activities in vivo and affected the strain growth. Previous studies
had shown that L-lactic acid production using thermophilic Bacillus
sp. was growth-related. Cell growth is a major contributor to L-lactic
acid production and the final cell density plays a critical role in
improving lactic acid production performance (Zhao et al., 2010;
Wee and Ryu, 2009; Qin et al., 2009).