The application of sulfate-reducing bacteria (SRB) shows great potential in the anaerobic biological treatment of acid mine wastewater; therefore, it has attracted much attention. The low pH in acidic wastewater affects the growth and reducing power of SRB. To uncover the mechanism underlying the reduction efficiency of SRB under acidic conditions, in this study, transcriptomic analysis was performed with Desulfovibrio vulgaris ATCC 7757 under three different pH conditions (pH 4.0, 5.5 and 7.0) and in the initial inoculation, logarithmic growth and plateau phases. Our results showed that ATCC 7757 still had biological activity at pH 4.0 and exhibited gene expression patterns at pH 4.0 that were different from those at pH 5.5 and pH 7. Importantly, the gene expression pattern was similar between pH 5.5 and pH 7. Transcriptomic analysis identified differentially expressed genes that affected the growth of ATCC 7757 under pH 7.0 at 22 h compared to 15 h; 196 of these genes were upregulated and 575 were downregulated. These differentially expressed genes were mainly enriched in genetic information processing and metabolism. Additionally, we identified 57 candidate genes associated with low-pH tolerance. Adaptation to low pH was reflected by an increase in the expression of genes involved in cell membrane structure and proton transport. The expression of genes involved in the reduction process decreased, including the genes DVU0499 and sat, which encode proteins that affect the sulfate reduction process. Both gene activities were validated by qPCR. Our results will contribute to further promoting the reducing power of SRB in acid mine wastewater and the development of successful bioremediation strategies.

中文翻译：

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寻常脱硫弧菌 ATCC 7757 酸应激反应的转录组分析

硫酸盐还原菌（SRB）在酸性矿山废水厌氧生物处理中的应用显示出巨大的潜力；因此，它引起了很多关注。酸性废水中的低pH值影响SRB的生长和还原能力。为了揭示酸性条件下 SRB 还原效率的潜在机制，在本研究中，使用 Desulfovibrio vulgaris ATCC 7757 在三种不同的 pH 条件（pH 4.0、5.5 和 7.0）以及初始接种、对数生长和平台期进行转录组学分析阶段。我们的结果表明，ATCC 7757 在 pH 4.0 下仍然具有生物活性，并且在 pH 4.0 下表现出与 pH 5.5 和 pH 7 不同的基因表达模式。重要的是，pH 5.5 和 pH 7 之间的基因表达模式相似。转录组学分析鉴定了影响 ATCC 7757 在 pH 7.0 下 22 小时与 15 小时生长的差异表达基因；这些基因中有 196 个被上调，575 个被下调。这些差异表达基因主要富集于遗传信息处理和代谢。此外，我们确定了 57 个与低 pH 耐受性相关的候选基因。对低 pH 的适应反映为参与细胞膜结构和质子转运的基因表达的增加。参与还原过程的基因表达降低，包括基因 DVU0499 和 sat，它们编码影响硫酸盐还原过程的蛋白质。两种基因活性均通过 qPCR 验证。