Bifidobacterium sp. 고농도 성장을 위한 환경인자 및 세포활성도 최적화

Abstract

For the industrial use of Bifidobacterium sp., maintaining cell viability is crucial along with the high cell concentration through fermentation optimization. The effects of initial glucose concentration, lactic acid concentration, pH and culture temperature on cell growth were investigated to optimize the environmental factors. In addition, the batch and fed-batch cultivation were performed to evaluate the correlation between the cell concentration based on the absorbance and the viable cell number. Both B. infantis and B. bifidum showed the highest cell growth rates at low glucose levels and the specific growth rate decreased with increasing glucose concentrations. The growth rate of B. bifidum was reduced with increasing glucose concentration, but the maximum cell concentration was increased. However, B. infantis showed lower maximum cell concentration in the higher glucose concentration. The impacts of lactic acid, pH and temperature of both B. infantis and B. bifidum were similar to those of most lactic acid bacteria. However, B. bifidum showed a more resilience within the same range of each environmental factor showing continuous growing at low specific growth rate even when B. infantis stopped growing. The number of viable cells of B. infantis was dramatically reduced even though the absorbance remained constant. In particular, the number of viable cells and the number of viable cells per absorbance decreased to 1/7 and 1/10 as the fed-batch culture progressed. Meantime, once the maximum viable cell number was reached, B. bifidum maintained the constant viable cell number and viable cell number per absorbance were maintained.