Enhanced l-Lactic Acid Production from Biomass-Derived Xylose by a Mutant Bacillus coagulans
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Xylose effective utilization is crucial for production of bulk chemicals from low-cost lignocellulosic substrates. In this study, an efficient l-lactate production process from xylose by a mutant Bacillus coagulans NL-CC-17 was demonstrated. The nutritional requirements for l-lactate production by B. coagulans NL-CC-17 were optimized statistically in shake flask fermentations. Corn steep liquor powder and yeast exact were identified as the most significant factors by the two-level Plackett–Burman design. Steepest ascent experiments were applied to approach the optimal region of the two factors, and a central composite design was employed to determine their optimal levels. The optimal medium was used to perform batch fermentation in a 3-l bioreactor. A maximum of 90.29 g l−1 l-lactic acid was obtained from 100 g l−1 xylose in 120 h. When using corn stove prehydrolysates as substrates, 23.49 g l−1 l-lactic acid was obtained in 36 h and the yield was 83.09 %.
KeywordsBacillus coagulans Xylose l-lactic acid Lignocellulosic materials Corn stove prehydrolysates
The authors are grateful to the National Natural Science Foundation of China (31200443 and 31300487), the Natural Science Foundation of Jiangsu Province of China (BK20130970), the Program for New Century Excellent Talents in University (NCET-0988), the Excellent Youth Foundation of Jiangsu Province of China (BK2012038), the Open Project of State Key Lab of Microbial Technology of Shandong University (M201305), and a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institution for financial support.
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