Pukyongiella litopenaei gen. nov., sp. nov., a novel bacterium isolated from the gut content of a whiteleg shrimp Litopenaeus vannamei.

A Gram-negative, aerobic bacterium, designated as SH-1T, was isolated from the gut content of a whiteleg shrimp, Litopenaeus vannamei collected in a shrimp farm in South Korea. The bacterial cells were ovoid rod-shaped, non-motile, oxidase-positive and catalase-negative. Growth was observed at 20–35 °C (optimum, 30 °C), pH 5.0–9.5 (pH 8.5) and in the presence of 0–6 % (w/v) NaCl (2–3 %). The major polar lipids were phosphatidylglycerol, phosphatidylinositolmannoside, unidentified aminolipid and two unidentified lipids. The G+C content was 66.1 mol% and the predominant respiratory quinone was Q-10. Phylogenetic analysis based on the 16S rRNA gene sequences showed that strain SH-1T was placed in a distinct clade with Primorskyibacter marinus PX7T (96.97 % sequence similarity), Pontibaca methylaminivorans DSM 21219T (96.03 %) and Pelagivirga sediminicola BH-SD19T (95.02 %) in the family Rhodobacteraceae and distantly related with them to be a new genus. The digital DNA–DNA hybridization (dDDH), average nucleotide identity (ANI) and average amino acid identity (AAI) values calculated from whole-genome-sequence comparison between the SH-1T and the close species were in the ranges of 19.0–19.8, 73.8–74.9 and 64.1–65.9 %, respectively. Based on the polyphasic analysis presented in this study, we suggest that strain SH-1T represents a novel genus and species in the family Rhodobacteraceae , for which the name Pukyongiella litopenaei gen. nov., sp. nov. is proposed. The type strain of Pukyongiella litopenaei is SH-1T (=KCTC 62276T=MCCC 1K04072T).