Gracilimonas rosea sp. nov., isolated from tropical seawater, and emended description of the genus Gracilimonas

Abstract

A Gram-staining-negative, non-motile, spore-forming, rod-shaped, marine bacterial strain, CL-KR2T, was isolated from tropical seawater near Kosrae, an island in the Federated States of Micronesia. Analysis of the 16S rRNA gene sequence of strain CL-KR2T revealed a clear affiliation with the genus Gracilimonas . Based on phylogenetic analysis, strain CL-KR2T showed the closest phylogenetic relationship to Gracilimonas tropica CL-CB462T, with 16S rRNA gene sequence similarity of 96.6 %. DNA–DNA relatedness between strain CL-KR2T and G. tropica CL-CB462T was 6.7 % (reciprocal 9.5 %). Strain CL-KR2T grew in the presence of 1–20 % sea salts and the optimal salt concentration was 3.5–5 %. The temperature and pH optima for growth were 35 °C and pH 7.5. The major cellular fatty acids (≥10.0 %) of strain CL-KR2T were iso-C15 : 0, summed feature 3 (iso-C15 : 0 2-OH and/or C16 : 1ω7c) and iso-C17 : 1ω9c and the only isoprenoid quinone was MK-7. The polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, an unidentified phospholipid, two unidentified glycolipids and two unidentified lipids. The genomic DNA G+C content of strain CL-KR2T was 43.2 mol%. The combined phenotypic, chemotaxonomic and phylogenetic data showed that strain CL-KR2T could be distinguished from the only member of the genus Gracilimonas with a validly published name. Thus, strain CL-KR2T should be assigned to a novel species in the genus Gracilimonas , for which the name Gracilimonas rosea sp. nov. is proposed. The type strain is CL-KR2T ( = KCCM 90206T = JCM 18898T).