Taxonomic Identification And Genomic Characterization Of A New Species Of The Genus Ruania

During the investigation of cultivated bacterial diversity in saline-alkaline soil in China,a Gram-stain-positive,strictly aerobic,ivory-colored,rod-shaped bacterial strain,designated RN3S43^T,was isolated from saline-alkaline soil,in Tumd Right Banner,Inner Mongolia,China.In this study,a polyphasic taxonomic identification method was used to characterize the strain.The main conclusions are as followed:（1）The cells of strain RN3S43^T were positive to oxidase,catalase,urease,and nitrate reductase.The methyl red and Voges-Proskauer tests were negative.The phylogenetic trees based on the 16S r RNA gene sequences and the whole genome both showed that strain RN3S43^T tightly clustered with Ruania alba YIM93306^T,and shared 95.5%and<95.0%of 16S r RNA gene similarities with R.alba YIM 93306^T and all the other type strains.MK-8 was the major respiratory quinone.Diphosphatidylglycerol,phosphatidylglycerol,phosphatidylinositol,and an unidentified lipid were the major polar lipids.The major fatty acids were anteiso-C_15:0 and iso-C_15:0.The results of phylogenetic,physiological,and phenotypic tests allowed the discrimination of strain from its phylogenetic relatives.Ruania alkalisoli sp.nov.is therefore proposed,and the type strain is RN3S43^T（=CGMCC 1.18652^T=KCTC 49471^T）.（2）The genome analysis showed that strain RN3S43^T had 3543 gene clusters,while the strains R.alba YIM 93306^T,R.albidiflava 3-6^T,R.rhizosphareae LNNU 22110^T and R.zhangjianzhongii HY168^T had 3424,3142,3483,and 3469 gene clusters,respectively.The pan-genomes of these five Ruania strains had 4677 clusters,of which the core genome had 2045 clusters,accounting for 43.7%of all clusters.Molecular function and cellular component fractions were compared,and GO analysis revealed that biological processes accounted for the highest proportion（53%）of the entire core genome cluster.The main Gene Ontology（GO）analysis showed that the main molecular functions included hydrolase activity（14.8%）,molecular function（14.3%）,and peptidase activity（11.3%）,while cellular components mainly included cellular parts（44.8%）,membrane（42.5%）and cellular components（5.7%）.To better adapt to the extreme environment such as a saline-alkaline environment,the active H₂O₂ in the cell can be rapidly converted into stable oxygen and H₂O,to reduce the accumulation of reactive oxygen species and improve the survival of the strain inthe saline-alkaline soil.The genome of strain RN3S43^T harbored genes involving the synthesis of tetrahydropyrimidine,glutamic acid and trehalose,indicating that the strain RN3S43^T could maintained the Osmotic equilibrium by synthesizing organic solutes.Strain RN3S43^T contains genes encoding the regulation of glycine betaine transport,by which the strain can absorb glycine betaine from the outside to maintain intracellular high osmotic pressure to adapt to extracellular high salt or salt stress environment.