Abstract
A haloalkaliphilic hydrolytic actinobacterium, strain ACPA22(T), was enriched and isolated in pure culture from saline alkaline soil (soda solonchak) in northeastern Mongolia. The isolate was facultatively alkaliphilic, growing at pH 6.5-10.5 (optimum at 7.3-9.0) and highly salt-tolerant, tolerating up to 3 M total Na(+) as carbonates. The hydrolytic nature of ACPA22(T) was confirmed by two different growth-dependent methods and by the presence of multiple glycosidase-encoding genes in the genome. The 16S rRNA gene-based phylogenetic analysis demonstrated that strain ACPA22(T) formed a deep-branching lineage within the family Glycomycetaceae, with the highest sequence similarity value to Glycomyces buryatensis 18(T) (92.1 %) and Salininema proteolyticum Miq-4(T) (91.8 %). The average amino acid identity values (56.1-61.5 %) between ACPA22(T) and other Glycomycetaceae members with available genomes did not exceed the threshold reported for different genera. The cell wall of ACPA22(T) contained meso-diaminopimelic acid, glycine, glutamic acid and alanine in a molar ratio, characteristic of the peptidoglycan type A1γ'. The whole-cell sugars included mannose, galactose, arabinose, ribose and xylose. The major menaquinones were MK-10(Н(4)) and MK-11(Н(4)). The identified polar lipids were represented by phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and phosphatidylinositol mannosides. In addition, the strain had a few unidentified characteristic polar lipids, including an amine-containing phospholipid with chromatographic mobility similar to that of phosphatidylinositol. The polar lipid fatty acids were dominated by anteiso-C(17 : 0) and iso-C(16 : 0). The genome included a chromosome of 3.94 Mbp (G+C content 61.5 mol%) encoding 3285 proteins and two plasmids of 59.8 and 14.8 kBp. Based on the data obtained in this study, a new genus and species, Natronoglycomyces albus gen. nov., sp. nov, is proposed with the type strain ACPA22(T) (=DSM 106290(T)=VKM Ac-2771(T)).