Denitrification co-metabolism of PAHs

Co-metabolism refers to the process by which microorganisms degrade organic compounds in the same medium after obtaining most or all of the carbon sources and energy from other substrates. This pathway can effectively promote the microbial degradation of complex organic pollutants and is considered a feasible strategy to effectively remove refractory organic pollutants in the environment [95]. At present, the cometabolic effect of PAHs has also been demonstrated in some aerobic pure culture experiments, such as Dean-Ross et al found that pyrene and anthracene can improve the degradation of fluoranthene by two bacterial strains obtained from contaminated sediment. The functional fusion strain F14 also has a higher rate of pyrene degradation with naphthalene or phenanthrene as cometabolic substrates. The possible mechanism is that the structure of different PAHs and the similarity of the structure of their intermediate metabolites make them have similar metabolic pathways and degrading enzymes; Therefore, the addition of LMW-PAHs that are easily degraded by microorganisms can promote the removal of refractory HMW-PAHs. However, anaerobic co-metabolism of PAHs in complex soil environments is still rare. In this study, typical low molecular weight PAH-phenanthrene and high molecular weight PAH-benzopyrene were used as the matrix of the co-metabolic system, and the anaerobic soil culture experiment with denitrifying electron acceptor (nitrate) was used to investigate the co-metabolism effect of the above PAHs. At the same time, combined with Illumina Miseq sequencing, the microbial mechanism of denitrification co-metabolism of PAHs was explored. This paper aims to provide useful reference information for anaerobic cometabolism remediation of complex PAHs in soil, and lay a foundation for further in-depth revelation of the cometabolism mechanism of soil PAHs.