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-KR2(T), 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-KR2(T) revealed a clear affiliation with the genus Gracilimonas. Based on phylogenetic analysis, strain CL-KR2(T) showed the closest phylogenetic relationship to Gracilimonas tropica CL-CB462(T), with 16S rRNA gene sequence similarity of 96.6%. DNA-DNA relatedness between strain CL-KR2(T) and G. tropica CL-CB462(T) was 6.7% (reciprocal 9.5 %). Strain CL-KR2(T) 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 degrees C and pH 7.5. The major cellular fatty acids (>= 10.0%) of strain CL-KR2(T) were iso-C-15:0, summed feature 3 (iso-C-15:0 2-OH and/or C-16:1 omega 7c) and iso-C-17:1 omega 9c 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-KR2(T) was 43.2 mol%. The combined phenotypic, chemotaxonomic and phylogenetic data showed that strain CL-KR2(T) could be distinguished from the only member of the genus Gracilimonas with a validly published name. Thus, strain CL-KR2(T) 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-KR2(T) (=KCCM 90206(T)=JCM 18898(T)).