Methanogenic and Aerobic Biodegradation of Model Polycyclic Aromatic Compounds Associated with Canadian Oil Sands

摘要

Polycyclic aromatic compounds (PACs) are ubiquitous molecules that can be of high importance to remediate due to their potential negative health and environmental effects. The present study used Canadian Oil Sands-derived microbial consortia established methanogenically or aerobically and amended with phenanthrene, dibenzothiophene (DBT), or 2,6-dimethylnaphthalene (2,6-diMN) as sole carbon and energy sources under three salinities. Methane formation was statistically higher in PAC-amended treatments relative to unamended controls under brackish conditions. A fumarate addition metabolite was tentatively detected in incubations amended with 2,6-diMN. DBT was degraded with concomitant methane formation, the first report of this metabolism. 16S rRNA gene sequencing revealed the dominance of methanogens and known PACs degraders. Genus Smithella was only detected in DBT-amended incubations in relatively high abundances suggesting its role in DBT degradation anaerobically. Aerobic degradation of PHEN and 2,6-diMN was also observed. Time-course experiments showed faster PHEN degradation under saline conditions and that the microbial communities were dominated by Janibacter sp, which was also isolated. This research shows that microbial communities from bitumen-impacted environments have the natural ability to degrade PACs, with potential applications in bioremediation.