Metagenomics Research on PAHs degradation of Lower Reach of the River in Chaohu, China

Abstract

Metagenomics is a powerful tool for investigating functional microorganisms, molecular mechanisms and genes involved in Polycyclic Aromatic Hydrocarbons (PAHs) degradation in in-situ complex environments. In this study, we selected three land use types in the lower reaches of the Shiwuli River of Chaohu and applied metagenomics technology. The results revealed that Rhodoplanes and Bradyhyrhizobium were abundant PAHs degrading microorganisms in the three land use types. Based on the functional annotation and the PAHs pathway, the in situ the microbial communities of the three land use types shared common metabolic pathways for Phenanthrene degradation. In addition, a unique metabolic pathway for PAHs degradation in the agricultural land was identified. Only Patulibacter contributed to flnE (KO14604) in the agricultural land, which was involved in the metabolic pathway of Fluorene degradation. The results of this study suggest that the in situ degradation of PAHs may not be completed by a single genus and it involves the synergy effect of different PAH-degrading microorganisms. There was no significant difference in the compositions and relative abundances of PAH-degrading microorganisms and Kyoto Encyclopedia of Genes and Genomes Orthology (KO) related to PAHs degradation among the three land use types. However, the same microorganism contributed different functional genes in different samples. The genes encoding protocatechuic acid 4,5-dioxygenase were widely distributed and relatively abundant. Therefore, this gene may also be an indicator gene of the PAHs degradation potential. Among all of the factors, the total organic carbon and nitrate nitrogen contents had important influences on the functional genes (KO) related to PAHs degradation (p < 0.05).