The diversity of Pseudomonas species isolated from fish farms in Turkey

The prevalence of Pseudomonas species in freshwater fish and water from aquaculture farms in Turkey was determined on a monthly basis, in the period covering 2013-2017 and two seasons of 2018. The farms included in the study were located in six different regions of Turkey. A total of 90 Pseudomonas strains were isolated from water and diseased and healthy fish, and were classified under 20 species. The phenotypic characterization of the strains was based on oxidase and catalase activities, haemolysis, tolerance to temperature and sodium chloride, the production of fluorescent pigments and antibiotic resistance spectra. The phylogenetic identification of the 90 isolates was performed by a 4-gene multilocus sequence analysis, based on the partial sequencing of the 16S rRNA, gyrB, rpoB and rpoD genes. This is the first report on the isolation of several Pseudomonas species, namely, P. brenneri, P. defensor, P. haemolytica, P. lactis, P. lundensis, P. lurida, P. mandelii, P. meridiana, P. migulae, P. proteolytica, P. simiae, and P. weihenstephanensis, from freshwater salmonid fish. Two of these species, P. haemolytica and P. lactis have been isolated for the first time from fish farms, an environment quite different from their original isolation source, raw milk. Furthermore, seven putative new Pseudomonas species were isolated from water and farmed rainbow trout. During the 2013 to 2018 period, several Pseudomonas species were detected to have spread from the Aegean and Central Anatolia regions to the Eastern Anatolia and Black Sea regions.