| Summary: | Naphthenic acids (NAs) and high molecular weight polycyclic aromatic hydrocarbons (HMW-PAHs) are both natural components of fossil fuels that cause a number of environmental issues. Using enrichment cultures derived from oil sands-process affected water (05PW), the biodegradation of three HMW-PAHs that differed in number of aromatic rings was investigated. All HMW-PAHs were degraded by up to 75% over 33 days. Bacterial communities were dominated by the genera Pseudomonasl Bacillus and Microbacterium and fungal communities by Cladosporium and Penicllium. Pseudomonas putida KT2440 has previously been shown to transform both NAs and other hydrocarbons and so was selected for co-culture biodegradation experiments with a NA-tolerant culture of Chlorella vulgaris Nr 211/12. Co-cultures demonstrated biodegradation of recalcitrant components of commercial NAs within 14 days and degraded significantly more adamantane-1-carboxylic acid (A1CA) than individual cultures of either P. putida or C. vulgaris within 33 days. Enrichment cultures derived from 05PW were used to further investigate the biodegradation of A1CA and 3EA. Both A1CA and 3EA were significantly degraded after 33 days and mass spectral analysis demonstrated the production of hydroxyadamantane intermediates with a concurrent decrease in toxicity. Comparisons of 165 rRNA gene sequences at days 0 and 33, during biodegradation showed an increase in abundance at day 33 of the genera Pseudomonas, Acidovorax, Flavobacterium and Methylobacterium.
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