Enhancement of L-lactic acid production in Lactobacillus casei from Jerusalem artichoke tubers by kinetic optimization and citrate metabolism.
Efficient L-lactic acid production from Jerusalem artichoke tubers by Lactobacillus casei G-02 using simultaneous saccharification and fermentation (SSF) in fed-batch culture is demonstrated. The kinetic analysis in the SSF signified that the inulinase activity was subjected to product inhibition, while the fermentation activity of G-02 was subjected to substrate inhibition. It was also found that the intracellularly NOX activity was enhanced by the citrate metabolism, which increased the carbon flux of Embden-Meyerhof-Parnas (EMP) pathway dramatically, and resulted more ATP production. As a result, when the SSF was carried out at 40 degrees after the initial hydrolysis of 1 h with supplemented sodium citrate of 10g/L, L-lactic acid concentration of 141.5 g/L was obtained in 30 h with a volumetric productivity of 4.7 g/L/h. The conversion efficiency and product yield were 93.6% of the theoretical lactic acid yield and 52.4 g lactic acid/100 g Jerusalem artichoke flour, respectively. Such a high concentration of lactic acid with high productivity from Jerusalem artichoke has not been reported previously, and hence G-02 could be a potential candidate for economical production of L-lactic acid from Jerusalem artichoke at a commercial scale.
School of Food Science, JiangNan University, People's Republic of China.
Xiang-Yang
XY
Ge
He
H
Qian
Wei-Guo
WG
Zhang
D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D050260:Carbohydrate Metabolism; D019343:Citric Acid / Q000737:chemistry / Q000378:metabolism*; D005285:Fermentation; D006368:Helianthus / Q000378:metabolism / Q000382:microbiology*; D007339:Insulysin / Q000737:chemistry / Q000378:metabolism; D007700:Kinetics; D019344:Lactic Acid / Q000737:chemistry / Q000378:metabolism*; D007780:Lacticaseibacillus casei / Q000737:chemistry / Q000201:enzymology / Q000378:metabolism*; D035281:Plant Tubers / Q000378:metabolism / Q000382:microbiology
D001426:Bacterial Proteins; D019343:Citric Acid; D019344:Lactic Acid; D007339:Insulysin