Probiotics reshape the coral microbiome in situ without affecting the surrounding environment. 16S amplicon sequencing of Red Sea corals to assess the application of probiotics

The use of Beneficial Microorganisms for Corals (BMCs), or coral probiotics, has been validated in laboratory trials as a microbial therapy to enhance coral health and resilience to climate change and other impacts. Here, we present the first in situ application of a BMC consortium. Colonies of Pocillopora verrucosa from a central Red Sea reef were repeatedly inoculated over a period of three months and fragments were collected at four time points to assess bacterial community, algal photosynthetic capacity, and coral holobiont thermal thresholds. Microbiome analyses via 16S rRNA gene-based amplicon sequencing revealed a significant effect of the probiotic treatment on coral-associated bacteria, but not on the microbiomes of the surrounding seawater or sediments.