Isolation and characterization of naphthalene-degradation bacteria from Qurugol Lake located at Azerbaijan

Abstract

Bacteria have different decomposing enzymes, a feature which makes them outstanding among all other microbes. One of the major methods to reduce various pollutants is applying biologic method which is known as bioremediation. The aim of the present study was tried to analyze the existence of naphthalene-degradation bacteria phenotypically and genotypically in Qurugol Lake, located in East Azerbaijan Province in Iran. For this aim at the end of each rainy season samples were taken from the locations of the lake which were the most polluted. These samples were incubated in r. specific medium where naphthalene was the only carbonic source of energy for providing the poly aromatic hydrocarbons (PAHs) energy. The single colonies were isolated and the primary phonotypic and biochemical tests were carried out. After that, for genotypic analysis, their 16S rRNA genes were separated and sequenced. Considering the fact that the decomposing bacteria of PAHs compounds, which were taken from the lake, were isolated, it became obvious that part of polluting process is done by these bacteria. The significant bacteria in this case are bacillus sp. and closely related type strains include B. pumilus (99.9%) Which are capable of decomposing PAHs efficiently in 5% salt concentrations also Shewanella sp. and closely related type strains include Sh. Xiamenensis (99.1%) which are capable of decomposing PAHs efficiently in 1/5% salt concentration. On the basis of phenotypic and phylogenetic results, it is recommended that isolated RCRI7(=RCRI8) represents a novel strain of the species Sh. xiamenensis and The GenBank/EMBL accession number for the 16S rRNA gene sequences of strain RCRI7 is GO988720. The level of DNA-DNA relatedness between strain RCRI7 and phylogenetically the closest related strain, Shewanella xiamenensis JCM 16212T was 51%.