宁夏第三排水沟底泥细菌群落结构特征和空间分布

Microbial community structure and spatial distribution in sediment of the Third Drainage Ditch in Ningxia

摘要:

【背景】微生物对环境有指示作用，微生物群落组成是水环境的研究热点之一。【目的】探究宁夏第三排水沟底泥细菌群落结构及空间分布。【方法】在底泥理化性质分析的基础上，采用Miseq PE300测序平台对沟道及主要支流共11个采样点的表层底泥细菌进行16S rRNA基因扩增子测序。【结果】三排底泥呈弱碱性，底泥有机碳、全氮、全磷、氨氮和硝态氮等理化指标存在空间差异。平罗县段底泥有机碳、全氮和全磷均低于贺兰县和惠农区；下游惠农区段底泥细菌的物种丰富度和多样性明显高于上游贺兰县段，十二分沟与干流差异较明显。三排底泥优势细菌菌门为变形菌门(Proteobacteria，24.41%–44.40%)、绿弯菌门(Chloroflexi，5.46%-17.55%)、放线菌门(Actinobacteria，9.12%–21.21%)、拟杆菌门(Bacteroidetes，6.96%–13.10%)、热脱硫杆菌门(Thermodesulfobacteria，3.40%-12.20%)、厚壁菌门(Firmicutes，3.31%–14.61%)和酸杆菌门(Acidobacteria，2.00%-9.77%)。优势菌属为硫杆菌属(Thiobacillus，6.73%)和norank_f__Steroidobacteraceae(4.28%)。十二分沟底泥细菌群落组成与三排差别较大，惠农区底泥细菌群落组成比较接近。对底泥细菌群落与环境因子的冗余分析显示，全氮、氨氮和硝态氮对底泥细菌群落结构影响较大。【结论】三排底泥细菌群落存在明显的空间差异，而且受氮素影响较大，应进一步对三排氮循环微生物开展深入研究。

Abstract:

[Background] Microorganisms play an indicative role in the environment, and the composition of microbial community is one of the research hotspots in water environment. [Objective] To explore the bacterial community structure and spatial distribution in the sediment of the Third Drainage Ditch in Ningxia. [Methods] The physicochemical properties of the sediment samples were analyzed, and the 16S rRNA gene amplifiers of bacteria in surface sediments from 11 sampling sites in gullies and main tributaries were sequenced by high-throughput sequencing technology. [Results] The sediment of the Third Drainage Ditch had weak alkalinity and spatial differences in physicochemical properties including organic carbon, total nitrogen, total phosphorus, ammonium nitrogen and nitrate nitrogen. The concentrations of organic carbon, total nitrogen, and total phosphorus in the sediment of Pingluo section were lower than those in Helan and Huinong sections. The richness and diversity of bacteria in the sediment of Huinong section (in the lower reaches) were significantly higher than those in Helan section (in the upper reaches). The dominant phyla were Proteobacteria (24.41%–44.40%), Chloroflexi (5.46%–17.55%), Actinobacteria (9.12%–21.21%), Bacteroidetes (6.96%–13.10%), Thermodesulfobacteria (3.40%–12.20%), Firmicutes (3.31%–14.61%), and Acidobacteria (2.00%–9.77%). The dominant genera were Thiobacillus (6.73%) and norank_f__Steroidobacteraceae (4.28%). The bacterial community composition in the sediment of Shi’er tributary was much different from that of the Third Drainage Ditch, while the composition was similar among the sampling sites in Huinong section. The redundancy analysis of bacterial community and environmental factors showed that total nitrogen, ammonium nitrogen and nitrate nitrogen had great influence on bacterial community structure in the sediment. [Conclusion] The bacterial community in the sediment of the Third Drainage Ditch showed obvious spatial differences and was greatly affected by nitrogen. The microorganisms involved in nitrogen cycle remain to be studied.