Sphingomonas radiodurans sp. nov., a novel radiation-resistant bacterium isolated from the north slope of Mount Everest

Abstract

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.

Genomic Insights into the Radiation-Resistant Capability of Sphingomonas qomolangmaensis S5-59T and Sphingomonas glaciei S8-45T, Two Novel Bacteria from the North Slope of Mount Everest

“…The assay of radiation-resistant ability was detected using ionizing (γ-rays) and non-ionizing (UVC) radiation [ 11 ]. The strains S5-59 T , S8-45 T , and reference type strains were inoculated into 100 mL R2A liquid media, shaken at 200 rpm, cultured at 30 °C for 72 h, and the cell suspensions were then collected.…”

“…As we all know, the high-altitude Mount Everest in the Tibetan Plateau region of China has currently been receiving a large amount of solar radiation—and the higher the altitude, the more cosmic rays it receives [ 3 , 10 ]. Previous studies have reported that a large number of bacteria with radiation resistance live in the moraine soils of the glacier at high altitudes; further, they also have strong antioxidant and cold resistance functions, as well as other functions to cope with the extreme conditions [ 8 , 11 , 12 ]. However, there are fewer reports of novel functional extremophiles in the less-interfered regions of humans and in the higher altitude of the northern slopes of the Mount Everest region, especially on radiation-resistant microorganisms.…”

“…Up to now, 171 species of the genus Sphingomonas have been recognized with validated, published names ( accessed on 12 February 2022). According to previous research by others, species of the genus Sphingomonas can be found distributed throughout ecological niches of extreme environments, such as the soil of subterranean sediment [ 27 ], desert [ 28 ], glacier ice [ 29 ], moraine [ 11 ], etc. Sajjad et al systematically reported the important role of the Sphingomonas species in polycyclic aromatic hydrocarbon (PAH) degradation, plant growth promotion, stress tolerance, and in many other important traits [ 30 ].…”

“…However, limited studies are available on the Sphingomonas species’ associated radiation resistance. Although some studies have reported novel Sphingomonas species’ radiation resistance [ 11 , 31 ], the genomic insight on radiation resistance mechanisms in Sphingomonas has rarely been discussed. Here, we reported two novel radiation-resistant species, S. qomolangmaensis S5-59 T and S. glaciei S8-45 T , isolated from the high altitude of 5700m a.s.l.…”

Paracoccus everestensis sp. nov., a novel bacterium with great antioxidant capacity isolated from the north slope of Mount Everest

“…After being cultured on an R2A agar medium for 5 days, the size and morphology of the cells of strain S8-55 T were determined by electron microscope (JSM-5600, jeol ). When preparing the samples for the scanning electron microscope, cells of strain S8-55 T were fixed on 4 % glutaraldehyde for 8 h. Then the cells were dehydrated in ethanol series with concentrations of 30, 50, 70 and 100 % [46]. After being cultured on an R2A agar medium for 5 days, the colour of colonies of strain S8-55 T was observed.…”