Detection of plasmids in arsenic (As) resistant bacteria isolated from As- contaminated groundwater Minima Rain and Pink Sara* Department of Biotechnology, Indian Institute of Technology, Khartoum, West Bengal-721302, India [email protected] Com, Ph: +91 8348523016 Abstract Role of plasmids in conferring resistance to several heavy metals and antibiotics to naturally occurring bacteria is well known. In contaminated environments, presence of metal resistant genes on plasmids often provide the other bacteria within the name niche to acquire the necessary genes at times of severe (metal) stress.
Several arsenic (As) resistant bacterial strains were isolated from contaminated groundwater samples collected from Chad and Barajas districts of West Bengal and Gorham district of Assam. All the isolated bacteria were identified by ASS RNA gene sequencing. The phylogeny analysis of the strains using ASS radar sequence revealed strains to be under the genus Cacciatore, Counteracted, Rhizome, Interacted and Orthodontics. Isolated bacteria were tested for the presence of lassies using the modified alkaline lists method.
The study revealed that the frequency of the occurrence of plasmids in arsenic resistant bacteria was more than that in the common bacteria. In the present study, fifty seven As resistant bacterial isolates were screened for presence of plasmids within and twenty nine of them were found positive. The size of the plasmid Dana were between 4 to 11 KGB. All the plasmid bearing isolates showed elevated tolerance towards arsenate and arsenate (MAT 400 mm and 20 mm respectively) while tolerance to other heavy metals like
Cue+, CDC+, Cry+ and Pub+ (MAT < 3 mm) was moderate. Plasmid bearing isolates were tested for their resistance against five antibiotics, out of which all except one were found to be resistant against inclining. Plasmid curing was successfully carried out with Debt for few isolates. Compared to wild cured strains showed sensitivity towards inclining and arsenic, suggesting the possible role of plasmids in conferring arsenic resistance. This result was supported by the PC amplification of cytoplasm arsenate oxides (kabob) gene involved in arsenic resistance.