Sunday, July 26, 2009
P65

Biodegradation of polycyclic aromatic hydrocarbons by Arthrobacter oxydans isolated from oil refinery wastes

Elisabeth Koch1, Sukhdeep Sidhu1, Marc Habash1, Les Stehmeier2, Hung Lee1, and Jack T. Trevors1. (1) Environmental Biology, University of Guelph, 50 Stone Road East, Guelph, ON N1G 4W1, Canada, (2) Environment and Corrosion, NOVA Chemicals Research and Technology Centre (NRTC), 2928 16 ST NE, Calgary, AB T2E 7K7, Canada

The objective of this research was to isolate polycyclic aromatic hydrocarbon (PAH) degrading microorganisms from refinery landfarm soil for use to degrade PAHs in petroleum refining wastes.  Microbial enrichment experiments using soil and root rhizosphere samples obtained from a NOVA Chemicals landfarm site in Sarnia, Ontario were carried out using shake flask experiments.  Several PAH-degrading microorganisms present in the landfarm soil samples were isolated and identified using culture based methods with phenanthrene as the sole carbon source.  The two best phenanthrene degraders were identified as Arthrobacter oxydans and Serratia proteamaculans by partial 16S rRNA sequence analysis. The ability of Arthrobacter oxydans to degrade individual and mixtures of PAHs at different concentrations was investigated.  Using high bacterial cell densities (108 cells/mL), 200 mg/L of phenanthrene was completely degraded by Arthrobacter oxydans in 24 hours.  In experiments using pairs of hydrocarbons including 200 mg/L phenanthrene and 50 mg/L of either anthracene, pyrene, chrysene or benzo(a)pyrene, phenanthrene was completely degraded within 24 hours.  Anthracene was completely degraded within 4 days, while 49% of pyrene and 30% each of chrysene and benzo(a)pyrene were biodegraded within 9 days by Arthrobacter oxydans.  Studies are underway to examine the degradation of a greater number of PAH mixtures and also the ability of Arthrobacter oxydans to degrade the PAHs in refining effluents from NOVA Chemicals. 

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