Pseudoalteromonas ostreae sp. nov., a new bacterial species harboured by the flat oyster Ostrea edulis

Three bacterial strains, named hOe-66(T), hOe-124 and hOe-125, were isolated from the haemolymph of different specimens of the flat oyster Ostrea edulis collected in Concarneau bay (Finistere, France). These strains were characterized by a polyphasic approach, including (i) whole genome analyses with 16S rRNA gene sequence alignment and pangenome analysis, determination of the G+C content, average nucleotide identity (ANI), and in silico DNA-DNA hybridization (isDDH), and (ii) fatty acid methyl ester and other phenotypic analyses. Strains hOe-66(T), hOe-124 and hOe-125 were closely related to both type strains Pseudoalteromonas rhizosphaerae RA15(T) and Pseudoalteromonas neustonica PAMC 28425(T) with less than 93.3% ANI and 52.3% isDDH values. Regarding their phenotypic traits, the three strains were Gram-negative, 1-2 mu m rod-shaped, aerobic, motile and non-spore-forming bacteria. Cells grew optimally at 25 degrees C in 2.5% NaCl and at 7-8 pH. The most abundant fatty acids were summed feature 3 (C-16:1 omega 7c/C-16:1 omega 6c), C-16:0 and C-17:1 omega 8c. The strains carried a genome average size of 4.64 Mb and a G+C content of 40.28 mol%. The genetic and phenotypic results suggested that strains hOe-66(T), hOe-124 and hOe-125 belong to a new species of the genus Pseudoalteromonas. In this context, we propose the name Pseudoalteromonas ostreae sp. nov. The type strain is hOe-66(T) (=CECT 30303(T)=CIP 111911(T)).