Depth-resolved microbial diversity and functional profiles of trichloroethylene-contaminated soils for Biolog EcoPlate-based biostimulation strategy

This study explores the toxic effect of TCE at different depths of sub-surface soil and underpins microbial community-level suitable carbon (C)-sources that provided directionality to the in situ biostimulation effort via augmentation strategy for effective TCE remediation in soil. The impacts on resident microbial communities and their functional profiles that govern the TCE biodegradation process were identified. Highly contaminated PW01 soil (9 m depth) had severely limited microbial diversity and was enriched in Proteobacteria and Firmicutes. The abundance of TCE degradation-associated genera was observed in all contaminated samples, and the abundance of TCE-degradation-related taxa were positively correlated with soil TCE contamination levels. Community-level metabolic activity associated with the utilization of diverse external C-sources was directly influenced by TCE concentration and soil depth. Multivariate data analysis revealed that the functional genus, TCE concentration, and selected available C substrate uptake capacity correlated in soil samples. Pearson's correlation tests revealed that C sources such as L-arginine, phenylethylamine and γ-hydroxybutyric acid utilization trait exhibited significant positive correlations with chloroalkane and chloroalkene degradation pathway abundance. Ultimately, depth and TCE contamination level-associated soil microbiota and their most preferred C-source understanding could add to facilitate effective biostimulation via external nutrient amendment for efficient in situ TCE degradation.