Assessment of multiple probiotic strains that protect Montipora capitata coral from infection by Vibrio coralliilyticus.
Coral disease outbreaks threaten reef ecosystems, often leading to widespread mortality and declines in coral cover. Outbreaks of tissue loss diseases like acute Montipora white syndrome (aMWS) have impacted coral populations that include the Hawaiian rice coral (Montipora capitata). Multiple strains of Vibrio coralliilyticus are known pathogens, and strain OCN008 has been demonstrated as an etiological agent of aMWS in Hawai'i. Recent work has demonstrated that probiotic bacterial strains can be used to directly treat or prevent transmission (prophylaxis) of coral diseases. Based on their production of zones of inhibition and isolation from disease-resistant corals, Pseudoalteromonas ardens R96, Pseudoalteromonas obscura P94, strain Y97 (the genomic similarity to Pseudoalteromonas piscicida is presented), Pseudoalteromonas umbrosa B95, and Vibrio tetraodonis subsp. pristinus OCN044 were assessed for their ability to impair V. coralliilyticus OCN008 infection of M. capitata during laboratory infection trials. Individual inoculation of each of the five aforementioned strains on M. capitata fragments for 48 h prior to V. coralliilyticus OCN008 inoculation resulted in up to a 93.75% reduction in mortality. These results indicate that strains of Pseudoalteromonas and Vibrio can act as prophylactics to prevent M. capitata mortality from V. coralliilyticus OCN008 infection and provide tools to improve disease resilience for Pacific corals.IMPORTANCECoral disease outbreaks are a growing threat to the continued health of coral reefs, which are already vulnerable ecosystems. Strains of the bacterium Vibrio coralliilyticus are known to infect various coral species worldwide, predominantly causing tissue loss and death of the coral animal. Previous research has indicated that constituents from healthy coral microbiomes can act as probiotics to treat or prevent coral infections, and the discovery of effective probiotics is important in the effort to further develop mitigation tools for disease outbreaks. This work provides a demonstration of probiotic species that can protect coral from tissue loss infections by a strain of Vibrio coralliilyticus and is an example of probiotics developed for coral species in Hawai'i. This work provides new tools for probiotic-based coral protection and evidence for this research as a viable avenue to protect coral in their native environments.