A bacterial strain, designated S9-5T, was isolated from moraine samples collected from the north slope of Mount Everest at an altitude of 5 500 m above sea level. A polyphasic study confirmed the affiliation of the strain with the genus Sphingomonas . Strain S9-5T was an aerobic, Gram-stain-negative, non-spore-forming, non-motile and rod-shaped bacterium that could grow at 10–40 °C, pH 5–8 and with 0–9 % (w/v) NaCl. Q-10 was its predominant respiratory menaquinone. Diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, an unidentified phospholipid, an unidentified aminophospholipid and eight unidentified lipids comprised the polar lipids of strain S9-5T. Its major fatty acids were summed feature 8 (C18 : 1  ω7c and/or C18 : 1  ω6c) and C16 : 0. The G+C content was 65.75mol%. Phylogenetic analysis based on 16S rRNA sequences showed that strain S9-5T was phylogenetically closely related to Sphingomonas panaciterrae DCY91T (98.17 %), Sphingomonas olei K-1-16T (98.11 %) and Sphingomonas mucosissima DSM 17494T (97.39 %). The average nucleotide identity values among strain S9-5T and Sphingomonas panaciterrae DCY91T, Sphingomonas olei K-1-16T and Sphingomonas mucosissima DSM 17494T were 78.82, 78.87 and 78.29 %, respectively. Based on the morphological, physiological and chemotaxonomic data, strain S9-5T (=JCM 34750T=GDMCC 1.2714T) should represent a novel species of the genus Sphingomonas , for which we propose the name Sphingomonas radiodurans sp. nov.

The Hexi Corridor is an arid region in northwestern China, where hypoliths are widely distributed, resulting from large amounts of translucent stone pavements. In this region, the water and heat distributions are uneven, with a descent gradient from east to west, which can affect the area’s biological composition. The impact of environmental heterogeneity on the distribution of hypolithic microbial communities in this area is poorly understood, and this is an ideal location to investigate the factors that may influence the composition and structure of hypolithic microbial communities. An investigation of different sites with differences in precipitation between east and west revealed that the colonization rate decreased from 91.8% to 17.5% in the hypolithic community. Environmental heterogeneity influenced both the structure and function of the hypolithic community, especially total nitrogen (TN) and soil organic carbon (SOC). However, the effect on taxonomic composition was greater than that on ecological function. The dominant bacterial phyla in all sample sites were Cyanobacteria, Actinobacteria, Proteobacteria, and Deinococcus-Thermus, but the abundances varied significantly between the sampling sites. The eastern site had the highest relative abundance of Proteobacteria (18.43%) and Bacteroidetes (6.32%), while the western site had a higher relative abundance in the phyla Cyanobacteria (62%) and Firmicutes (1.45%); the middle site had a higher relative abundance of Chloroflexi (8.02%) and Gemmatimonadetes (1.87%). The dominant phylum in the fungal community is Ascomycota. Pearson correlation analysis showed that the soil’s physicochemical properties were also associated with changes in community diversity at the sample sites. These results have important implications for better understanding the community assembly and ecological adaptations of hypolithic microorganisms.