Biodegradation of Petroleum Hydrocarbons by Halophilic and Halotolerant Microorganisms

Abstract

Halophilic and halotolerant organisms can degrade pollutants, although little is known of their capacity to degrade benzene, toluene, ethylbenzene, and xylenes (BTEX). These compounds are of concern because they are stable, highly water soluble, and benzene is a known carcinogen. Hypersaline soils from oil production sites and naturally hypersaline soils in Oklahoma were assessed for BTEX degradation by native organisms. BTEX degradation was found in the hypersaline soils tested. Highly enriched aerobic cultures were developed from oil brine soil and pristine hypersaline soil that degraded BTEX as the sole carbon and energy source. Enrichments completely mineralized 14^C-benzene to 14^CO2. A halophile was isolated from an enrichment that degraded benzene as sole carbon and energy source in the presence of 1 to 3 M NaCl. 16S rDNA analysis showed > 95 % sequence similarity of the isolate to Arhodomonas aquaeolei and is tentatively referred to as Arhodomonas sp. strain Seminole.