Isolation and Screening of benzene degrading bacteria from Zarand coke making and Tar refinery company

Aromatic hydrocarbons are common pollutants associ ated with petroleum products release. Among these, benzene is one of the most important concerns due to its toxic and carcinogenic potential. Since microorgan isms are able to use aromatic hydrocarbons as a carbon and energy source, they can be used for bioremediation applications. The objective of this research was to isolate and char acterize benzene-degrading bacteria from soil and sewage of Zarand coke making and Tar Refinery Company and to investigate theirs ability in benzene removal. To isolate benzene degrading bacteria, soil and sewage samples were added to benzene-containing minimal salts media. Initially, 12 bacterial isolates were isolated from samples. The four isolates were screened based on high level of benzene resistance. These isolate were identified by morphological features, biochemical tests, and 16S rRNA gene sequencing analysis. Sequence analysis of 16S rRNA showed that the isolated strains were closely related to Pseudomonas putida BSH-1, Pseudomonas stutzeri BSH-3, Pseudomonas xanthomarina BSH-2 and Bacillus sp. The growth rates of the isolates were assessed by a turbidity measurement as optical density at 600 nm in a UV–visible spectrophotometer. The benzene removal assay was performed by reading the optical density of the benzene against a blank at 255 nm wavelength. The results of this study showed that these isolated strains could be considered for the benzene bioremediation.

Keywords:

Benzene , degrading bacteria , coke making , molecular identification , Zarand