Isolation of Two Radiation Resistant and Desiccation Tolerant Bacteria, Modestobacter sp. A2 and Maritalea sp. B9, from Gandom Beryan Hill in the Lut Desert of Iran

Although dryland ecosystems are the most abundant terrestrial biomes on the Earth, relatively little is known about their microbial diversity and potential metabolic activities. Therefore, the bacterial diversity of the Lut Desert in Iran has been remained largely obscure. In this study, ionizing radiation resistant bacteria from arid Gandom Beryan region was investigated by a culture-dependent method. After exposing the soil and surface sand samples to different periods of dehydration in a desiccator containing silica gel, two nonendospore- forming bacterial isolates were recovered by plating on R2A and TSA agar media and then subjected to a desiccation and ionizing radiation resistance assay. The isolates A2 and B9 were still recovered after 8 weeks in a desiccator containing silica gel and were moderately resistant to gamma radiation with a D10 value between 2 and 4 kGy. Strains A2 and B9 were affiliated with Modestobacter muralis MDVD1T (99.7% similarity) and Maritalea mobilis E6T (97.3% similarity) respectively, using 16S rRNA gene sequence analysis. This is the first report of radiation resistant bacteria which belongs to the genus Maritalea.