Ubiquitous in the aquatic environment, sulphate-reducing bacteria (SRB) are considered one of the dominant microorganisms involved in the degradation of sulphate. This study focused on the spatial and temporal distributions of SRB in the Scirpus triquter rhizosphere sediments with a comparison to non-rhizosphere sediments and evaluated the implication of SRB to the bioavailability of metals in the Yangtze Estuary. The results showed that taking dsrB as the target gene, SRB abundances in rhizosphere sediments were significantly higher than those in non-rhizosphere sediments (P < 0.01). SRB abundances were relatively higher in April and January than other seasons. Moreover, redundancy discriminate analysis (RDA) results indicated that sulphate, pH and TOC were the major environmental factors affecting the SRB abundance in rhizosphere sediments. The concentrations of most metals were significantly related to SRB abundance, and sulphide concentrations showed a significantly positive correlation to metal concentrations, indicating metal sulphide/metal associated sulphide could be regulated by SRB. Furthermore, electron microscope analysis found that nano-sized metal sulphide particles were ubiquitous in rhizosphere sediments and could be further taken up by plants. This study provides new insights into the immobilization and removal of heavy metals and the ecological value of the sulphate-reducing bacteria in the Yangtze Estuary.

减少硫酸盐的细菌（SRB）在水生环境中无处不在，被认为是参与硫酸盐降解的主要微生物之一。本研究着眼于Scirpus triquter根际沉积物中SRB的时空分布，并与非根际沉积物进行比较，并评估了SRB对长江口金属生物利用度的影响。结果表明，以dsr B为靶基因，根际沉积物中SRB的丰度明显高于非根际沉积物中的SRB丰度（P <0.01）。4月和1月的SRB丰度相对高于其他季节。此外，冗余判别分析（RDA）结果表明，硫酸盐，pH和TOC是影响根际沉积物中SRB丰度的主要环境因素。大多数金属的浓度与SRB的丰度显着相关，硫化物的浓度与金属的浓度呈显着的正相关，表明金属硫化物/金属相关的硫化物可以由SRB调节。此外，电子显微镜分析发现，纳米级金属硫化物颗粒在根际沉积物中无处不在，并可能被植物进一步吸收。