Unlocking Targeted Underwater Delivery of Coral Probiotics

Abstract

The rapid global decline of coral reefs has intensified the need for innovative conservation strategies, including microbial therapies to enhance coral health and resilience. A major limitation, however, is the lack of effective delivery systems for administering Beneficial Microorganisms for Corals (BMCs). In this study, we present natural, biodegradable systems for the underwater delivery of probiotic bacteria to corals. Three customized alginate-based delivery formats (beads, hydrogels, and filaments) were developed and loaded with the probiotic Pseudoalteromonas peptidolytica. The materials were loaded with the bacterium at an average concentration of 10^(4) CFU/g of dry polymer and engineered to sink underwater while keeping their structural integrity over time. In vitro assays showed controlled release kinetics, with encapsulated probiotics remaining viable and capable of replication. In vivo experiments compared syringe-based inoculation with the application of alginate beads, hydrogels, and filaments to corals. Microbiome analyses performed before and after inoculation confirmed successful probiotic colonization following deployment of the alginate-based delivery systems. Relative abundance of the probiotic genus Pseudoalteromonas increased markedly in treated corals, reaching 11.5 % after 48 h with alginate beads, 12.7 % after 48 h with hydrogels, and 12.6 % after 24 h with filaments. Furthermore, the degradation mechanisms of the three delivery systems were investigated. As the first biomaterial-based underwater delivery systems specifically engineered for coral probiotics, these alginate-based materials provide a promising foundation for advancing microbial therapies in both controlled aquaria and natural reef environments.

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BibTeX RIS

BibTeX

@misc{facchinelli2026unlocking,
  title = {{Unlocking Targeted Underwater Delivery of Coral Probiotics}},
  author = {M. P. Facchinelli and M. Contardi and J. Caldwell and F. Fiorentini and I. Ghizzi and V. Calabretta and L. Ceseracciu and T. Pomili and V. Isa and G. Corigliano and C. Rinaldi and V. Scribano and E. Bellini and L. Ravelli and S. Lavorano and I. Gandolfi and P. Galli and S. Montano and A. Athanassiou},
  howpublished = {bioRxiv},
  year = {2026},
  month = nov,
  doi = {10.64898/2026.11.04.764210},
  url = {https://www.biorxiv.org/content/10.64898/2026.11.04.764210v1},
  note = {CC BY},
}

RIS

TY  - UNPB
TI  - Unlocking Targeted Underwater Delivery of Coral Probiotics
AU  - M. P. Facchinelli
AU  - M. Contardi
AU  - J. Caldwell
AU  - F. Fiorentini
AU  - I. Ghizzi
AU  - V. Calabretta
AU  - L. Ceseracciu
AU  - T. Pomili
AU  - V. Isa
AU  - G. Corigliano
AU  - C. Rinaldi
AU  - V. Scribano
AU  - E. Bellini
AU  - L. Ravelli
AU  - S. Lavorano
AU  - I. Gandolfi
AU  - P. Galli
AU  - S. Montano
AU  - A. Athanassiou
PY  - 2026
DA  - 2026/11/04
PB  - bioRxiv
DO  - 10.64898/2026.11.04.764210
UR  - https://www.biorxiv.org/content/10.64898/2026.11.04.764210v1
AB  - The rapid global decline of coral reefs has intensified the need for innovative conservation strategies, including microbial therapies to enhance coral health and resilience. A major limitation, however, is the lack of effective delivery systems for administering Beneficial Microorganisms for Corals (BMCs). In this study, we present natural, biodegradable systems for the underwater delivery of probiotic bacteria to corals. Three customized alginate-based delivery formats (beads, hydrogels, and filaments) were developed and loaded with the probiotic Pseudoalteromonas peptidolytica. The materials were loaded with the bacterium at an average concentration of 10^(4) CFU/g of dry polymer and engineered to sink underwater while keeping their structural integrity over time. In vitro assays showed controlled release kinetics, with encapsulated probiotics remaining viable and capable of replication. In vivo experiments compared syringe-based inoculation with the application of alginate beads, hydrogels, and filaments to corals. Microbiome analyses performed before and after inoculation confirmed successful probiotic colonization following deployment of the alginate-based delivery systems. Relative abundance of the probiotic genus Pseudoalteromonas increased markedly in treated corals, reaching 11.5 % after 48 h with alginate beads, 12.7 % after 48 h with hydrogels, and 12.6 % after 24 h with filaments. Furthermore, the degradation mechanisms of the three delivery systems were investigated. As the first biomaterial-based underwater delivery systems specifically engineered for coral probiotics, these alginate-based materials provide a promising foundation for advancing microbial therapies in both controlled aquaria and natural reef environments.
ER  -

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