Description of three new Pseudomonas species isolated from aquarium fish: Pseudomonas auratipiscis sp. nov., Pseudomonas carassii sp. nov. and Pseudomonas ulcerans sp. nov

Pseudomonas species constitute a significant group of pathogens in aquarium fish and frequently cause haemorrhagic septicaemia. This study conducted a taxonomic characterization of Pseudomonas isolates from aquarium fish exhibiting deep ulceration and general disease signs. A polyphasic approach was employed to ascertain the taxonomic affiliation of the strains. The overall genome relatedness indices of digital DNA–DNA hybridization (dDDH) and average nucleotide identity (ANI) between the strains and the other members of the genus Pseudomonas were found to be below the established thresholds of 70 and 95–96%, respectively. Whole-genome based phylogenetic analysis revealed that strains 119P^T and 120P were closely related to P. arcuscaelestis. Strain 137P^T was related to P. peradeniyensis, while strains 147P^T and 148P were closely related to P. japonica. The morphological, physiological, and biochemical characteristics of the strains and the genome relatedness indices of dDDH and ANI below the established thresholds confirmed the classification of the strains as three novel species. Genome analyses of the strains were also conducted to determine their biosynthesis-related gene clusters, virulence features and ecological distribution patterns. Based on polyphasic characterization, the strains 119P^T, 120P, 137P^T, 147P^T, and 148P are novel species within the genus Pseudomonas, for which the following names are proposed: Pseudomonas auratipiscis sp. nov., with the strain 119P^T as the type strain (=DSM 117162 ^T, =LMG 33381^T); Pseudomonas carassii sp. nov., with the strain 137P^T as the type strain (=DSM 117060^T, =LMG 33378^T); and Pseudomonas ulcerans sp. nov. 147P^T, as the type strain (=DSM 117163^T, =LMG 33377^T).