Sphingomicrobium aestuariivivum sp. nov., isolated from a tidal flat

Abstract

A Gram-stain-negative, aerobic, non-spore-forming, non-flagellated and coccoid, ovoid or rod-shaped bacterial strain, designated AH-M8T, was isolated from a tidal flat sediment collected from Aphae Island in the south-western sea, South Korea. Strain AH-M8T grew optimally at 35 °C, at pH 7.0–8.0 and in the presence of 2.0–3.0  % (w/v) NaCl. A neighbour-joining phylogenetic tree based on 16S rRNA gene sequences revealed that strain AH-M8T belonged to the genus Sphingomicrobium, clustering with the type strain of Sphingomicrobium astaxanthinifaciens, with which it shared 99.0 % 16S rRNA gene sequence similarity. Sequence similarities to the type strains of other species of the genus Sphingomicrobium were 95.4–96.0  %. Strain AH-M8T contained Q-10 as the predominant ubiquinone and C18 : 1ω7c, summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) and C16 : 0 as the major fatty acids. The major polar lipids of strain AH-M8T were phosphatidylglycerol, phosphatidylethanolamine, sphingoglycolipid and one unidentified glycolipid. The major polyamine is triamine sym-homospermidine. The DNA G+C content of strain AH-M8T was 66.7 mol% and its mean DNA–DNA relatedness value with S. astaxanthinifaciens JCM 18551T was 21  %. The differential phenotypic properties, together with the phylogenetic and genetic distinctiveness, revealed that strain AH-M8T is separated from other species of the genus Sphingomicrobium. On the basis of the data presented, strain AH-M8T is considered to represent a novel species of the genus Sphingomicrobium, for which the name Sphingomicrobium aestuariivivum sp. nov. is proposed. The type strain is AH-M8T ( = KCTC 42286T = NBRC 110678T).