Abstract This study aimed to address the roles of divalent-cation transporter genes of Lactobacillus casei 2-9-5 in resisting hop bitter compound iso-α-acid. To determine the underlying mechanisms for Lactobacillus casei strains to resist iso-α-acid, RNA sequencing was performed for La. casei 2-9-5 and W2-9-5, which was an isolate of La. casei W2-9-5 derivative with a relatively weaker iso-α-acid resistance ability, in 0.012% iso-α-acid solution. Results indicated that its resistance of iso-α-acid was closely related to transmembrane transport, membrane composition and oxidative phosphorylation. Compared with La. casei W2-9-5, the expressions of the mntA, mntB and mntC genes were found to be significantly up-regulated in La. casei 2-9-5 and confirmed by RT-qPCR analysis. To examine the roles of these genes, recombinant plasmids harboring these genes were constructed and expressed in model bacteria Lactococcus lactis NZ3900. Relative to controls, the recombinant Lc. lactis containing mntB and mntC genes grew better under iso-α-acid pressure. Furthermore, the intracellular Mn2+ concentration in La. casei 2-9-5 was much higher than that in La. casei W2-9-5. Together, the data support that manganese transporter genes mntB and mntC are involved in the iso-α-acid resistance ability of La. casei strains through enhancement of intracellular Mn2+ concentrations.

中文翻译：

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啤酒腐败菌二价阳离子转运蛋白基因mntB和mntC在抗啤酒花苦味化合物异α-酸中的作用

摘要 本研究旨在探讨干酪乳杆菌2-9-5二价阳离子转运蛋白基因在抗酒花苦味化合物异α-酸中的作用。为了确定干酪乳杆菌菌株抵抗异α-酸的潜在机制，对干酪乳杆菌 2-9-5 和 W2-9-5（干酪乳杆菌 W2-9-5 的分离株）进行了 RNA 测序在0.012%的异α-酸溶液中，耐异α-酸能力相对较弱的衍生物。结果表明，其对异α-酸的抗性与跨膜转运、膜组成和氧化磷酸化密切相关。与干酪乳杆菌 W2-9-5 相比，发现 mntA、mntB 和 mntC 基因在干酪乳杆菌 2-9-5 中的表达显着上调，并通过 RT-qPCR 分析证实。为了检查这些基因的作用，构建了含有这些基因的重组质粒，并在模型细菌乳酸乳球菌 NZ3900 中表达。相对于对照，重组 Lc。含有 mntB 和 mntC 基因的乳酸菌在异α-酸压力下生长得更好。此外，La. casei 2-9-5 细胞内Mn2+ 浓度远高于La. casei W2-9-5。总之，数据支持锰转运蛋白基因 mntB 和 mntC 通过提高细胞内 Mn2+ 浓度参与 La. casei 菌株的异α-酸抗性能力。干酪 W2-9-5。总之，数据支持锰转运蛋白基因 mntB 和 mntC 通过提高细胞内 Mn2+ 浓度参与 La. casei 菌株的异α-酸抗性能力。干酪 W2-9-5。总之，数据支持锰转运蛋白基因 mntB 和 mntC 通过提高细胞内 Mn2+ 浓度参与 La. casei 菌株的异α-酸抗性能力。