초록
A frequently used fermentation manner in lactic acid (LA) production, batch fermentation by pure cultures, has a limited practicability: low volumetric productivity and high energy consumption. In this study, continuous LA fermentation was performed in a completely stirred tank reactor at 12h HRT, inoculated with anaerobic digester sludge. Glucose (25g COD/L) was used as a feedstock and temperature was increased from 35 to 60<SUP>o</SUP>C. LA production significantly increased from 50<SUP>o</SUP>C, which was negligible up to 45<SUP>o</SUP>C, with obvious bacterial community change. At 50 and 55<SUP>o</SUP>C, LA production was maximized, reaching 23g COD/L, corresponding to 92% LA conversion efficiency. Pyrosequencing analysis showed that microbial diversity was simplified at 50-60<SUP>o</SUP>C, and the sequences closely related with Bacillus coagulans became predominant, followed by Lactobacillus fermentum. An LA-producing upflow ananerobic sludge blanket reactor was successfully developed, which enhanced the productivity up to 4.8gLA/L/h by shortening HRT to 4h.