Arcicella rigui sp. nov., isolated from water of a wetland, and emended descriptions of the genus Arcicella , Arcicella aquatica , Arcicella rosea and Arcicella aurantiaca

Abstract

A bacterial strain, designated NSW-5T, was isolated from a water sample taken from Niao-Song Wetland Park in Taiwan and characterized using a polyphasic taxonomic approach. Cells of strain NSW-5T were strictly aerobic, Gram-stain-negative, non-motile and polymorphic, being straight, vibrioid, curved and spiral-shaped rods surrounded by a thick capsule and forming light pink-coloured colonies. Some rings consisting of several cells were present. Growth occurred at 10–40 °C (optimum, 25 °C), with 0–3.0 % NaCl (optimum, 0 %) and at pH 6.0–8.0 (optimum, pH 7.0). Phylogenetic analyses based on 16S rRNA gene sequences showed that strain NSW-5T belonged to the genus Arcicella with sequence similarities of 98.6, 98.0 and 97.3 % with Arcicella aquatica NO-502T, Arcicella rosea TW5T and Arcicella aurantiaca TNR-18T, respectively. The predominant cellular fatty acids were summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c; 20.8 %), C16 : 0 (14.6 %), iso-C15 : 0 (13.8 %), C16 : 1ω5c (12.5 %) and C18 : 0 (11.4 %), and the only respiratory quinone was MK-7. The polar lipid profile consisted of phosphatidylethanolamine and several uncharacterized glycolipids, aminolipids, phospholipids and aminophospholipids. The DNA G+C content of strain NSW-5T was 44.1 mol%. The DNA–DNA relatedness of strain NSW-5T with respect to recognized species of the genus Arcicella was less than 70 %. On the basis of phylogenetic inference and phenotypic data, strain NSW-5T should be classified as a representative of a novel species, for which the name Arcicella rigui sp. nov. is proposed. The type strain is NSW-5T ( = KCTC 23307T = BCRC 80260T). Emended descriptions of the genus Arcicella and of Arcicella aquatica , Arcicella rosea and Arcicella aurantiaca are also proposed.