Lin Xiaobao, Qi Yanli, Yan Dongni, Liu Hui, Chen Xiulai, Liu Liming
State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, China.
Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi, Jiangsu, China.
Appl Environ Microbiol. 2017 Aug 17;83(17). doi: 10.1128/AEM.00972-17. Print 2017 Sep 1.
is a promising microorganism for organic acid production. The present study aimed to investigate the role of Mediator complex subunit 3 (Med3p) in protecting under low-pH conditions. To this end, genes and were deleted, resulting in the double-deletion Δ strain. The final biomass and cell viability levels of Δ decreased by 64.5% and 35.8%, respectively, compared to the wild-type strain results at pH 2.0. In addition, lack of Med3ABp resulted in selective repression of a subset of genes in the lipid biosynthesis and metabolism pathways. Furthermore, C18:1, lanosterol, zymosterol, fecosterol, and ergosterol were 13.2%, 80.4%, 40.4%, 78.1%, and 70.4% less abundant, respectively, in the Δ strain. In contrast, the concentration of squalene increased by about 44.6-fold. As a result, membrane integrity, rigidity, and H-ATPase activity in the Δ strain were reduced by 62.7%, 13.0%, and 50.3%, respectively. In contrast, overexpression of increased the levels of C18:0, C18:1, and ergosterol by 113.2%, 5.9%, and 26.4%, respectively. Moreover, compared to the wild-type results, dry cell weight and pyruvate production increased, irrespective of pH buffering. These results suggest that regulates membrane composition, which in turn enables cells to tolerate low-pH stress. We propose that regulation of Med3ABp may provide a novel strategy for enhancing low-pH tolerance and increasing organic acid production by The objective of this study was to investigate the role of Mediator complex subunit 3 (Med3ABp) and its regulation of gene expression at low pH in We found that Med3ABp was critical for cellular survival and pyruvate production during low-pH stress. Measures of the levels of plasma membrane fatty acids and sterol composition indicated that Med3ABp could play an important role in regulating homeostasis in We propose that controlling membrane lipid composition may enhance the robustness of for the production of organic acids.
是一种有潜力用于生产有机酸的微生物。本研究旨在探究中介体复合物亚基3（Med3p）在低pH条件下对[微生物名称未给出]的保护作用。为此，删除了[基因名称未给出]和[基因名称未给出]基因，得到双缺失Δ菌株。与野生型菌株在pH 2.0时的结果相比，Δ菌株的最终生物量和细胞活力水平分别下降了64.5%和35.8%。此外，缺乏Med3ABp导致脂质生物合成和代谢途径中的一部分基因受到选择性抑制。此外，在Δ菌株中，C18:1、羊毛甾醇、酵母甾醇、粪甾醇和麦角甾醇的丰度分别降低了13.2%、80.4%、40.4%、78.1%和70.4%。相比之下，角鲨烯的浓度增加了约44.6倍。结果，Δ菌株中的膜完整性、刚性和H - ATP酶活性分别降低了62.7%、13.0%和50.3%。相比之下，[基因名称未给出]的过表达使C18:0、C18:1和麦角甾醇的水平分别提高了113.2%、5.9%和26.4%。此外，与野生型结果相比，无论pH缓冲情况如何，干细胞重量和丙酮酸产量均增加。这些结果表明，[微生物名称未给出]调节膜组成，进而使细胞能够耐受低pH胁迫。我们提出，对Med3ABp的调控可能为增强[微生物名称未给出]的低pH耐受性和提高有机酸产量提供一种新策略。本研究的目的是探究中介体复合物亚基3（Med3ABp）在[微生物名称未给出]中低pH条件下的作用及其对基因表达的调控。我们发现Med3ABp在低pH胁迫期间对细胞存活和丙酮酸生产至关重要。对质膜脂肪酸水平和甾醇组成的测量表明，Med3ABp可能在调节[微生物名称未给出]的稳态中发挥重要作用。我们提出，控制膜脂组成可能增强[微生物名称未给出]生产有机酸的稳健性。
