不同pH值条件下硫酸盐还原菌组成及硫酸盐还原机制分析

【目的】从海洋沉积物中富集获得硫酸盐还原菌群，改变pH值进行培养，分析pH值对硫酸盐还原性质的影响，明确菌群组成和进行硫酸盐还原功能基因预测，探究硫酸盐还原机制。【方法】分析硫酸盐还原菌群在不同pH值条件下的硫酸盐还原率，在此基础上，利用高通量测序技术和PICRUSt软件分析硫酸盐还原菌群优势菌组成及硫酸盐还原相关基因相对丰度。【结果】硫酸盐还原菌群在不同pH值培养条件下的生长和硫酸盐还原率出现显著变化(P<0.01)，在pH 5.0时达到峰值，分别为0.34±0.01和96.52%±0.44%。高通量测序数据显示，pH 5.0时菌群丰富度和多样性最高，优势菌属为假单胞菌(Pseudomonas)和芽孢杆菌(Bacillus)，相对丰度较高的基因为同化性硫酸盐还原相关基因。【结论】硫酸盐还原菌富集生长的最适pH 5.0，在此条件下的高硫酸盐还原率由同化性硫酸盐还原途径主导，为揭示硫酸盐还原机制提供了实验支持，并拓宽了硫酸盐还原菌实践应用方面的种质资源。

Dominant sulfate-reducing bacteria at different pH and mechanism of sulfate reduction

Objective] To analyze the influence of pH on sulfate-reducing properties of sulfate-reducing bacteria enriched from marine sediments, identify the bacterial community composition, predict the key genes of sulfate reduction, and explore the mechanism of sulfate reduction. Methods] The sulfate reduction rates of sulfate-reducing bacteria at different pH conditions were determined. On this basis, high-throughput sequencing and PICRUSt were employed to analyze the dominant sulfate-reducing bacteria and the relative abundance of sulfate-reducing genes. Results] The biomass (OD₆₀₀) and sulfate reduction rate of sulfate-reducing bacteria varied significantly under different pH conditions (P<0.01) and reached their peak values (0.34±0.01 and 96.52%±0.44%, respectively) at pH 5.0. According to the high-throughput sequencing data, the abundance and diversity of bacteria were the highest at pH 5.0. The dominant bacteria were Pseudomonas and Bacillus, and the assimilatory sulfate reduction-related genes had higher abundance. Conclusion] Sulfate-reducing bacteria are suitable to be enriched and cultured at pH 5.0. Under this condition, the high sulfate reduction rate is attributed to the assimilatory sulfate reduction pathway. The findings provide experimental support for revealing sulfate reduction mechanism and broaden the germplasm resources of sulfate-reducing bacteria for application.