High-Titer L-lactic Acid Production by Fed-Batch Simultaneous Saccharification and Fermentation of Steam-Exploded Corn Stover
Liheng Deng, Changsheng Su, Yilu Wu, Qiang Xue, Changwei Zhang, Yong Wang, Bin Wang, Di Cai
Abstract
Steam explosion (SE) is an effective lignocellulose pretreatment technology for second-generation L-lactic acid (L-LA) production. In this study, targeted to produce high-concentration L-LA from corn stover (CS), the fed-batch simultaneous saccharification and fermentation (SSF) of acidic, SE-pretreated CS was developed and demonstrated in a 5 L scale bioreactor under non-strict conditions (without detoxification and sterilization). The results indicated that the fed-batch SSF, with a simple pH control, realized a higher tolerance of the strains to the toxic by-products of hydrolysate, in comparison to the conventional sequential hydrolysis and fermentation (SHF), allowing for 153.8 g L−1 of L-LA production, along with a productivity of 1.83 g L−1 h−1 in a system with a total of 40% (w/v) solid loading. The mass balance indicated that up to 449 kg of L-LA can be obtained from 1 t of dried CS. It exhibited obvious superiorities and laid down a solid foundation for the industrialization of second-generation L-LA production.