Abstract:

The decrease of environmental pH will affect the biochemical performance of sulfate reduction system, thus enhancing the tolerance of the system under acid stress condition has received extensive attention. In this study, an efficient sulfate-reducing bacteria (SRBs) community was constructed. Using the pure culture system inoculated with Desulfovibrio as the control group, batch experiments were carried out to investigate the effects of pH condition on the microbial growth and sulfate reduction performance of the systems, and to elucidate the physiological responses of the system microorganisms to acid stress. The results showed that the growth of bacteria and sulfate reduction reaction in the pure culture system were significantly inhibited by the decrease of pH. When the pH dropped to 5.0, the bacterial survival rate of the system was less than 10%, and the system lost its sulfate reduction function essentially. In contrast, the microorganisms in the SRBs system could improve the system resistance to acid stress through increasing the activity of ATP hydrolysis enzyme (H⁺-ATPase), producing stress proteins, adjusting the composition and distribution of fatty acids in the cell membrane, etc. After a 7d growth adaptation period, the SRBs system achieved sulfate reduction attaining a SO{}_{\mathrm{4}}^{\mathrm{2}-} removal rate of 30.90% and showed certain advantages in acid resistance. Furthermore, high-throughput sequencing technology was employed to analyze the response of the microbial community in the SRBs system to pH changes. It was found that acid stress had no significant effects on the α diversity of the microbial community in the SRBs system (p>0.05), but it altered the composition of the microbial community structure. The relative abundances of Bacillus and Clostridium increased significantly (26.26% and 5.14%, respectively), becoming the dominant bacterial genera. The research results revealed the adaptive regulatory mechanism of the SRBs system in weak acid environments, thereby providing a theoretical reference for the stable operation of biochemical systems under low pH conditions.

Key words: sulfate reduction, acid stress, bacteria community, response

摘要：

环境pH降低会影响硫酸盐还原系统的生化性能，因此提升体系在酸胁迫条件下的耐性受到广泛关注。本研究通过构建高效的硫酸盐还原菌群（SRBs），以接种脱硫弧菌的纯菌体系作为对照组，利用菌群体系开展批式试验，研究了不同pH条件对系统微生物生长和硫酸盐还原性能的影响，解析了体系微生物对酸胁迫的生理应答。结果表明，随着pH的降低，纯菌体系的细菌生长和硫酸盐还原反应受到了明显抑制，pH降至5.0后体系细菌存活率不到10%，基本丧失硫酸盐还原功能。相比之下，SRBs体系微生物能够通过提高ATP水解酶（H⁺-ATPase）活性、产生应激蛋白、调节细胞膜脂肪酸组成及分布等途径提高系统抵御酸胁迫能力，在经过7天的生长适应期后逐步实现SO{}_{\mathrm{4}}^{\mathrm{2}-}还原，达到30.90%的SO{}_{\mathrm{4}}^{\mathrm{2}-}去除率，表现出一定的耐酸优势。进一步采用高通量测序技术分析SRBs体系中微生物群落对pH变化的响应，发现酸胁迫对SRBs体系微生物α多样性的影响并不显著（p>0.05），但改变了系统微生物群落结构组成，其中芽孢杆菌属Bacillus、梭菌属Clostridium等的相对丰度显著升高（分别为26.26%、5.14%），成为了优势菌属。研究结果揭示了弱酸环境中SRBs体系的适应性调控机制，从而为生化系统在低pH条件下的稳定运行提供理论参考。

关键词: 硫酸盐还原, 酸胁迫, 菌群, 响应