Reclassification of Pasteurella skyensis as Phocoenobacter skyensis comb. nov. and description of Phocoenobacter atlanticus sp. nov. isolated from diseased Atlantic salmon (Salmo salar) and lumpfish (Cyclopterus lumpus), with subdivision into Phocoenobacter atlanticus subspecies atlanticus subsp. nov. and Phocoenobacter atlanticus subspecies cyclopteri subsp. nov.

Abstract

Gram-negative bacteria, similar in 16S rRNA gene sequence to Pasteurella skyensis, have been irregularly cultured from diseased Atlantic salmon (Salmo salar) sea-farmed in Norway since the 1980s and more commonly in later years from diseased lumpfish (Cyclopterus lumpus) farmed in the northeast Atlantic area. Phenotypic and genetic analyses confirmed that the majority of Norwegian isolates in the present study, cultured from both salmon and lumpfish, are closely related to, yet distinct from, P. skyensis and represent a hitherto undescribed species. We further argue, based on genetic similarity levels, that the original placement of P. skyensis within Pasteurella was erroneous and that this species belongs within Phocoenobacter, as Phocoenobacter skyensis comb. nov. Accordingly, we propose the name Phocoenobacter atlanticus sp. nov. for the new species characterized here. Furthermore, this species separates into two genetically and phenotypically distinct lineages, respectively, associated with Atlantic salmon and lumpfish, and for which we propose the names Ph. atlanticus subsp. atlanticus subsp. nov. and Ph. atlanticus subsp. cyclopteri subsp. nov., respectively. The type strain for Ph. atlanticus subsp. atlanticus subsp. nov. is strain NVIB3624^T (NCIMB 15512^T, CCUG 77520^T), and the type strain for Ph. atlanticus subsp. cyclopteri subsp. nov. is strain NVIO9100^T (NCIMB 15511^T, CCUG 77521^T).