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J Biosci Bioeng. 2019 Jul 29. pii: S1389-1723(19)30076-3. doi: 10.1016/j.jbiosc.2019.06.017. [Epub ahead of print]

Suppression of lactate production by using sucrose as a carbon source in lactic acid bacteria.

Author information

1
Graduate School of Science and Engineering, Kansai University, 3-3-35 Yamate, Suita, Osaka 564-8680, Japan. Electronic address: k487506@kansai-u.ac.jp.
2
Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan. Electronic address: risa.harada1110@gmail.com.
3
Food Microbiology Research Laboratories, R&D Division, Meiji Co., Ltd., 1-29-1 Nanakuni, Hachiouji, Tokyo 192-0919, Japan. Electronic address: nobuo.yoda@meiji.com.
4
Department of Life Science and Biotechnology, Faculty of Chemistry, Materials and Bioengineering, Kansai University, 3-3-35 Yamate, Suita, Osaka 564-8680, Japan. Electronic address: shino.ya@kansai-u.ac.jp.
5
Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan. Electronic address: fukusaki@bio.eng.osaka-u.ac.jp.
6
Department of Life Science and Biotechnology, Faculty of Chemistry, Materials and Bioengineering, Kansai University, 3-3-35 Yamate, Suita, Osaka 564-8680, Japan. Electronic address: katakura@kansai-u.ac.jp.

Abstract

Lactic acid bacteria (LAB) grow by producing lactate from sugar. However, the accumulation of lactate inhibits their growth. Here, the lactate productivity per cell in a semi-solid medium prepared with a chlorella powder in several LAB strains was much lower than that in the conventional MRS medium. Furthermore, the lactate production was suppressed not only in semi-solid medium, but also in chlorella liquid medium. The lactate productivity by Lactococcus lactis subsp. lactis NBRC 12007 in the chlorella liquid medium and MRS medium was 3.0 and 6.9 g-lactate·g-cell-1, respectively. The productivity of lactate in the chlorella liquid medium decreased to 44% of that in MRS medium. Gas chromatography/mass spectrometry (GC/MS) analysis of the culture supernatants revealed that the utilization of sucrose in the chlorella powder led to the suppression of lactate production. Comparison of the metabolites extracted from the cells indicated that the two ATP generating pathways, the arginine deiminase pathway and the decarboxylation reaction of glutamate and GABA, which are usually repressed by glucose, are activated in chlorella medium. It was considered that these pathways which do not require NAD+ for generation of ATP are not repressed when sucrose is used as a carbon source. Thus, the utilization of these pathways results in the suppression of the lactate production.

KEYWORDS:

Chlorella; Glucose repression; Lactic acid bacteria; Metabolome; Redox balance; Sucrose

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