Isolation and experimental challenge of cultured burbot (Lota lota maculosa) with Flavobacterium columnare and Aeromonas sp. isolates.

Burbot (Lota lota maculosa) are a potential new species for commercial aquaculture. As burbot culture expands, there is a need to further define pathogen susceptibility and characterize aspects of the burbot immune response in an effort to assess fish health. A recent clinical diagnostic case from juvenile burbot reared at a commercial production facility resulted in the isolation and identification ofFlavobacterium columnarealong with severalAeromonasspp. TheF. columnareisolate was assigned to genetic group 1 via multiplex PCR, a genetic group commonly associated with columnaris disease cases in rainbow trout (Oncorhynchus mykiss). Virulence of theF. columnareisolate was assessed in vivo in both juvenile burbot and rainbow trout. Additionally, several of theAeromonassp. case isolates were identified via sequencing (16S rRNA,gyrBandrpoD) and a putativeA.sobriaisolate (BI-3) was used to challenge burbot, along with a known virulentAeromonassp. (A141), but BI-3 was not found to be virulent. Burbot were refractory toF. columnarewhen challenged by immersion, and it is likely that this is a secondary pathogen for burbot. Although refractory in burbot, the identifiedF. columnareisolate (BI-1) was found to be virulent in rainbow trout.