Abstract: Bacillus coagulans is a wonderful L-lactic acid producer. In this study, two B. coagulans strains, B. coagulans NL01 and XZL4, were taken as examples to investigate the effects of nitrogen source and inorganic salt on L-lactic acid production. In order to reduce the cost of culture media, 5 kinds of organic nitrogen, 2 kinds of inorganic nitrogen, and 4 kinds of inorganic salt were selected to investigate their effects on fermentation. The results showed that yeast exact was the best nitrogen source, but its effects on B.?coagulans NL01 and XZL4 were different. Compared with previous reports, the most exciting result was that potassium dihydrogen phosphate could intensively improve the concentration of L-lactic acid even instead of partial yeast exact. And this would distinctly reduce the cost of culture media.

Key words: Bacillus coagulans, Organic nitrogen, Inorganic nitrogen, Inorganic salt, L-Lactic acid