The Roseobacter-group bacterium Phaeobacter as safe probiotic solution for aquaculture

Phaeobacter inhibens has been assessed as a probiotic bacterium for application in aquaculture. Studies addressing the efficacy and safety indicate that P. inhibens maintains it antagonistic activity against pathogenic vibrios in aquaculture live cultures (live feed and fish egg/larvae), while having no or a positive effect on the host organisms, and a minor impact on the host microbiomes. While producing antibacterial and algicidal compounds, no study has so far found a virulent phenotype of P. inhibens cells against higher organisms. Additionally, an in silico search for antibiotic resistance genes using published genomes of representative strains did not raise concern regarding the risk for antimicrobial resistance. P. inhibens occurs naturally in aquaculture systems supporting its safe usage in this environment. Concluding, at the current state of knowledge, P. inhibens is a “safe-to-use” organism.