Sphingomonas folii sp. nov., Sphingomonas citri sp. nov. and Sphingomonas citricola sp. nov., isolated from citrus phyllosphere

Abstract

Three novel Gram-stain-negative, aerobic and rod-shaped bacterial strains, designated RHCKR7T, RRHST34T and RHCKR47T, were isolated from phyllosphere of healthy citrus collected in Renhua County, Guangdong Province, PR China. Phylogenetic analyses showed that they belonged to the genus Sphingomonas , among which both strains RHCKR7T and RRHST34T showed a close relationship with Sphingomonas yunnanensis YIM 003T with 16S rRNA gene similarity of 99.0 and 99.1%, respectively, and the similarity between the two novel strains was 99.2%, meanwhile strain RHCKR47T was most closely related to Sphingomonas palmae KACC 17591T (99.5%). Genome-derived average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH) values between closely related novel strains RHCKR7T and RRHST34T were 90.43 and 40.80 %, respectively, and their most closely related type strain, S. yunnanensis YIM 003T, showed 90.43 % ANI and 40.7 % dDDH with RHCKR7T and 90.21 % and 42.9 % with RRHST34T, respectively, and the corresponding values between strain RHCKR47T and S. palmae KACC 17591T were 85.53 % and 29.30%, respectively. They all took C14 : 0 2-OH and summed feature 8 (C18 : 1  ω6c and/or C18 : 1  ω7c) as the major fatty acids, and ubiquinone 10 as the predominant respiratory quinone. The major polar lipids contained sphingoglycolipid, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine and unidentified phospholipids. sym-Homospermidine was the major polyamine. Based on phenotypic, genotypic and chemotaxonomic analyses, the new isolates should be considered as representing three novel species of the genus Sphingomonas , for which the names Sphingomonas folli sp. nov., Sphingomonas citri sp. nov. and Sphingomonas citricola sp. nov. are proposed with RHCKR7T (=GDMCC 1.2663T=JCM 34794T), RRHST34T (=GDMCC 1.2665T=JCM 34796T) and RHCKR47T (=GDMCC 1.2664T=JCM 34795T) as the type strains, respectively.