Characterization Of Microbial Community Structure And Functional Genes In A High Arsenic Groundwater System From The Hetao Basin,Inner Mongolia

Arsenic is a ubiquitous toxic element.Arsenic-contaminated groundwater is a global public health problem affecting millions of people.The Hetao basin in Inner Mongolia is a serious polluted area with high arsenic groundwater in China.The microbial activity has a great impact on the mobilization and transformation of arsenic in the groundwater system,especially the microbial metabolism of iron?Fe?,sulphur?S?and arsenic?As?.However,the effect of microbial community structure and function on the mobilization and biotransformation processes of Fe-S-As and underlying molecular mechanisms in the high arsenic groundwater system are still unknown.In this disseration,we selected the Hetao Basin of Inner Mongolia,a typical high arsenic groundwater area in China as the study area.Using 16S rRNA high-throughput sequencing and metagenomic approaches to analyze groundwater and sediment samples from the Hetao basin,we aim to profile the microbial community and functional genes in the high arsenic groundwater system,and investigate the microbial processes in arsenic biotransformation and their underlying molecular mechanisms.The main conclusions were obtained as follows:?1?16S rRNA sequencing results showed that Acinetobacter and Pseudomonas were the dominant microorganisms in the high arsenic groundwater in the Hetao Basin,Inner Mongolia.As _Total,Fe _Total,Fe²⁺,Mn_Totalotal were signigificantly correlated to the microbial community structure of the high-arsenic groundwater in the plain area?p<0.05?,demonstrating their potential impact on the diversity and composition structure of the microbial community.The functional bacteria related to the sulfate reduction,sulfur disproportionation and iron reduction were changed along the groundwater flow,indicating the occurrence of related metabolic processes.?2?The arsenic,sulphur and iron cycling functional genes and associated microbial community in sediments from the arsenic-contaminated area in the Hetao Basin,China were obtained by metagenomic approaches.The presence of typical sulfur disproportionating genera?Desulfobulbus and Desulfocapsus?demonstared the occurrence of microbe-medicated sulfur disproportionation in the high arsenic sediments.Microbe-mediated sulfate reduction may be an important process regarding co-metabolism of Fe-S-As.?3?The Fe-S-As metabolism pathways depicted by metagenomic analysis on functional genes revealed that the bacterial sulfate reduction,the disproportionation of sulfur and its compounds,and the reduction of Fe?III?oxyhydroxides could promote the release and mobilization of arsenic simultaneously.Our findings indicate the strong association among the biogeochemical cycle of iron,sulfur and arsenic.