Isolation of Rhodococcus sp. CMGCZ Capable to Degrade High Concentration of Fluoranthene

Abstract

A bacterial strain CMGCZ was isolated from an abandoned oil field soil sample and identified as Rhodococcus sp. by 16S rRNA sequencing. Rhodococcus sp. CMGCZ was investigated for the degradation of model polycyclic aromatic hydrocarbons (PAHs) and Iranian light crude oil (ILCO) as a sole carbon source in minimal medium. Biodegradation enhancement was attained by supplementing the minimal medium with yeast extract (YE). Rhodococcus sp. CMGCZ was capable to degrade 13.2 % naphthalene (Nap), 13.1 % phenanthrene (Phe), and 99.3 % fluoranthene (Fla) in 1 week and 11 % aliphatic fraction of ILCO in 2 weeks as a sole carbon and energy source. Effect of YE supplementation on degradation potential of Rhodococcus sp. CMGCZ depended upon the added hydrocarbon in the medium. YE completely inhibited Nap degradation, slightly enhanced degradation of Phe (14.8 %) and ILCO aliphatics (13.2 %), and promoted a more rapid degradation of Fla (100 %). YE addition promoted rapid degradation of Fla and eliminated delay of 24 h in Fla degradation that was observed in minimal medium. Rhodococcus sp. CMGCZ was capable to degrade high concentrations of Fla (1000 mg l−1). Rieske [Fe2-S2] center was amplified in Rhodococcus sp. CMGCZ that exhibited homology with Rieske [Fe2-S2] domain protein of Mycobacterium species and pahAC gene of uncultured bacterium clones.