LACTIC ACID PRODUCTION BY A RUMEN BACTERIUM CULTIVATED ON CHEMICALLY DEFINED MEDIUM WITH AMMONIA AS NITROGEN SOURCE

摘要

A chemically defined medium simulating sugarcane juice was used to study and model the fermentation characteristics of lactic acid production by Streptococcus bovis under nitrogen-limited conditions. The model accurately predicted the behaviour of S. bovis under steady state continuous stirred tank reactor conditions (CSTR). Our studies show that there is a trade off between productivity and yield. The specific productivity increased with growth rate. However, the higher the growth rate, the lower the yield of lactic acid. A high substrate concentration combined with low dilution rate results in high lactic acid productivity and yield and a low cell yield.