Sustained release of beneficial microorganisms for corals from alginate beads under marine conditions

Aim Coral reefs support more than one-third of the global marine biodiversity, but global stressors have negatively impacted their health by disrupting fragile microbial partnerships, leading to widespread mass bleaching events. To address this issue, the use of beneficial microorganisms for coral (BMCs) has been shown to enhance coral resilience. In this study, we evaluated the potential of alginate beads as a delivery method for BMCs underwater. Methods and Results BMCs were encapsulated in alginate beads and incubated in artificial seawater at 26°C and 32°C. Microbial viability within the beads and bacterial release were monitored over a three-week period. Cell viability and sustained release rate were maintained throughout the experiment, with viable cell release averaging 106 cells h−1 per 50 mL flask by the third week at both temperatures. Co-encapsulation of multiple BMC strains resulted in changes in bacterial dynamics. Conclusions These findings demonstrate that alginate beads can provide sustained delivery of viable BMCs under marine conditions and represent a promising platform for probiotic-based coral restoration strategies.