Rheinheimera longhuensis sp. nov., isolated from a slightly alkaline lake, and emended description of genus Rheinheimera Brettar et al. 2002

Abstract

The bacterial strain LH2-2T was isolated from freshwater of Longhu Lake, a slightly alkaline lake (pH 8.8) in north-east China. Cells of strain LH2-2T were Gram-staining-negative, non-spore-forming rods, 0.3–0.5 µm wide and 2.0–4.0 µm long. Cells were motile by means of a single polar flagellum. The strain was strictly aerobic and heterotrophic and oxidase- and catalase-positive. Growth occurred at 0–36 °C (optimum, 26–34 °C), pH 6.5–11 (optimum, pH 8.0–8.6) and in the presence of 0–2 % (w/v) NaCl (optimum, 1 %). Strain LH2-2T contained Q-8 as the major respiratory quinone. The major fatty acids were summed feature 3 (C16 : 1ω7c and/or iso-C15 : 0 2-OH; 21.9 %), C17 : 1ω8c (18.9 %), C18 : 1ω7c (16.4 %) and C16 : 0 (12.7 %) after growth on marine agar 2216. The DNA G+C content was 47 mol% (T m). The 16S rRNA gene and a conserved portion of the gyrB gene were sequenced and used for phylogenetic analyses. Phylogenetic trees based on 16S rRNA gene and gyrB sequences showed that strain LH2-2T was associated with the genus Rheinheimera and closely related to the type strains of Rheinheimera species, and showed the highest 16S rRNA gene sequence similarity to Rheinheimera pacifica KMM 1406T (97.4 %), R. aquimaris SW-353T (97.1 %) and R. chironomi K19414T (96.5 %). The DNA–DNA relatedness of strain LH2-2T to R. pacifica NBRC 103167T, R. aquimaris JCM 14331T and R. chironomi LMG 23818T was 39, 31 and 23 %, respectively. Based on these results, it is concluded that strain LH2-2T represents a novel species of the genus Rheinheimera , for which the name Rheinheimera longhuensis sp. nov. is proposed. The type strain is LH2-2T ( = CGMCC 1.7003T  = NBRC 105632T). An emended description of the genus Rheinheimera is also provided.