Abstract

This study evaluated the probiotic potential of the biofilm formed by the strain Pseudomonas sp. RGM2144 on rainbow trout survival. When challenged with the fish pathogen Flavobacterium psychrophylum, Pseudomonas sp. RGM2144 increased rainbow trout survival to 92.7 +/- 1.2% (control: 35.3 +/- 9.5%, p<.0001). The draft genome of Pseudomonas sp. RGM2144 is 6.8 Mbp long, with a completeness 100% and a contamination of 0,4%. The genome contains 6122 protein-coding genes of which 3564 (similar to 60%) have known functions. The genome and phylogeny indicate that Pseudomonas sp. RGM2144 is a new species in the Pseudomonas genus, with few virulence factors, plasmids, and genes associated with antimicrobial resistance, suggesting a non-pathogenic bacterium with protective potential. In addition, the genome encodes for 11 secondary metabolite biosynthetic gene clusters that could be involved in the inhibition of F. psychrophilum. We suggest that Pseudomonas sp. RGM2144 may be applied as a probiotic in salmonid fish farming.