Effects of trichloroethylene stress on the microbiological characteristics of Mollisol

Trichloroethylene (TCE), one of 129 kinds of priority pollutants, is the most common halogenated organic pollutant in the environment. To explore the changes in soil physicochemical properties and biological activities then clarify the effects of these factors on bacterial, fungal and actinomycetes communities in Mollisol under TCE stress is the significance of our research. The results indicated that when TCE concentration was greater than 10 mg kg^-1, soil quality declined and soil decomposition of organic matter and cycling of mineral nutrients were inhibited through an effect on soil microbial biomass. Operational taxonomic units (OTUs) richness of the bacteria in Mollisol was altered by TCE contamination. The S_Chao1 and H_Shannon indices of bacterial communities in Mollisol decreased when 40 mg kg^-1 TCE was applied. Meanwhile, the OTU richness of fungi in Mollisol was altered by TCE contamination. The H_Shannon indices of the fungal communities in Mollisol were inhibited by higher TCE concentrations (20 and 40 mg kg^-1 TCE). TCE altered the content of some bacteria, fungi and actinomycetes involved in soil carbon and nitrogen cycling and metabolism, such as Acidobacteria, Proteobacteria, Planctomycetes, Chytridiomycota, Streptomycetales, Pseudonocardiales, Propionibacteriales and Rhizobiales, and thus influenced nutrient cycling and the process of energy metabolism in Mollisol. In addition, redundancy analysis (RDA) results indicated that physicochemical properties and biological activities under TCE contamination significantly affected soil microbial community composition thus confirming that TCE interfered with the carbon and nitrogen cycling and metabolism of soil microorganisms. The results of this study are of great importance for revealing the effects of TCE stress on the microbiological characteristics of Mollisol, and also provide more useful information for determining the potential ecological risk of organic pollutants in Mollisol.