Search

In this study, two endophytic bacterial strains designated JS21-1T and S6-262T isolated from leaves of Elaeis guineensis and stem tissues of Jatropha curcas respectively, were subjected for polyphasic taxonomic approach. On R2A medium, colonies of strains JS21-1T and S6-262T are orange and yellow, respectively. Phylogenetic analyses using 16S rRNA gene sequencing and whole-genome sequences placed the strains in distinct clades but within the genus Sphingomonas. The DNA G + C content of JS21-1T and S6-262T were 67.31 and 66.95%, respectively. Furthermore, the average nucleotide identity and digital DNA-DNA hybridization values of strains JS21-1T and S6-262T with phylogenetically related Sphingomonas species were lower than 95% and 70% respectively. The chemotaxonomic studies indicated that the major cellular fatty acids of the strain JS21-1T were summed feature 8 (C18:1 ω7c and/or C18:1 ω6c), C16:0, and C14:0 2OH; strain S6-262T possessed summed feature 3 (C16:1 ω7c and/or iso-C15:0 2-OH) and summed feature 8 (C18:1 ω6c and/or C18:1 ω7c). The major quinone was Q10, and the unique polyamine observed was homospermidine. The polar lipid profile comprised of mixture of sphingoglycolipid, phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol and certain uncharacterised phospholipids and lipids. Based on this polyphasic evidence, strains JS21-1T and S6-262T represent two novel species of the genus Sphingomonas, for which the names Sphingomonas palmae sp. nov. and Sphingomonas gellani sp. nov. are proposed, respectively. The type strain of Sphingomonas palmae sp. nov. is JS21-1T (= DSM 27348T = KACC 17591T) and the type strain of Sphingomonas gellani sp. nov. is S6-262T (= DSM 27346T = KACC 17594T).

The 16S rRNA gene sequences of

Roseobacters are a diverse and globally abundant group of Alphaproteobacteria within the Rhodobacteraceae family. Recent studies and the cophenetic correlations suggest that the 16S rRNA genes are poor phylogenetic markers within this group. In contrast, the cophenetic correlation coefficients of the core-gene average amino acid identity (cAAI) and RpoC protein sequences are high and likely more predictive of relationships. A maximum-likelihood phylogenetic tree calculated from 53 core genes demonstrated that some of the current genera were either polyphyletic or paraphyletic. The boundaries of bacterial genera were redefined based upon the cAAI, the percentage of conserved proteins, and phenotypic characteristics and resulted in the following taxonomic proposals. Loktanella vestfoldensis, Loktanella litorea, Loktanella maricola, Loktanella maritima, Loktanella rosea, Loktanella sediminilitoris, Loktanella tamlensis, and Roseobacter sp. CCS2 should be reclassified into the novel genus Yoonia. Loktanella hongkongensis, Loktanella aestuariicola, Loktanella cinnabarina, Loktanella pyoseonensis, Loktanellasoe soekkakensis and Loktanella variabilis should be reclassified in the novel genus Limimaricola. Loktanella koreensis and Loktanella sediminum should be reclassified in the novel genus Cognatiyoonia. Loktanella marina should be reclassified in the novel genus Flavimaricola. Aestuariivita atlantica should be reclassified in the novel genus Pseudaestuariivita. Thalassobius maritima should be reclassified in the novel genus Cognatishimia. Similarly, Ruegeria mobilis, Ruegeria scottomollicae, Ruegeria sp. TM1040 and Tropicibacter multivorans should be reclassified in the genus Epibacterium. Tropicibacter litoreus and Tropicibacter mediterraneus should be reclassified in the genus Ruegeria. Thalassobius abyssi and Thalassobius aestuarii should be reclassified in the genus Shimia. Citreicella aestuarii, Citreicella manganoxidans, Citreicella marina, Citreicella thiooxidans, Pelagibaca bermudensis and Thiobacimonas profunda should be reclassified in the genus Salipiger. Nautella italica should be reclassified in the genus Phaeobacter. Because these proposals to reclassify the type and all others species of Citreicella, Nautella, Pelagibaca and Thiobacimonas, these genera are not used in this taxonomy.