Sphingomonas jatrophae sp. nov. and Sphingomonas carotinifaciens sp. nov., two yellow-pigmented endophytes isolated from stem tissues of Jatropha curcas L.

Two yellow-pigmented isolates, S5-249 and L9-754, originating from surface-sterilized plant tissues of Jatropha curcas L. (Jatropha) cultivars were characterized using a polyphasic taxonomic approach. Strains S5-249 and L9-754 had 16S rRNA genes sharing 94.2 % sequence similarity with each other and 91.6-97.2 % sequence similarity with those of other species in the genus Sphingomonas, suggesting that they represent two potentially novel species. The 16S rRNA gene sequences of strains S5-249 and L9-754 shared the highest similarity to that of Sphingomonas sanguinis NBRC 13937 (96.1 and 97.2 %, respectively). The genomic DNA G+C contents of strains S5-249 and L9-754 were 66.9 and 68.5 mol%, respectively. The respiratory quinone was determined to be Q-10, and the major polyamine was homospermidine. Strains S5-249 and L9-754 contained summed feature 7 (comprising C18 : 1ω7c, C18 : 1ω9t and/or C18 : 1ω12t), C16 : 1, C14 : 0 2-OH and summed feature 4 (C16 : 1ω7t, iso-C15 : 0 2-OH and C16 : 1ω7c) as the major cellular fatty acids. The predominant polar lipids were phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine and sphingoglycolipid. The average nucleotide identity (ANI) values between S. sanguinis NBRC 13937 and the two type strains (S5-249 and L9-754) were 72.31 and 77.73 %, respectively. Digital DNA-DNA hybridization (dDDH) studies between the novel strains (S5-249 and L9-754) and other species of the genus Sphingomonas were well below the thresholds used to discriminate between bacterial species. The results of dDDH and physiological tests allowed genotypic and phenotypic differentiation of the strains from each other as well as from the species of the genus Sphingomonas with validly published names. These data strongly support the classification of the strains as representatives of novel species, for which we propose the names Sphingomonas jatrophae sp. nov. (type strain S5-249=DSM 27345=KACC 17593) and Sphingomonas carotinifaciens sp. nov. (type strain L9-754=DSM 27347=KACC 17595).