Isolation and molecular identification of ultraviolent resistant soil bacteria indigenous to south of Iran

Background and Aim : Harmful environmental factors such as high temperature, salinity and high levels of solar radiation are constant challenges for living organisms which inhabit extreme environments like high attitudes, deserts and hot springs. However, there are various microorganisms that they cope with damaging factors and they are adapted to the extreme situations. Enzymes and secondary metabolites that are produce by UVB resistant bacteria can be used in biotechnological and medical industries as anticancer, antioxidants and skincare products.Methods : Eight soil samples were collected from Shiraz and Ahwaz, southern cities of Iran, which are exposure to high solar radiation, to study bacterial resistance to UVB radiation. Soil samples were cultured on the Tryptone Soy Agar and Luria Bertani Agar medium and ۱۰۸ pure colonies with various colors and shapes were in exposure to UVB lamp (Philips/۲۰w) with wavelength of ۳۱۲ nm, from ۳۰ centimeters distance for ۲۰ to ۹۰ minutes. Then to avoid photoreactivation they were wrapped in foils and incubated at ۳۰◦ C. Also, photo reactivation was tested by incubating UVB irradiated colonies under photo-active radiation lamps at ۳۰◦ C. All of experiments were repeated three times.Results : At last four bacteria were highly resistant to UVB radiation which include: ۱. A coccoid, gram positive, catalase and oxidase positive and nonmotile bacterium with orange pigmentation was isolated from a soil sample of Shiraz, ۲. A coccoid, gram positive, catalase and oxidase positive and motile bacterium with orange pigmentation, ۳. A coccoid, gram positive, catalase and oxidase positive and nonmotile bacterium with yellow pigmentation , ۴. A rod shaped, gram positive, spore forming, catalase and oxidase positive and nonmotile bacterium which were isolated from Ahwaz soil samples and they could tolerate ۵۰, ۶۰, ۵۰ and ۷۰ minutes of UVB radiation, respectively.Conclusion : UVB resistant bacteria were isolated from southern cities of Iran. These bacteria may have secondary metabolites that can be used as sunscreen and other skincare products.