Delgadillo-Ordonez, N. | Search bioRxiv

bioRxiv2025

Probiotic and postbiotic treatment in situ during a marine heat wave improves coral health and promotes specific metabolic and microbiome changes

Microbial therapies are emerging as promising tools for coral protection against heat stress, yet such application was not tested in situ. We tested two coral-derived probiotic consortia and their heat-killed counterparts (postbiotics) on bleaching Acropora cf. valida in the Red Sea during a marine heatwave. Over 15 days, both live and one of the heat-killed treatments maintained photosynthetic efficiency (Fv/Fm), whereas placebo-treated corals exhibited significant thermal stress-induced decline. 16S rRNA gene sequencing profiling showed enrichment of putatively beneficial genera (e.g., Terasakiispira spp., Pseudoalteromonas spp.), and untargeted metabolomics resolved treatment-specific metabolic signatures that differed among consortia and between live and inactivated formulations. These molecular fingerprints illuminate specific underlying protective mechanisms and host-microbiome interactions under heat stress. Together, our results position microbial therapies (probiotics and specific postbiotics) as field-validated, mechanism-informed interventions capable of minimizing impacts on corals during real-world thermal extremes and provide design cues for scalable deployment.

microbiology↗

bioRxiv2024

Bacterial inoculation manipulates the coral epigenome

Environmental shifts can cause epigenetic modifications in corals, which are associated with changes in gene expression and physiology, though it remains unclear if associated bacteria can also induce such changes. Here, we inoculated nubbins of the coral Pocillopora verrucosa with an opportunistic pathogen, Vibrio coralliilyticus, and/or a coral probiotic, Cobetia sp., and subjected the nubbins to heat stress. We show that pathogen exposure led to distinct DNA methylation changes compared to the control, probiotic, and co-inoculation groups. We also demonstrate that DNA methylation correlates with coral gene expression and highlight genes altered by pathogen inoculation that showed similar responses in their expression and methylation. Notably, the coral probiotic was able to mitigate specific epigenetic changes, which correlated with increased stress resilience and higher coral survival rates. Thus, bacterial-induced changes to the coral epigenome may instigate long-term changes in host resilience.

molecular biology↗