Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental contaminants that are hazardous to human health. It has been demonstrated that members of the Mycobacterium genus are among the most effective degraders of PAHs, but few studies have focused on the degradation of PAH mixtures. In this study, 3 isolates (named czh-3, czh-101, czh-117) of phylogenetically distinct Mycobacterium species were chosen to investigate single and mixed PAHs metabolism. The mixture of pyrene and phenanthrene, resulted in antagonized degradation by bacterial species czh-3 and czh-101, correlated with reduced bacterial growth, while no antagonism and bacterial growth inhibition were observed in czh-117. Relying on the investigation of PAHs’ metabolite pathways, in two of three strains (czh-3 and czh-101) that exhibited antagonized mixture degradation, metabolites were identified that belonged to a pathway not normally used by the organism in the degradation of single PHE, conversely, strain czh-117 showed little change between mixed- and single-PAH metabolic profiles. The hypothesis of the antagonistic mechanism exhibited in czh-3 znd czh-101 was that PHE degrade through the dioxygenation pathway and generate phenanthrene-diol, which auto oxidize into toxic phenanthrene-dione and result in the reduced bacterial growth. To verify the hypothesis, phenanthrene-dione was detected in the culture during the degradation of mixed PAHs, and then we will investigate the correlation between phenanthrene-dione’s concentration and bacterial growth inhibition. Besides, the complete genome sequencing of 3 organisms were accomplished, the following research is to see whether these 3 bacterial species possess genes to encode quinone reductase enzymes, which translate quinone into non-toxic phenanthrene-diol.<br/> <br/>

Determine mechanistic causes for antagonism in PAH mixture degradation in mycobacterium species

2019 Spring National Meeting

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