• Microbiology and Biotechnology Letters
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• v.26 no.6
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• pp.476-482
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• 1998

Growth sensitivity of bifidobacteria on oxygen hindered their industrial applications so that it was necessary to select oxygen-tolerant strains. Studies on their responses to oxygen might facilitate the effective utilization of bifidobacteria in industry. Oxygen-tolerant strain of Bifidobacterium longum JI-1 was able to remove 3% dissolved oxygen within 10 min whilst oxygen-sensitive strain of B. adolescentis, slime non-former, was not. The ability to remove environmental oxygen seemed to be related to the oxygen-tolerance of bifidobacteria. Mutant B. longum ADJ-1 was induced from the B. longum JI-1 under microaerobic atmosphere. There were no differences in sugar utilization pattern, NADH oxidative enzymes and cellular fatty acid compositions between them. The maximal cell density of the mutant was a little bit reduced to 81% of that of the mother strain. However, the mutant formed thick slime layer around its cell. The layer visualized with confocal scanning laser microscopy from the mutant was 6 ${\mu}{\textrm}{m}$ in diameter but that from the mother strain was only 3 ${\mu}{\textrm}{m}$. Therefore, the improved tolerances of the mutant might come from the slime layer, indicating the increase of the layer might be one of oxygen tolerance mechanisms for bifidobacteria.

• Biomolecules & Therapeutics
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• v.24 no.5
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• pp.510-516
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• 2016

Isoegomaketone (IK) was isolated from Perilla frutescens, which has been widely used as a food in Asian cuisine, and evaluated for its biological activity. We have already confirmed that IK induced the HO-1 expression via Nrf2 activation in RAW264.7 cells. In this study, we investigated the effect of IK on the mechanism of HO-1 expression. IK upregulated HO-1 mRNA and protein expression in a dose dependent manner. The level of HO-1 mRNA peaked at 4 h after $15{\mu}M$ IK treatment. To investigate the mechanisms of HO-1 expression modulation by IK, we used pharmacological inhibitors for the protein kinase C (PKC) family, PI3K, and p38 MAPK. IK-induced HO-1 mRNA expression was only suppressed by SB203580, a specific inhibitor of p38 MAPK. ROS scavengers (N-acetyl-L-cysteine, NAC, and glutathione, GSH) also blocked the IK-induced ROS production and HO-1 expression. Furthermore, both NAC and SB203580 suppressed the IK-induced Nrf2 activation. In addition, ROS scavengers suppressed other oxidative enzymes such as catalase (CAT), glutathione S-transferase (GST), and NADH quinone oxidoreductase (NQO-1) in IK-treated RAW264.7 cells. Taken together, it can be concluded that IK induced the HO-1 expression through the ROS/p38 MAPK/Nrf2 pathway in RAW264.7 cells.

• Journal of Life Science
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• v.34 no.7
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• pp.465-475
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• 2024

Lactiplantibacillus plantarum K9 is a probiotic strain that can be utilized from various bioactive substances isolated from Protaetia brevitarsis seulensis larvae. In this study, a genetic analysis of L. plantarum K9 revealed the existence of a bacterial chromosome and three plasmids. The glycolysis pathway and pentose phosphate pathway were examined for their normal functioning via an analysis of the core metabolic pathways of L. plantarum K9. Since the key enzymes, fluctose-1,6-bisphospatase (EC: 3.1.3.11) and 6-phosphogluconate dehydratase (EC: 4.2.1.12)/2-keto-deoxy-6-phosphogluconate (KDPG) aldolase (EC: 4.2.1.55), of gluconeogenesis and the ED pathway were not identified from the L. plantarum K9 genome, we suggest that gluconeogenesis and the ED pathway are not performed in L. plantarum K9. Additionally, while some enzymes, related to fumarate and malate biosyntheses, involved in the TCA cycle were identified from L. plantarum K9, the enzymes associated with the remaining TCA cycle were absent, indicating that the TCA cycle cannot proceed. Meanwhile, based on our findings, we propose that the oxidative electron transport system performs class IIB-type (bd-type) electron transfer. In summary, we assert that L. plantarum K9 performs homolactic fermentation, executes gluconeogenesis and the pentose phosphate pathway, and carries out energy metabolism through the class IIB-type oxidative electron transport system. Therefore, we suggest that L. plantarum K9 has relatively high lactic acid production, and that it has excellent antibacterial activity, as a result, compared to other lactic acid bacterial strains. Moreover, we speculate that L. plantarum K9 has an oxidative electron transport capability, indicating that it is highly resistant to oxygen and suggesting that it has fine cultivation characteristics, which collectively make it highly suitable for use as a probiotic.