A PAH-degrading bacterial community enriched with contaminated agricultural soil and its utility for microbial bioremediation

A bacterial community was enriched with polycyclic aromatic hydrocarbons (PAHs) polluted soil to better study PAH degradation by indigenous soil bacteria. The consortium degraded more than 52% of low molecular weight and 35% of high molecular weight (HMW) PAHs during 16 days in a soil leachate medium. 16S rRNA gene high-throughput sequencing and quantitative polymerase chain reaction analyses for alpha subunit genes of ring-hydroxylating-dioxygenase (RHD alpha) suggested that Proteobacteria and Actinobacteria at the phylum level, Pseudomonas, Methylobacillus, Nocardioides, Methylophilaceae, Achromobacter, Pseudoxanthomonas, and Caulobacter at the generic level were involved in PAH degradation and might have the ability to carry RHD alpha genes (nidA and nahAc). The community was selected and collected according to biomass and RHD alpha gene contents, and added back to the PAH-polluted soil. The 16 EPA priority PAHs decreased from 95.23 to 23.41 mg kg(-1) over 35 days. Compared with soil without the introduction of this bacterial community, adding the community with RHD alpha genes significantly decreased soil PAH contents, particularly HMW PAHs. The metabolic rate of PAH5 in soil was positively correlated with nidA and nahAc gene contents. These results indicate that adding an indigenous bacterial consortium containing RHD alpha genes to contaminated soil may be a feasible and environmentally friendly method to clean up PAHs in agricultural soil. (C) 2019 The Authors. Published by Elsevier Ltd.