[The effect of the nutritional sources on the synthesis of exopolysaccharides and amino acids by Bacillus subtilis strains].

Dynamics of cell biomass accumulation and secretion to the medium extracellular polysaccharides and amino acids has been studied in Bacillus subtilis cultures No No 39 and 51 used to produce healing biopreparations--probiotics. The investigation data indicate to certain relation between these processes. EPS secretion in the studied cultures proceeded parallel with their growth and started in the logarithmic phase. Maximum EPS yield was observed by the beginning of the stationary phase after 10-12 h of growth. A successible change in the amino acid content in the medium was observed in the growth process of the studied bacteria: the bacteria first consumed amino acids of the initial medium and then excreted amino acids synthesized into the medium. Under the active production of EPS the content of extracellular amino acids in the medium was inconsiderable. The content of EPS was lower during accumulations of high concentrations of extracellular amino acids. Role of the medium components in regulation of the studied processes has been shown. The ratio C:N in the medium was of essential significance. The C:N ratio 2.0-3.0:1.0 was optimal both for the growth and secretion of EPS by the studied cultures while that of 1.0-1.5:1.0 was optimal for production of the extracellular amino acids. The increase of C:N ratio resulted in the decrease of metabolites secretion by the cultures.