Isolation and characterization of a new gamma and UV radiation resistant bacterium from soil samples of an iranian radioactive site and analysis of its pigment

摘要

Radiation resistance has been detected dispersedly among bacteria and some microorganisms growing in natural radioactive environments. Herein, we provide data of isolation and characterization of a new radiation resistant bacterium from a radioactive site in Mashhad, Iran. The soil samples were collected and serial dilution plating was performed in TGY agar. All distinct colonies were isolated and irradiated by gamma radiation. The radioresistant bacterium was characterized by its morphology, biochemistry properties and 16S rRNA gene sequencing. In addition, pigment of the isolate was analysed by spectroscopic properties and LC-MS system and its antioxidant activity was measured by DPPH activity. Among 20 pure colonies, a new gamma and ultraviolet violet radiation resistant bacterium was designated as F3 strain. The isolated bacterium was coccoid in shape, nonmotile, non-sporulating, aerobic and with yellow pigmentation. Phylogenetic analysis based on 16S rRNA gene sequencing revealed that the strain related most closely to Micrococcus lylae. The results of spectroscopic and LC-MS analysis of the pigment show that it was belonged to Astaxanthin. Moreover, the isolate was resistant to gamma radiation (15 kGy) and UV light (400 j m(-2)). The isolate is the first report on radioresistant bacteria belonged to the Micrococcus genus isolated from radioactive region. Due to its antioxidant activity, pigment production and radiation resistant properties, we supposed that this isolate could be a candidate in industrial and bioremediation applications.