Occultella gossypii sp. nov., an alkali-resistant isolate from soil sampled in a cotton field

A non-spore-forming, motile and alkali-resistant actinobacterium, designated N2-46^T, was isolated from an alkaline soil sample collected from a cotton field in the Xinjiang region of PR China. Strain N2-46^T formed creamy colonies on tryptone soy agar and managed to survive in extreme alkaline conditions at a pH value of 11. Strain N2-46^T displayed the highest 16S rRNA gene similarity of 99.65 % to Haloactinobacterium kanbiaonis HY164^T, followed by Occultella aeris F300^T (99.61%) and Occultella glacieicola T3246-1^T (98.54 %). 16S rRNA-directed phylogenetic analysis showed that strain N2-46^T was embedded in a subclade with O. aeris F300^T with a bootstrap value of 71.8 %. The phylogenetic tree based on core genes of genome sequences showed that strain N2-46^T formed a unique subclade next to H. kanbiaonis HY164^T and O. aeris F300^T with a bootstrap value of 100 %. Digital DNA-DNA hybridization and the average nucleotide identity analyses showed that strain N2-46^T displayed the highest values of 67.1 % (63.2-70.7 %) and 91.82 % with H. kanbiaonis HY164^T, respectively. Comparative genomic analysis indicated that strain N2-46^T and its three closest neighbours exhibited comparable distribution patterns in heavy metal resistance genes and biosynthetic gene clusters, while displaying distinctions probably related to ecological adaptation. MK-8(H₄) was identified as the predominant isoprenoid quinone. The main fatty acids were identified as iso-C_14 : 0 and anteiso-C_15 : 0. Polar lipids are composed of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, mono and diacylated phosphatidylinositol dimannosides, as well as several uncharacterized polar lipid, glycolipid, and phospholipids. Genotypic and physiological analyses support the view that strain N2-46^T (=JCM 34413^T=CGMCC 1.18819^T) should be classified as a novel species of the genus Occultella, for which the name Occultella gossypii sp. nov. is proposed.