A novel bacterial strain (MSC19T) was isolated from a deep-sea sponge Cacospongia mycofijiensis collected in the Mariana Trench at a depth of 2681 m. The cells of the new isolate were Gram-stain-positive, non-motile, oxidase- and catalase-positive, rod-shaped and yellow-coloured. They could grow at 4-32 °C (optimum, 28 °C), pH 5.5-12 (optimum, pH 7.0) and with 0-12 % (w/v) NaCl (optimum, 4 %). The strain's 16S rRNA gene sequence showed 98.41 % similarity to that of Mycetocola saprophilus CM-01T. Phylogenetic analysis further suggested that strain MSC19T represents a new species within the genus Mycetocola. The total genome of MSC19T was approximately 3 196 754 bp in size with a G+C content of 66.43 mol%. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values among MSC19T and other Mycetocola type strains were 70.35-75.37 % (ANIb), 83.79-84.73 % (ANIm) and 20.3-21.7 % (dDDH). The major fatty acids of MSC19T were composed of anteiso-C15 : 0, iso-C16 : 0 and anteiso-C17 : 0, and its predominant menaquinones were MK-10 and MK-9. The polar lipids of MSC19T mainly consisted of diphosphatidylglycerol, phosphatidylglycerol and glycolipid. The diagnostic cell-wall diamino acid was lysine. Combined molecular, physiological, biochemical and chemotaxonomic analyses suggest that strain MSC19T represents a novel species of the genus Mycetocola, for which the name Mycetocola spongiae sp. nov. is proposed. The type strain is MSC19T (=MCCC 1K06265T=KCTC 49701T).
Keywords: Mycetocola spongiae; deep-sea sponge; polyphasic taxonomy.