Potential Changes in Soil Microbial Composition under 1,2-Dichlorobenzene Contamination

Abstract

Chlorine-containing organic compounds are important industrial solvents but are severely toxic to humans and the environment. Because of their stability and dense non-aqueous phase, they barely biodegrade when released into soil and groundwater systems and may significantly impact the soil environment. One bioremediation approach, biostimulation, adds rate-limiting nutrients to the soil to promote biodegradation processes, but the link remains unclear between stimulated microbial communities and nutrient inputs in anaerobic environments. This study evaluated changes to soil microbial communities in 1,2-dichlorobenzene (1,2-DCB)-contaminated soil under diverse carbon (C) and nutrient conditions. The experiments used anaerobic microcosms that were amended with various C and nutrient sources, and the analysis employed real-time PCR and next-generation sequencing. The results reveal that methanogens may have high resistance to 1,2-DCB in oligotrophic conditions. However, bacteria such as Pseudomonas, Sphingomonas, and some uncultured genera in the Xanthomonadaceae, Pseudomonadaceae, and Bacillales families can resist high 1,2-DCB concentrations when N and P sources are available. These results indicate that external N and P sources are important for stabilizing soil microbial communities and their processes in contaminant sites.