Impacts of Human Activities on the Composition and Abundance of Sulfate-Reducing and Sulfur-Oxidizing Microorganisms in Polluted River Sediments.

Rui Wang,Guoqiang Zhuang,Shengjun Xu,Zhihui Bai,Yang Zhang,Na Bai,Xuliang Zhuang,Cancan Jiang

doi:10.3389/fmicb.2019.00231

Abstract

Water system degradation has a severe impact on daily life, especially in developing countries. However, microbial changes associated with this degradation, especially changes in microbes related to sulfur (S) cycling, are poorly understood. In this study, the abundance, structure, and diversity of sulfate-reducing microorganisms (SRM) and sulfur-oxidizing microorganisms (SOM) in the sediments from the Ziya River Basin, which is polluted by various human interventions (urban and agricultural activities), were investigated. Quantitative real-time PCR showed that the S cycling-related (SCR) genes (dsrB and soxB) were significantly elevated, reaching 2.60 × 107 and 1.81 × 108 copies per gram of dry sediment, respectively, in the region polluted by human urban activities (RU), and the ratio of dsrB to soxB abundance was significantly elevated in the region polluted by human agricultural activities (RA) compared with those in the protected wildlife reserve (RP), indicating that the mechanisms underlying water system degradation differ between RU and RA. Based on a 16S rRNA gene analysis, human interventions had substantial effects on microbial communities, particularly for microbes involved in S cycling. Some SCR genera (i.e., Desulfatiglans and Geothermobacter) were enriched in the sediments from both RA and RU, while others (i.e., Desulfofustis and Desulfonatronobacter) were only enriched in the sediments from RA. A redundancy analysis indicated that NH4+-N and total organic carbon significantly influenced the abundance of SRM and SOM, and sulfate significantly influenced only the abundance of SRM. A network analysis showed high correlation between SCR microorganisms and other microbial groups for both RU and RA, including those involved in carbon and metal cycling. These findings indicated the different effects of different human interventions on the microbial community composition and water quality degradation.

Highlights

Odorous black water is a crisis in lakes, rivers, or seashores, during the summer (Feng et al, 2014)
The river could be divided into three regions, an upstream region belonging to a protected wildlife reserve with little nutrients pollution, a midstream region localized near the city center and polluted by urban waste and sludge with high concentrations of organic matter and nitrogen pollutants (RU), and a downstream region polluted by runoff from farmlands with large amounts of sulfate fertilizer application (RA) (Supplementary Figure S1 and Supplementary Table S1) (Li et al, 2014; Ding et al, 2015)
The effects of various human interventions on the abundance and diversity of sulfate-reducing microorganisms (SRM) and sulfur-oxidizing microorganisms (SOM) communities were characterized in an odorous black river system

Summary

Introduction

Odorous black water is a crisis in lakes, rivers, or seashores, during the summer (Feng et al, 2014). Hydrogen sulfide together with other reduced sulfur (S) compounds are the main sources of malodor in severely degraded waters (Holmer and Storkholm, 2001; Zhang et al, 2010; Watson and Juttner, 2017). In these conditions, water is highly hypoxic, leading to the death of fish and other aquatic organisms and threatening drinking water safety. Few studies have examined microbial changes leading to the phenomenon, especially changes in microbes involved in S cycling

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Results

Discussion

Conclusion