Isolation and phenotypic, genotypic characterization of arsenic resistant bacteria from Urmia lake

Extensive arsenic contamination of groundwater, rivers and agricultural farms has led to widespread arsenic poisoning and consequent problems associated with health and economy. Millions of people worldwide are threatened by arsenic contamination thus serious actions should be taken to prevent likely global calamity. In recent years many studies have been performed to understand bacterial arsenic detoxification and metobolism which paved the way for bioremediation applications. This thesis study attempted to isolate and characterize arsenic resistant bacteria from drying Urmia lake. LB medium containing 10mM arsenate and %7.5 NaCl adjusted at pH 9.5 was used for initial isolation. Identification of bacteria was carried out based on phenotypic and genotypic studies and ten isolates were selected. 16s rDNA analysis revealed that all strains were mainly belonged to Bacillus genus. For some of the strains, maximum tolerance concentration for either arsenate and arsenite was considerably high, 320mM and 32mM respectively. All of the strains harboured arsenate reductase gene (arsC). The arsB gene was identified in all strains except Bacillus sp. strains S1, S8, S12 and E15. The metabolic genes of respiratory arsenate reductase (arrB) and arsenite oxidase (arxA) were identified in none of isolates. This study could be remarkable of it's kind in Urmia lake because it is relatively the first study which has been done in Urmia lake. Current study could provide data for studies conducting bioremediation applications in order to prevent arsenic disaster in vicinal territories.