Parashewanella tropica sp. nov., a mesophilic bacterium isolated from a marine sponge from Chuuk lagoon, Federated States of Micronesia, and emended description of the genus Parashewanella

Abstract

A mesophilic, straight-rod-shaped, non-flagellated bacterium, designated MEBiC05444(T), was isolated from a marine sponge collected from Chuuk lagoon, Federated States of Micronesia. The strain was Gram-negative, catalase- and oxidase-positive, and facultative anaerobic. The isolate aerobically grew at 8-38 degrees C (optimum, 24-32 degrees C), pH 4.0-10.0 (pH 7.0-7.5) with an absolute requirement for Na+ up to 6 % (w/v) NaCl (2 %). Phylogenetic analyses based on 16S rRNA gene sequences revealed that MEBiC05444(T) belonged to the family Shewanellaceae, within the class Gammaproteobacteria. Strain MEBiC05444(T) showed highest 16S rRNA gene sequence similarity to Parashewanella curva C51(T), followed by [Shewanella] irciniae UST040317-058(T) and Parashewanella spongiae HJ039(T) (98.9 %, 97.2 and 95.7 %, respectively). In the phylogenetic tree based on the 16S rRNA gene sequences, MEBiC05444(T) formed a cluster with P. curva C51(T), but the average nucleotide identity value between the two strains was 82 %, thus confirming their separation at species level. The major fatty acids were iso-C-15 : 0 (19.7 %), summed feature 3 (composed of C-16 : 1 omega 7c and/or C-16 : 1 omega 6c; 16.1 %) and C-17 : 1 omega 8c (10.2 %). The only detected respiratory quinone was ubiquinone Q-8. The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, three unidentified aminoglycolipids, two unidentified glycolipids, an unidentified aminoglycophospholipid and an unidentified lipid. The genomic DNA G+C content of strain MEBiC05444T was 40.8 mol%. Based on the results of polyphasic analysis, the strain represents a novel species of the genus Parashewanella, distinct from P. curva C51(T), [Shewanella]irciniae UST040317-058T and P. spongiae HJ039(T) for which the name Parashewanellatropica sp. nov. is proposed with type strain MEBiC05444(T) (=KCCM 43304(T)=JCM 16653(T)).