Two aerobic, Gram-stain-negative, non-motile and non-spore-forming rods bacterial strains, designated MMSM20T and MMSM24, were isolated from tomato rhizosphere soil and could produce indole-3-acetic acid and siderophore. Phylogenetic analyses based on 16S rRNA gene sequences and 92 core genes showed that strains MMSM20T and MMSM24 belonged to the genus Sphingomonas and were most closely related to three validly published species Sphingomonas jeddahensis G39T, Sphingomonas mucosissima DSM 17494T and Sphingomonas dokdonensis DSM 21029T. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between strains MMSM20T and MMSM24 were 97.6 and 81.0 %, respectively, demonstrating that they were conspecific. The ANI and dDDH values between the two strains and the three type strains above were below the threshold values for species delimitation. The genomic DNA G+C contents of strains MMSM20T and MMSM24 were 66.6 and 66.4 mol%, respectively. The major fatty acids of the two strains were identified as C14 : 0 2OH, summed feature 8 (C18 : 1 ω7c and/or C18 : 1 ω6c); the predominant quinone was ubiquinone 10; the polar lipids comprised diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, sphingoglycolipid and unidentified lipids. Results of phenotypic and genotypic analyses supported that strains MMSM20T and MMSM24 represent a novel species of the genus Sphingomonas, for which the name Sphingomonas lycopersici sp. nov. is proposed. The type strain is MMSM20T (=GDMCC 1.3401T=JCM 35647T).
Keywords: Sphingomonas; novel species; polyphasic taxonomy; tomato rhizosphere soil.