Engineering microbiomes to enhance macroalgal health, biomass yield, and carbon sequestration

Macroalgae farming not only holds significant economic value but also contributes substantially to carbon sequestration, and therefore has gained intensified attention globally under climate change scenarios. However, its sustainability is increasingly threatened by anthropogenic and environmental changes. The health and resilience of macroalgae are intrinsically linked to their associated microbiomes, offering an untapped opportunity to enhance macroalgal farming through microbiome manipulation. In this review, we have summarized the current understanding of macroalgal microbiomes, highlighting critically underexplored microbial components, such as overlooked taxa, host specificity, and the environmental factors influencing microbiome composition, which hinder the development of effective microbiome engineering strategies. We critically evaluate existing microbiome manipulation approaches and their applications in enhancing macroalgal growth, resilience, carbon fixation, and biomass yield and assess their potential for improving macroalgal carbon sequestration. Finally, we propose a holistic framework that integrates multi-omics and metabolic modeling, microbial functional and environmental compatibility, high-throughput rapid isolation, and in vivo validation to bridge critical knowledge gaps and unlock the full potential of macroalgal microbiome engineering for sustainable, large-scale macroalgal farming.