Abstract
A Gram-stain negative, non-flagellated, beige-pigmented, circular, catalase-positive, oxidase-positive bacterium, designated G4T, was isolated from gut microflora of top shell (Trochus maculatus Linnaeus) collected from Diwanggong market, Weihai, People's Republic of China. The novel isolate was able to grow at 4-42°C (optimum 25-33°C), pH 7.0-9.0 (optimum 6.5-7.0) and with 0.0-11.0% NaCl (optimum 2.0-3.0%, w/v). Analysis of 16S rRNA gene sequence revealed that strain G4T shared the highest 16S rRNA gene sequence similarities with Oceaniglobus ichthyenteri YLY08T (96.6%), followed by Oceaniglobus indicus 1-19bT (95.3%). The genome of strain G4T, with 32 assembled contigs, was 4.5Mb long with a G+C content of 65.3mol%. DNA-DNA hybridization values of the isolate against the closely related type strains were far below the 70% limit for species delineation. The average amino acid identity, average nucleotide identity and digital DNA-DNA genome hybridization relatedness between strain G4T and the closely related members of the genus Oceaniglobus, Oceaniglobus indicus1-19bT and Oceaniglobus ichthyenteri YLY08T were 71.3, 76.4 and 20.0%, and 75.0, 76.3 and 19.4%. The major cellular fatty acid was summed feature 8 (C18:1ω7c and/or C18:1ω6c). The sole respiratory quinone was Q-10. The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol and phosphatidyldimethylethanolamine. The results of phenotypical, phylogenetic and biochemical analyses indicated that strain G4T represents a novel species in genus Oceaniglobus within the family Rhodobacteraceae, for which the name Oceaniglobus trochenteri sp. nov. is proposed. The type strain is G4T (= MCCC 1K04356T = KCTC 82506T).
Highlights
Marine bacteria play an important role in marine ecology, many bacterial strains have been isolated and characterized taxonomically from coastal marine environments and marine organisms
Analysis of the 16S rRNA gene sequences revealed that strain G4T belonged to the genus Oceaniglobus, within the family Rhodobacteraceae
The neighbour-joining phylogenetic tree (Fig. 1) revealed that strain G4T, O. ichthyenteri and O. indicus formed an monophyletic cluster, with high bootstrap support (99%). It indicated that strain G4T might represent a novel species of the genus Oceaniglobus
Summary
Marine bacteria play an important role in marine ecology, many bacterial strains have been isolated and characterized taxonomically from coastal marine environments and marine organisms. At the time of writing, the genus Oceaniglobus consists of two species both from the marine environment, including Oceaniglobus indicus (type species) from sea water (Li et al 2017) and Oceaniglobus ichthyenteri from the gut of sea bass (Wang et al 2019). For researching bacterial diversity in the gut of top shell and isolating potential probiotics, we carried out a culture-dependent bacterial isolation from the gastrointestinal tract of Trochus maculatus Linnaeus. A novel bacterial strain was isolated and designated strain G4T. The aim of this study was to validate the existence of novel species of the genus Oceaniglobus on the basis of phylogenetic, genotypic and phenotypic data
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