligotrophic environments are considered, including the simultaneous use of multiple substrates, allowing improved kinetic characteristics that give them a competitive advantage, also provided significant metabolic/physiological flexibility. The own experimental data on the use of mixtures of growth substrates for the intensification of surfactants' synthesis of Rhodococcus erythropolis IMV Ac-5017 and Acinetobacter calcoaceticus IMV B-7241 are summarized. The dependence of the synthesis of surfactants in a mixture of energy excess (hexadecane) and energy deficient (glycerol, ethanol) substrates on the way of inoculum preparation, concentration of mono-substrates in the mixture, and their molar ratio were determined.