Study On The Characteristics And Indicative Microorganisms Of Microbial Community In Chromium Contaminated Soil

With the development of tanning technology and electroplating industry,chromium(Cr)pollution has become one of the main soil heavy metal pollutions in China,which seriously affects the soil ecological environment and human health.In this study,Illumina Mi Seq high-throughput sequencing technology was used to analyze the soil microbial community characteristics under different concentrations of chromium pollution around the sludge heap of a tannery in Hebei Province.The aims of this study are:(i)to explore the microbial community construction mechanism and the main environmental driving factors in affecting the community structure;(ii)to reveal the indicator microorganisms in chromium contaminated soil.The present study further improves our understanding of the characteristics of soil microbial communities under chromium stress.The results show that:(1)The concentrations of total chromium and hexavalent chromium in mild pollution(MIP),moderate pollution(MOP)and high pollution(HIP)contaminated soil samples were significantly different(P<0.05).The content of soil organic matter and p H value were significantly different among the samples(P<0.05).The soil moisture content in moderate pollution(group B)was the lowest among three treatments.(2)In comparison with MIP,the alpha diversity of the soil bacterial community increased in MOP samples,and then decreased in HIP samples.The bacterial community structures between the MOP and HIP samples were significantly different.The deterministic process of bacterial community construction is the main process in Cr pollution samples,and the stochasticity ratio(SR)decreases with the increase of chromium concentration,which is considered as homogeneous selection process.According to the analysis of LEf Se,Sphingobacteriia,Gammaproteobacteria,and Rhodospirillales bacterium are considered as indicator microorganisms for MIP samples;Syntrophic bacterium are considered as indicator microorganisms for MOP samples;Bacilli and Chromatiales bacterium are considered as the indicator microorganisms for HIP samples.(3)The alpha diversity of soil fungal communities increased with the increase of chromium concentration.The fungal community structure changed significantly between MIP and HIP samples.Null model analyses indicated that the construction of fungal community in MIP and MOP samples were dominated by random factors,with the increase of chromium pollution concentration,the fungal community construction process of HIP samples were dominated by deterministic factors.For fungal community,Pleosporales and Eurotiomycetes fungus are considered as indicator microorganisms for MIP samples;Pezizomycetes are considered as indicator microorganisms for MOP samples;Morosphaeriacea,Phaeosphaeriaceae and Orbiliales are considered as indicator microorganisms for HIP samples.The paper has 28 figures,15 tables and 100 references.