Curtobacterium phyllosphaerae sp. nov. and Curtobacterium guangdongense sp. nov., isolated from the citrus phyllosphere

Two yellow-pigmented, Gram-stain-positive and aerobic bacterial strains, designated RRHDQ10 T and RRHDQ66 T , were isolated from citrus leaves collected from a well-known production area located in Renhua County of Guangdong Province, P. R. China. The 16S rRNA gene comparison showed that strain RRHDQ10 T shared the highest similarity to Curtobacterium ammoniigenes NBRC 101786 T (98.32%) and Curtobacterium albidum DSM 20512 T (98.32%), and strain RRHDQ66 T shared that to Curtobacterium flaccumfaciens JCM 9670 T (99.86%) and Curtobacterium allii 20TX0166 T (99.86%). Phylogenetic analyses based on the 16S rRNA gene and genome sequences showed that they belonged to the genus Curtobacterium , among which strain RRHDQ10 T was most closely related to C. ammoniigenes NBRC 101786 T , and strain RRHDQ66 T showed a close relationship with C. flaccumfaciens JCM 9670 T and Curtobacterium herbarum NBRC 103064 T . The genome-derived average nucleotide identity between the two strains and their closely related type strains was below 82.06% and 85.55%, respectively, and the corresponding digital DNA–DNA hybridization values were below 22.3% and 26.2%, respectively. Anteiso-C 15:0 and iso-C 16: 0 were their major fatty acids. Moreover, summed feature 8 (C 18:1 ω 7 c and/or C 18:1 ω6 c) and anteiso-C 17 : 0 served as major components in strains RRHDQ10 T and RRHDQ66 T , respectively. They took menaquinone-9 (MK-9) as the predominant respiratory quinone and ornithine as the principal cell-wall diamino acid. Their major polar lipids were phosphatidylglycerol, diphosphatidylglycerol and three unidentified glycolipids. The genomic DNA G+C contents of strains RRHDQ10 T and RRHDQ66 T were 71.2 and 70.5 mol%, respectively. Based on phenotypic, genotypic and chemotaxonomic analyses, they should be considered as two novel species of the genus Curtobacterium , for which the names Curtobacterium phyllosphaerae sp. nov. and Curtobacterium guangdongense sp. nov. are proposed, with RRHDQ10 T (=GDMCC 1.2671 T =JCM 34831 T ) and RRHDQ66 T (=GDMCC 1.2666 T = JCM 34827 T ) as the type strains, respectively.