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Glucose metabolic flux distribution of Lactobacillus amylophilus during lactic acid production using kitchen waste saccharified solution

Authors

  • Jianguo Liu,

    1. School of Civil and Environmental Engineering, University of Science and Technology Beijing, Beijing, China
    2. Key Laboratory of Educational Ministry for High Efficient Mining and Safety in Metal Mine, University of Science and Technology Beijing, Beijing, China
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  • Qunhui Wang,

    Corresponding author
    1. Key Laboratory of Educational Ministry for High Efficient Mining and Safety in Metal Mine, University of Science and Technology Beijing, Beijing, China
    • School of Civil and Environmental Engineering, University of Science and Technology Beijing, Beijing, China
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  • Hui Zou,

    1. School of Civil and Environmental Engineering, University of Science and Technology Beijing, Beijing, China
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  • Yingying Liu,

    1. Biological laboratory, National Institute of Metrology P.C.China, Beijing, China
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  • Juan Wang,

    1. School of Civil and Environmental Engineering, University of Science and Technology Beijing, Beijing, China
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  • Kemin Gan,

    1. School of Civil and Environmental Engineering, University of Science and Technology Beijing, Beijing, China
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  • Juan Xiang

    1. School of Civil and Environmental Engineering, University of Science and Technology Beijing, Beijing, China
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  • Funding Information This research was supported by the National Natural Science Foundation (No. 50978028 and 51278050).

For correspondence. E-mail wangqh59@sina.com; Tel. (+86) 10 6233 2778; Fax (+86) 10 6233 2778.

Summary

The 13C isotope tracer method was used to investigate the glucose metabolic flux distribution and regulation in Lactobacillus amylophilus to improve lactic acid production using kitchen waste saccharified solution (KWSS). The results demonstrate that L. amylophilus is a homofermentative bacterium. In synthetic medium, 60.6% of the glucose entered the Embden–Meyerhof–Parnas (EMP) to produce lactic acid, whereas 36.4% of the glucose entered the pentose phosphate metabolic pathway (HMP). After solid–liquid separation of the KWSS, the addition of Fe3+ during fermentation enhanced the NADPH production efficiency and increased the NADH content. The flux to the EMP was also effectively increased. Compared with the control (60.6% flux to EMP without Fe3+ addition), the flux to the EMP with the addition of Fe3+ (74.3%) increased by 23.8%. In the subsequent pyruvate metabolism, Fe3+ also increased lactate dehydrogenase activity, and inhibited alcohol dehydrogenase, pyruvate dehydrogenase and pyruvate carboxylase, thereby increasing the lactic acid production to 9.03 g l−1, an increase of 8% compared with the control. All other organic acid by-products were lower than in the control. However, the addition of Zn2+ showed an opposite effect, decreasing the lactic acid production. In conclusion it is feasible and effective means using GC-MS, isotope experiment and MATLAB software to integrate research the metabolic flux distribution of lactic acid bacteria, and the results provide the theoretical foundation for similar metabolic flux distribution.

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