Fig. 4

Typical HPLC profiles of bile acids from fermentation optimization experiments. a Reference standards of TUDCA, T-7-KLCA, and TCDCA. b, c Results of feedstock optimization. d Results of M9-GY medium compared with the optimized medium. e Results of 12 h static process following 3.5 h stirring fermentation compared with 3.5 h stirring fermentation alone. f Results of separating cells from fermentation broth on TUDCA conversion during the static process