Efficient l-lactic acid production from sweet sorghum bagasse by open simultaneous saccharification and fermentation

Abstract

As an important industrial feedstock with various applications, most lactic acid is currently fermented from refined food carbohydrates. To research the feasibility of using non-food feedstock for L-lactic acid production, sweet sorghum bagasse (SSB) as an important lignocellulosic biomass was used by Bacillus coagulans LA1507 in open simultaneous saccharification and fermentation (SSF). In the fed-batch SSF process with a stepwise controlled pH, a cellulase dose of 25 FPU g⁻¹ pretreated SSB and 15 g L⁻¹ corn steep liquor powder (CSLP) were used to produce L-lactic acid from 17.5% (w/v) stover, and B. coagulans LA1507 provided a balanced result which contained a product titer of 111 g L⁻¹, a yield of 0.437 g g⁻¹ crude SSB and an average productivity of 1.59 g L⁻¹ h⁻¹. The process introduces an effective way to produce L-lactic acid from abundant SSB.