Metagenomic analysis exhibited the co-metabolism of polycyclic aromatic hydrocarbons by bacterial community from estuarine sediment

The bacterial community from estuarine sediment undertakes the bioremediation and energy transformation of anthropogenic pollutants especially polycyclic aromatic hydrocarbons (PAHs). However, information and studies on bacterial synergism and related metabolic profiles under the stress of PAHs are limited. In this study, sediments from estuarine were collected and co-incubated with a classical PAH, pyrene. The results showed that Alpha- and Gammaproteobacteria became abundant at the late domesticating phase with the dominant genus of ZD0117, the uncultivated bacteria affiliated into Gammaproteobacteria. Functional gene analysis based on metagenomic sequencing showed that quantitatively changes of genes directly related to the degradation of aromatic hydrocarbon coordinated with genes involved into various metabolic pathways such as acylglycerol degradation, nitrogen fixation, sulfate transport system, Arnon-Buchanan cycle, and Calvin cycle (P < 0.01 and |ρ| > 0.8). Fifty-six metagenome-assembled genomes (MAGs) were reconstructed, which were primarily composed by Alpha- and Gammaproteobacteria. Bacteria belonging to the phylum Proteobacteria were found to be abundant in MAGs and contained genes encoding for dehydrogenase, which are key enzymes for pyrene degradation. In addition, genomes of uncultivated bacteria were successfully reconstructed and were proven to carry genes of synergistically metabolizing pyrene. Based on analysis of typical MAGs, the metabolic pathways involved in syntrophic associations of a pyrene-degrading consortium were reconstructed. The results in this study could make us fully understand the metabolic patterns of pyrene-degrading consortium from the estuarine sediment and widen the scope of functional bacteria.