Arthrobacter wenxiniae sp. nov., a novel plant growth-promoting rhizobacteria species harbouring a carotenoids biosynthetic gene cluster.

A bacterial strain, designated AETb3-4 T was isolated from the rhizosphere of lily. Comparison of 16S rRNA gene sequences showed that the sequence from strain AETb3-4 T exhibits high sequence similarity with those of Arthrobacter silviterrae KIS14-16 T (97.9%), Arthrobacter livingstonensis LI2 T (97.2%) and Arthrobacter stackebrandtii CCM 2783 T (97.0%). Whole genome average nucleotide identity (ANI) and the digital DNA-DNA hybridization (dDDH) values between strain AETb3-4T and the reference strains A. silviterrae DSM 27180 T , A. livingstonensis L12 T and A. stackebrandtii DSM 16005 T were below 83.6% and 27.7%, respectively, values which are considerably below the proposed thresholds for the species delineation, consistent with the proposal that strain AETb3-4 T represents a novel species. The genome size of strain AETb3-4 T is 4.33 Mb and the genomic DNA G + C content is 67.3%. The main polar lipids were identified as phosphatidylglycerol, diphosphatidylglycero, phosphatidylinositol and an unidentified glycolipid. The major fatty acids (> 10%) were identified as anteiso-C 15: 0 and anteiso-C 17: 0 . The predominant menaquinone was found to be menaquinone 9 (MK-9) (H 2 ) (82.2%). Phenotypic tests allowed the strain to be differentiated from its close phylogenetic neighbors. Based on the results obtained, it is proposed that the strain AETb3-4 T (= CFCC 16390 T  = LMG 31708 T ) represents a novel species in the genus Arthrobacter, for which the names Arthrobacter wenxiniae sp. nov. is proposed. In addition, the novel strain AETb3-4 T has multiple plant growth-promoting characters including ACC-deaminase activity and production of IAA. Furthermore, the genome contains secondary metabolite biosynthesis gene clusters, including a carotenoid biosynthetic gene cluster, suggesting potential capacities for secondary metabolite synthesis. These data suggest that strain AETb3-4 T may have potential applications both in medicine and sustainable agriculture.