Vibrio coralinecrosis sp. nov., a coral pathogen isolated from the stony coral Galaxea fascicularis in the South China Sea.

A Gram-stain-negative, facultatively anaerobic, motile and rod-shaped bacterium, designated as strain SCSIO 43001T, was isolated from the gastric cavity of the stony coral Galaxea fascicularis in the South China Sea. Previous studies identified this strain as a temperature-dependent coral pathogen, and further ecological analysis revealed that this species is also distributed among other marine invertebrates, including the Pacific oyster Magallana gigas. Strain SCSIO 43001T grew at 10-40 °C (optimum, 28 °C), pH 6.0-10.0 (optimum, 7.0) and in 0.5-10% (w/v) NaCl (optimum, 3-4%). Phylogenetic analysis based on 16S rRNA gene sequences showed that strain SCSIO 43001T belongs to the genus Vibrio, sharing the highest similarities with Vibrio japonicus LMG 29636T (98.2%) and Vibrio xuii LMG 21346T (97.9%). However, phylogenomic comparisons showed that the average nucleotide identity and digital DNA-DNA hybridization values between strain SCSIO 43001T and its closest relatives were below 86.6 and 31.1%, respectively, well below the species-delimitation thresholds. The major cellular fatty acids were summed feature 3 (C16 : 1  ω7c/C16 : 1  ω6c), summed feature 8 (C18  :  1 ω6c or C18  :  1 ω7c) and C16 : 0. The DNA G+C content was 44.5 mol%. Based on combined phenotypic, chemotaxonomic, phylogenetic and phylogenomic polyphasic evidence, strain SCSIO 43001T represents a novel species within the genus Vibrio, for which the name Vibrio coralinecrosis sp. nov. is proposed with the type strain SCSIO 43001T (=MCCC 1K09368T=KCTC 18156T).