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Highly efficient production of D-lactic acid from chicory-derived inulin by Lactobacillus bulgaricus

Xu, Qianqian, Zang, Ying, Zhou, Jie, Liu, Peng, Li, Xin, Yong, Qiang, Ouyang, Jia
Bioprocess and biosystems engineering 2016 v.39 no.11 pp. 1749-1757
Lactobacillus delbrueckii subsp. bulgaricus, biosynthesis, carbon, cost effectiveness, ethanol production, feedstocks, fermentation, fructose, grains, hydrolysis, inulin, lactic acid, saccharification, syrups
Inulin is a readily available feedstock for cost-effective production of biochemicals. To date, several studies have explored the production of bioethanol, high-fructose syrup and fructooligosaccharide, but there are no studies regarding the production of D-lactic acid using inulin as a carbon source. In the present study, chicory-derived inulin was used for D-lactic acid biosynthesis by Lactobacillus bulgaricus CGMCC 1.6970. Compared with separate hydrolysis and fermentation processes, simultaneous saccharification and fermentation (SSF) has demonstrated the best performance of D-lactic acid production. Because it prevents fructose inhibition and promotes the complete hydrolysis of inulin, the highest D-lactic acid concentration (123.6 ± 0.9 g/L) with a yield of 97.9 % was obtained from 120 g/L inulin by SSF. Moreover, SSF by L. bulgaricus CGMCC 1.6970 offered another distinct advantage with respect to the higher optical purity of D-lactic acid (>99.9 %) and reduced number of residual sugars. The excellent performance of D-lactic acid production from inulin by SSF represents a high-yield method for D-lactic acid production from non-food grains.