Psychrosphaera aestuarii sp. nov. and Psychrosphaera haliotis sp. nov., isolated from the marine environment, and emended description of the genus Psychrosphaera

Abstract

Two motile, rod-shaped and agarolytic bacterial strains, designated PSC101T and KDW4T, were isolated from seawater and gut microflora of abalone, respectively, collected from the South Sea (Republic of Korea). Cells were Gram-stain-negative, aerobic, catalase- and oxidase-positive. Strains PSC101T and KDW4T showed high 16S rRNA gene sequence similarity to each other (98.6 %). Psychrosphaera saromensis SA4-48T was the nearest neighbour of strains PSC101T and KDW4T with 96.6 % and 97.0 % 16S rRNA gene sequence similarity, respectively. DNA–DNA relatedness among strains PSC101T, KDW4T and Psychrosphaera saromensis KCTC 23240T was less than 70 %. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the two isolates belonged to the genus Psychrosphaera and formed a distinct phyletic line from Psychrosphaera saromensis SA4-48T. The common major cellular fatty acids of the two novel isolates were C16 : 0, C17 : 1ω8c and summed feature 3 (C16 : 1ω6c/C16 : 1ω7c). Flexirubin-type pigments were absent. The main ubiquinone was UQ-8 and the DNA G+C content of strains PSC101T and KDW4T was 49.5 and 42.5 mol%, respectively. The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol and an unidentified amino lipid. On the basis of the polyphasic characterization of the two strains, it is suggested that the two isolates represent two novel species of the genus Psychrosphaera , for which the names Psychrosphaera aestuarii sp. nov. (type strain, PSC101T = KCTC 32274T = JCM 19496T) and Psychrosphaera haliotis sp. nov. (type strain, KDW4T = KCTC 22500T = JCM 16340T) are proposed. An emended description of the genus Psychrosphaera is also proposed.