INFLUENCE OF THE MINERAL MEDIUM SUPPLEMENTATION IN BIOCHEMICAL ASSIMILATION AND FERMENTATION TEST

The microbial culture process conditions interfere significantly in the morphological and physiological characteristics. Study of the effects of some environmental parameters on the kinetics of growth and the pattern of product formation can provide useful knowledge to the development of fermentative processes. The purpose of this work was to evaluate the influence of supplementation of a basal medium for assimilation and fermentation of carbon sources (lactose, glucose and galactose) by yeasts isolated from milk processing plants. Six isolates of microorganisms (P1, PI1, PI3, SR, 1TE, STFB) were analyzed. The results demonstrated that in mineral medium, no strain can ferment enough to completely fill the Durham tube with gas. In this condition, for all carbon sources, none of the isolates tested were able to present strongly positive results. When the mineral medium was supplemented with yeast extract and bacteriological peptone, the isolates had a more efficient fermentation allowing the evaluation of kinetic parameters of affinities for mono- and di-saccharides.