[Qualitative and quantitative composition of acids formed by bifidobacteria]

The dynamics of acid production in 18 strains of bifidobacteria, belonging to 5 different species, has been studied Bifidobacteria have been found to produce 3 acids, lactic, acetic and formic, in the process of their metabolism. The lactic acid/acetic acid quantitative ratio varies, depending on the culture medium on the average, 1:2 in Blaurock medium, 1:5 in milk hydrolysate medium. Various strains have also been found to differ in the dynamics of acid production with respect to the amounts of lactic and acetic acids. The study has shown that, despite the active production of acids for a period of up to 72 hours, a decrease in the pH of the medium is observed for not more than 48 hours. The existence of a specific mechanism permitting bifidobacteria to regulate the acidity of their environment is supposed.