Dibenzothiophene (DBT) is a sulfur-containing PAH typically used as a model chemical to study biodegradation of PAHs and bioremediation. The effects of using different carbon sources (sodium gluconate, glucose, sodium pyruvate, sodium acetate and glycerol) as a co-substrates were investigated during DBT biodegradation by Paraburkgolderia sp. C3. This is the first study showing a direct association between RLs biosynthesis and DBT biodegradation induced by different carbon sources in Paraburkgolderia species. Glycerol and pyruvate significantly enhanced DBT biodegradation after 7 days, while glucose inhibited DBT biodegradation. Glycerol can induce C3 produce at least five RLs by HPLC separation and MALDI-TOF/TOF identification. The rhamnolipid precursor produced by this strain is mainly derived from the fatty acid synthesis (FAS II) and β-oxidation pathway. The genome showed two (FabF and FabG) and four (FadA, FadE, FadB and EchA) genes involved in FAS II and β-oxidation, respectively. The genome also carried the rhlA and rhlB genes involved in rhamnosyltransferase for RL biosynthesis and two DBT dioxygenase genes (nahAc and catA). The findings suggest a viable approach of using the biodiesel byproduct glycerol to remediate PAH-contaminated environments. In future, we plan to knock out genes in the fatty acid synthesis (FAS II) and β-oxidation pathways, which will further determine the reason why glycerol promotes DBT degradation. In addition, using recombinant DNA and genetic engineering techniques in microbial breeding, it is expected to construct a large number of highly efficient engineered bacteria with enhanced pollutant degradation ability to speed up the process of environmental governance.

Genome, metabolic pathways and characteristics of cometabolism of dibenzothiophene and the biodiesel byproduct glycerol in Paraburkholderia sp. C3

ACS Fall 2021

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