Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Jimei Road 1799, Xiamen 361021, P. R. China.
Ningbo Urban Environment Observation and Station, Chinese Academy of Sciences, Zhongke Road 88, Ningbo 315800, P. R. China.
FEMS Microbiol Ecol. 2021 Mar 8;97(3). doi: 10.1093/femsec/fiab005.
Sulfate-reducing bacteria (SRB) play an important role in sulfur, iron and carbon cycling. The majority of studies have illustrated the role of SRB in biogeochemical cycling in pure cultures. In this study, we established three SRB enrichment cultures (designated HL, NB and WC) from different paddy soils and conducted a transcriptomic analysis of their metabolic characteristics under sulfate and sulfate-free conditions. In the HL cultures, there was no sulfate consumption but ferrihydrite was reduced. This indicated that bacteria in the HL samples can reduce ferrihydrite and preferentially utilize ferrihydrite as the electron acceptor in the absence of both ferrihydrite and sulfate. Sulfate consumption was equal in the NB and the WC cultures, although more ferrihydrite was reduced in the NB cultures. Transcriptomics analysis showed that (i) upregulation of O-acetylserine sulfhydrylase gene expression indicating sulfate assimilation in the WC samples; (ii) the energy conservation trithionate pathway is commonly employed by SRB and (iii) sulfate not only enhanced iron reduction by its conversion to sulfide but also promoted enzymatic electron transfer via c-type cytochromes.
硫酸盐还原菌（SRB）在硫、铁和碳循环中起着重要作用。大多数研究表明了硫酸盐还原菌在纯培养物中的生物地球化学循环中的作用。在这项研究中，我们从不同稻田中建立了三个硫酸盐还原菌富集培养物（命名为 HL、NB 和 WC），并在硫酸盐和无硫酸盐条件下对其代谢特性进行了转录组分析。在 HL 培养物中，没有硫酸盐消耗，但却还原了水铁矿。这表明 HL 样品中的细菌可以还原水铁矿，并且在既没有水铁矿也没有硫酸盐的情况下，优先利用水铁矿作为电子受体。NB 和 WC 培养物中的硫酸盐消耗相等，尽管 NB 培养物中还原了更多的水铁矿。转录组分析表明：（i）WC 样品中 O-乙酰丝氨酸硫代转移酶基因表达的上调表明硫酸盐同化；（ii）三价硫代硫酸盐能量守恒途径普遍存在于硫酸盐还原菌中；（iii）硫酸盐不仅通过转化为硫化物来增强铁还原，还通过 c 型细胞色素促进酶促电子转移。
