Exploring seaweed-associated microbiota as emerging probiotic candidates for aquaculture

The rapid expansion of aquaculture has intensified the need for sustainable strategies to improve productivity and disease control, particularly amid growing concerns about antibiotic use. Probiotics have emerged as a promising alternative; however, conventional sources, primarily derived from aquatic animal guts, often exhibit inconsistent performance under field conditions. In this context, seaweed-associated microbiota represents a relatively underexplored but potentially valuable source of probiotic candidates. This review synthesizes current knowledge on the diversity and functional traits of seaweed-associated bacteria and evaluates their relevance to probiotic application in aquaculture. Key traits discussed include stress tolerance, antimicrobial activity, competitive exclusion and colonization ability, enzymatic capabilities, and the production of bioactive compounds linked to growth promotion and immunomodulation. Evidence indicates that these bacteria possess adaptive features suited to dynamic marine environments and exhibit multiple functions consistent with established probiotic mechanisms. However, most studies remain trait-specific, with limited in vivo validation and insufficient integration of functional assessments. Consequently, there is a need for more comprehensive and systematic evaluation of these microorganisms. Overall, seaweed-associated bacteria present a promising yet underutilized resource, and further research is essential to fully establish their role as next-generation probiotics in sustainable aquaculture systems.