Identification of a major facilitator superfamily protein that is beneficial to L-lactic acid production by Bacillus coagulans at low pH.
Identification of a major facilitator superfamily protein that is beneficial to L-lactic acid production by Bacillus coagulans at low pH.
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DOI：
10.1186/s12866-022-02736-2
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发表时间：
2022-12-20
期刊：
影响因子：
4.2
通讯作者：
Wang, Xiuwen
中科院分区：
文献类型：
--
作者：
Tian, Wenzhe;Qin, Jiayang;Lian, Congcong;Yao, Qingshou;Wang, Xiuwen
产物抑制是乳酸发酵中的主要问题之一。我们的前期研究表明凝结芽孢杆菌2-6是一种高效的高光学纯度L-乳酸产生菌。其突变株B。凝结蛋白Na-2对乳酸钠胁迫具有较好的抵抗力，但其抵抗机制尚不清楚。本研究对B.结果表明，在凝固人Na-2中，MFS基因编码的主要易化因子超家族（major facilitator superfamily，MFS）蛋白存在突变。在野生型（MFS-2-6）和突变型（MFS-Na-2）蛋白中发现了10个突变位点，其中T127 A和N154 T位于跨膜转运通道的中心。MFS-2-6和MFS-Na-2分别在可遗传操作的菌株B中表达。凝结物DSM 1，使用基因的天然启动子。两种MFS蛋白的表达没有影响和L-LA生产的负面影响时，控制pH值为6.0和7.0的氢氧化钠，分别。然而，在pH 5.0时，表达MFS-2-6和MFS-Na-2的菌株获得的L-LA浓度分别是对照菌株的4.2和4.6倍。在5.0的pH控制发酵期间，表达MFS-2-6和MFS-Na-2的菌株的细胞内pH值比对照菌株高约0.69和0.45。结果表明，MFS-2-6和MFS-Na-2的表达都有利于低pH下L-LA的生产，而后者的表现更好可能是由于整个发酵过程中细胞内pH更合适。本文鉴定的MFS蛋白可以提高B的能力。MFS蛋白在环境友好型L-LA生产中具有潜在的应用价值。在线版本包含补充材料，可通过10.1186/s12866-022-02736-2获得。
Product inhibition is one of the major problems in lactic acid (LA) fermentation. Our previous study revealed that Bacillus coagulans 2–6 was an efficient producer of high-optical-purity L-LA. Its mutant strain B. coagulans Na-2 has better resistance to sodium lactate stress but the resistance mechanism has not been understood. In this study, the whole-genome sequencing of B. coagulans Na-2 was performed and one mutant gene mfs coding for the major facilitator superfamily (MFS) protein was revealed by comparative genome analysis. Ten mutation sites were identified between the wild (MFS-2-6) and mutant (MFS-Na-2) proteins, among which T127A and N154T were predicted locating in the center of the transmembrane transport channel. The MFS-2-6 and MFS-Na-2 were expressed separately in a genetically operable strain, B. coagulans DSM1, using the genes’ native promoter. The expression of the two MFS proteins had no effect and a negative effect on L-LA production when the pH was controlled at 6.0 and 7.0 by sodium hydroxide, respectively. However, 4.2 and 4.6-fold of L-LA concentrations were obtained at pH 5.0 by the strains expressing MFS-2-6 and MFS-Na-2 than that by the control strain, respectively. The intracellular pH values of the strains expressing MFS-2-6 and MFS-Na-2 were approximately 0.69 and 0.45 higher than that of the control strain during pH-controlled fermentation at 5.0. Results suggest that the expression of MFS-2-6 and MFS-Na-2 were both conducive to L-LA production at low pH, while the better performance of the latter was probably due to the more appropriate intracellular pH during the whole fermentation process. The MFS protein identified here can improve the ability of B. coagulans to resist acidic environments and produce more L-LA at low pH. The MFS protein has an application potential in environment-friendly L-LA production. The online version contains supplementary material available at 10.1186/s12866-022-02736-2.
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DOI：
10.1073/pnas.1111085108
发表时间：
2011-11-22
影响因子：
11.1
作者：
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