[Effect of the pH of the medium on the growth and chemical composition of the methanol-assimilating yeast Candida boidinii].

The yeast Candida boidinii T2A was grown in a medium with methanol or glucose as a sole source of carbon and energy, and the effect of the pH of the medium on the specific growth rate, the economic coefficient and the chemical composition of the yeast was investigated in a continuous chemostat process. The graphic presentation of the specific growth rate as a function of the pH is bell-shaped and, for all practical purposes, symmetric with respect to the ordinate of the optimal pH value. The maximal, specific rate of the yeast growth is 0.24 h-1 in the case of methanol and 0.38 h-1 in the case of glucose. The maximum in the curve is observed at pH 4.0 to 5.0. The yeast grows within a wide range of pH without a change in the economic coefficient. At all the studied dilution rates for a continuous culture exceeding 0.06 h-1 and the pH from 2 to 8, the yield of yeast biomass remains almost at the same level (36-40%). The results show a change in the chemical composition of the biomass depending on the pH of the medium and the rate of the yeast growth.