Reyhaneh Shekari - Department of Microbiology, Faculty of Biological Sciences, Alzahra University, Tehran, Iran
Parisa Mohammadi - Department of Microbiology, Faculty of Biological Sciences, Alzahra University, Tehran, Iran Research Center for Applied Microbiology and Microbial Biotechnology, Alzahra University, Tehran, Iran
Gholamreza Zarrini - Department of Animal Biology, Faculty of natural sciences University of Tabriz, Tabriz, Iran

BACKGROUND AND OBJECTIVESGroundwater contamination with benzene, toluene, ethylbenzene, and xylene (BTEX) has very risk in environment and health, and requiring the urgent development of methodologies to remove these compounds. The aim of this study was to isolate an efficient strain capable of biodegrading these compounds.MATERIALS AND METHODSSampling was done from a depth of ۵۰ cm in oil-contaminated areas. First, the soil sample was enriched with ۱% BTEX for ۱۴ days. Next, this suspension was cultured on solid medium and its microorganisms were purified. Then, bacteria were cultured in the presence of ۱% BTEX. After that, evaluation of the biodegradation of BTEX was done by Gas chromatography-mass spectrometry. Finally, Molecular identification of the isolate was done with a ۱۶s rRNA gene primers.RESULTS AND DISCUSSIONThe selected bacterium had the ability to grow at temperatures of ۲۰ to ۴۰ degrees in pH ۵ to ۹ and sodium chloride concentrations of ۰ to ۸%. The GC-MS results showed that this bacterium could reduce benzene by ۶۳%, toluene by ۵۷%, ethylbenzene by ۹۳% and xylene by ۱۰۰% in the aqueous phase. Molecular identification of the isolate showed that this strain is ۹۸% similar to Stutzerimonas balearica. This strain has a great ability to remove xylene (both ortho and para) and ethylbenzene, although it has less ability to remove benzene and toluene.CONCLUSIONBTEX compounds are very toxic and carcinogenic. This strain can be a proper option for bioremediation due to no produce by-products.

Oil pollutant, Remediation, Molecular identification, GC-MS