L-Lactic acid fermentation by Enterococcus faecium: a new isolate from bovine rumen

To obtain a novel adaptable stain that can produce enantioselective L-lactic acid efficiently, reduce the operational cost of fermentation process and be suitable for scale production.

Enterococcus faecium S.156 produced 126 g L-lactic acid/l with high optical purity (99.7 %), high productivity (5.25 g/l.h) and a conversion ratio >90 %. L-lactic acid production remained steady from 32 to 40 °C and at pH values from 5.5 to 6.5. O2 made no difference to both biomass growth and the L-lactic acid fermentation. 8 mg folic acid/l combined with 2 mM Fe(2+) substituted for 6 g yeast extract/l, which is a cost-saving.

The special characteristics and economic traits of E. faecium S.156 make it suitable for industrial-scale production of L-lactic acid.