Agromyces seonyuensis sp. nov., isolated from island soil

Abstract

A Gram-positive, non-motile, pale yellow coloured actinobacterial strain designated MMS17-SY077T was isolated from island soil, and its taxonomic position was investigated using a polyphasic approach. Strain MMS17-SY077T grew optimally at 30 °C, at pH 7 and in the absence of NaCl on Reasoner's 2A agar. Based on the 16S rRNA gene sequence analysis, the strain was assigned to the genus Agromyces of the family Microbacteriaceae , and the most related species were Agromyces italicus DSM 16388T (98.8 % sequence similarity), Agromyces allii UMS-62T (98.1 %) and Agromyces terreus DS-10T (97.8 %). Strain MMS17-SY077T formed a distinct cluster within the Agromyces clade in the phylogenetic tree. Genome-based comparative analyses confirmed a clear distinction between the strain and neighbouring species, as the highest orthologous average nucleotide identity and digital DNA–DNA hybridization values with other related species were 77.2 and 21.4% respectively, which were far below the cutoffs for species distinction. The diagnostic polar lipids of MMS17-SY077T were diphosphatidylglycerol and phosphatidylglycerol, and unidentified glycolipids and an unidentified aminolipid were also present. The main isoprenoid quinones were menaquinones with 11 and 12 isoprene units (MK-11 and MK-12), and main fatty acids were anteiso-C15 : 0 (34.4 %) and iso-C16 : 0 (33.2 %). The whole-cell hydrolysates contained rhamnose, ribose and galactose as diagnostic sugars, and l-2,4-diaminobutyric acid as the major diamino acid. The DNA G+C content was 72.1 mol %. Based on phenotypic, chemotaxnomic and phylogenetic characterization, strain MMS17-SY077T should be classified as representing a new species of the genus Agromyces , for which the name Agromyces seonyunensis sp. nov. is proposed (type strain MMS17-SY077T=KCTC 49423T=LMG 31762T).