Study On The Polyphasic Taxonomy Analysis Of Strain X-121~T And Stress Resistance Regulatory Function Of Mscl From Denicoccus Radiodurans R1

Deinococcusis a genus of bacteria that can adapt to extreme environment.Most of the bacteria in this genus have strong resistance to radiation and other extreme stresses such as high temperature,desiccation,low temperature,oxidizing agents.At the time of writing,more than 60 species placed in this genus with validly published names have been isolated from various environments include soils,foods,faeces,dust,hot springs,Antarctic environments and the plant rhizosphere,etc.Deinococcus radiodurans,the type species of this genus,was best known for its champion extreme radiation resistance.Considering the specificity of Deinococcus.We selected the gene of mechanosensitive channel with large conductance and a novel species as a model to reveal some properties of this genus.First,study was performed on a novel strains,desigated X-121T which was isolated from soil samples collected from Taklimakan desert of Xinjiang,China.Cells of X-121T stain Gram-negative and are gamma-and UV-radiation-tolerant,strictly aerobic,non-motile,short-rod-shaped.It showed the highest 16S rRNA gene sequence similarity with Deinococcus depolymerans TDMA-24T(94.7%).Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain X-121T is member of a novel species belonging to the clade formed by members of the genus Deinococcus in the family Deinococcaceae.The DNA G+C content of strain X-121T was 63.65 mol%.The chemotaxonomic charateristics of strain X-121T were typical of members of the genus Deinococcus,with MK-8 as the predominant respiratory quinone,summed feature 3(16:1?7c,16:1?6c),16:0 and 17:1?8c as major cellular fatty acid,several unidentified phosphoglycolipids and glycolipids as the dominant polar lipid,galactose as the predominant cell-wall sugars and the presence of peptidoglycan with L-ornithine.Strain X-121T is therefore identified as representing a novel species,for which the name Deinococcus taklimakanensis sp.nov.is proposed,with the type strain X-121T(=CCTCC AB 207228T=KCTC 338421).Second,the mscl gene homlog from Escherichia coli K-12 and Deinococcus Radiodurans R1 were recovered by PCR using standard reaction conditions,then subcloned using the pB10d expression construct.The mscl-and mscs-null MJF465-bacterial strain was used to host these expression constructs and then the survival of both host strain and MJF465(mscl-,mscs-)under osmotic downshift,UV radiation and desiccation conditions were analyzed.We found that MJF465-(mscl-,mscs-)is approximately 10-fold more sensitive to osmotic downshift than host strain,but there was no remarkable difference in survival after UV radiation and desiccation for both strain.The result revealed that mscl gene of Deinococcus radiodurans R1 can express normally in MJF465-(mscl-,mscs-)and perform cell osmotic pressure regulating function.