Acinetobacter piscicola sp. nov., isolated from diseased farmed Murray cod (Maccullochella peelii peelii).

A taxonomic study was carried out on strain LW15, which was isolated from the external lesions of diseased farmed Murray cod (Maccullochella peelii peelii) from an intensive culture pond. Cells of strain LW15 were Gram-negative, facultative-anaerobic, non-motile, and both coccobacillus- and bacillus-shaped. Growth was observed at NaCl concentrations of 0-2 % (w/v) (optimum, 0 %), 4-32 °C (optimum, 25-28 °C) and pH 5.0-9.0 (optimum, 7.0). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain LW15 was affiliated to the genus Acinetobacter, showing the highest similarity to Acinetobacter guillouiae CIP 63.46 (97.7 %) and other Acinetobacter species with validly published names (93.5-97.6 %). Whole-genome sequencing and phylogeny reconstruction based on a core set of 1061 Acinetobacter genes indicated that strain LW15 was most closely related to the clade formed by A. guillouiae CIP 63.46 and Acinetobacter bereziniae CIP 70.12 and distantly related to any of the described species of genus Acinetobacter. Furthermore, strain LW15 could be distinguished from all known Acinetobacter species by its ability to assimilate β-alanine and l-arginine, but not d-glucose. The principal fatty acids were C18 : 1ω9c, C16 : 0 and C16 : 1ω7c/C16 : 1ω6c. The major respiratory quinone was Q-9. Polar lipids of strain LW15 comprised diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, four phospholipids, aminolipid and two unknown lipids. Based on its phenotypic and genotypic data, strain LW15 represents a novel species of the genus Acinetobacter, for which the name Acinetobacterpiscicola sp. nov. is proposed. The type strain is LW15 (=MCCC 1K03337=CICC 24241=KCTC 62134=JCM 32101).