The <i>Roseobacter</i> -Group Bacterium <i>Phaeobacter</i> as a Safe Probiotic Solution for Aquaculture

Abstract

Phaeobacter inhibens has been assessed as a probiotic bacterium for application in aquaculture. Studies addressing the efficacy and safety indicate that <i>P. inhibens</i> maintains its 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 <i>P. inhibens</i> produces antibacterial and algicidal compounds, no study has so far found a virulent phenotype of <i>P. inhibens</i> cells against higher organisms. Additionally, an <i>in silico</i> search for antibiotic resistance genes using published genomes of representative strains did not raise concerns regarding the risk for antimicrobial resistance. <i>P. inhibens</i> occurs naturally in aquaculture systems, supporting its safe usage in this environment. In conclusion, at the current state of knowledge, <i>P. inhibens</i> is a "safe-to-use" organism.