[Influence of products of thermophilous methane fermentation on the mixed lactic acid bacterial culture].

The effect of products resulting from thermophilous methane fermentation on the accumulation and ratio of different lactic acid bacteria (Str. lactis, Str. cremoris, Str. diacetilactis, Str. diacetil. var. acetoinicus, Leuc. citrovorum8 L. plantarum) was investigated upon their combined cultivation in milk and serum. In combined cultivation of the streptococcal culture the rate of growth of a single strain differed from that in separate cultivation. Str. cremoris was accumulated with the highest rate during its separate cultivation and with the lowest rate during its combined cultivation. An addition of products of thermophilous methane fermentation to the combined culture of streptococci of different strains increased the growth rate and accumulation of each strain. At the same time the products influenced differently the quantitative ratios of various strains in the resulting biomass. For instance, the relative content of Str. cremoris and Leuc. citrovorum decreased insignificantly and that of Str. lactis and Str. diacetil. var. acetoin.increased. The combined cultivation of the five streptococcal strains with L. plantarum in the medium containing no additions of thermophilous methane fermentation products increased the relative content of L. plantarum from the beginning of fermentation. In the medium containing the additions of this parameter varied sinusoidally with a minimum of 6 to 9 hours. Possible mechanisms of these changes are discussed.