Shewanella oncorhynchi isolated from a recirculatory aquaculture system (RAS) in Alberta, Canada

Certain Shewanella spp. cause spoilage of seafood. However, Shewanella from fish production facilities in Canada have not yet been characterized. In our study, we first isolated Shewanella oncorhynchi S23-S33 (S2-3) from the water in a rainbow trout tank from a recirculating aquaculture system (RAS) facility located in Alberta, Canada. Later we found another strain (FD-1) from the biofilters from the same facility. Whole genome sequencing revealed that both strains possess gene clusters for the biosynthesis of eicosapentaenoic acid and we confirmed the production in FD-1 by gas chromatography. Phylogenetic analyses showed the close relatedness of FD-1 and S2-3 to S. oncorhynchi S-1. Rainbow trout filets inoculated with FD-1 turned brown in colour compared to uninoculated. However, when we inoculated retail pink salmon (Oncorhynchus gorbuscha) with either FD-1 or S2-3, we did not observe the brown colour change. The storage time had a significant (P < 0.0001) impact on the lightness (L^*), red/green (a^*), and yellow/blue (b^*) of pink salmon. In summary, our research note records the preliminary characterization of Shewanella from a RAS trout facility in Alberta, Canada.