More functional genes and convergent overall functional patterns detected by GEOCHIP in phenanthrene-spiked soils.

To explore the effect of phenanthrene on the functional diversity of soil microbial communities, Luvisol and Cambisol spiked with phenanthrene and their corresponding control soils were incubated in soil microcosms. Total community DNA extracted from samples taken at days 0 and 21 was analyzed by geochip. The number of genes detected by geochip was unexpectedly higher in spiked soils than in control soils, especially for Luvisol. Enriched genes in the spiked Luvisol were mainly affiliated to proteobacterial and actinobacterial genes involved in the degradation of aromatic compounds, heavy metal resistance, sulfate reduction, nitrogen and carbon cycling, suggesting changes in the relative abundance of these aerobic and anaerobic functional groups after phenanthrene spiking. Interestingly, the overall functional gene patterns in the different soils converged after phenanthrene spiking, indicating the selection of similar functional groups.