Abstract
Polyaromatic hydrocarbons (PAHs) are uncharged, non-polar molecules generated from natural and anthropogenic activities, where the emissions from anthropogenic activities predominate. Chrysene is a high molecular weight PAH, which is found to be highly recalcitrant and mutagenic in nature. The aim of this study was to isolate chrysene-degrading microorganisms from oil-contaminated water and to enhance their degradative conditions using design expert. From the various samples collected, 19 bacterial strains were obtained through enrichment culture and the one which showed highest activity was identified by 16S rRNA sequencing as Bacillus halotolerans. Under optimum conditions of 100 mg/L chrysene concentration, 1,000 mg/L nitrogen source, and pH 6, B. halotolerans exhibited 90% chrysene degradation on sixth day. Positive results for the enzymes laccase and catechol 1,2 dioxygenase confirmed the ability for chrysene degradation by the isolated strain. Major metabolic intermediate determined in gas chromatography-mass spectrometry (GCMS) analysis was diisooctyl phthalate. Hence it can be concluded that B. halotolerans can be a promising candidate for the removal of high molecular weight (HMW) hydrocarbons from contaminated environments.
Highlights
Polyaromatic hydrocarbons (PAHs) are non-polar lipophilic organic compounds present in the atmosphere as a result of incomplete combustion of automotive waste, organic matter, refineries, power plants, tobacco smoke, forest fires and smoked foods (Samanta et al 2002)
The objective of the study was to segregate a bacterial strain that had the ability to develop in pure culture with chrysene as a sole carbon source and to characterize the intermediates by chromatographic method
The one which showed a good growth profile was selected as the best chrysene degrader and named as S10 (Figure 1)
Summary
Polyaromatic hydrocarbons (PAHs) are non-polar lipophilic organic compounds present in the atmosphere as a result of incomplete combustion of automotive waste, organic matter, refineries, power plants, tobacco smoke, forest fires and smoked foods (Samanta et al 2002). Due to their cytotoxic, mutagenic, and carcinogenic effects, PAHs are classified as dangerous compounds. According to the United States Environmental Protection Agency (USEPA), 16 PAHs are priority pollutants out of which eight are typically considered probable cancer-causing agents This includes benzo[A]-fluoranthene, benzo[h]fluoranthene, benzo[a]anthracene, dibenzo [a,h]anthracene, benzo[a]pyrene, benzo[g,h,i]-perylene, indenol [1,2,3,c-d] pyrene and chrysene (Tam et al 2003)
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