Antagonistic interactions among coral-associated bacteria

Area of Science:

• Marine microbiology
• Coral reef ecology
• Symbiotic relationships

Background:

• Coral holobionts comprise coral animals, symbiotic algae (zooxanthellae), and diverse microbes.
• The ecological roles and contributions of coral-associated microbes to holobiont health are largely unknown.
• Understanding microbial interactions is crucial for coral health and disease resistance.

Purpose of the Study:

• To investigate bacteria-bacteria antagonism within the microbial communities of the scleractinian coral Montastrea annularis.
• To assess the impact of temperature on microbial antagonism.
• To identify potential roles of microbial antagonism in coral pathogenesis and disease resistance.

Main Methods:

• Collected 67 bacterial isolates from Montastrea annularis.
• Utilized Burkholder agar diffusion assays to test for antagonistic activity between isolates.
• Performed assays at two temperatures (25°C and 31°C) to evaluate temperature effects.

Main Results:

• A majority of bacterial isolates exhibited antagonism (69.6% at 25°C, 52.2% at 31°C).
• Gamma-proteobacteria, including Vibrionales and Alteromonadales, were particularly antagonistic.
• Elevated temperatures generally decreased antagonism, though effects were complex.
• Some isolates inhibited the growth of the coral pathogen Vibrio shiloi (11.6% at 25°C).

Conclusions:

• Bacterial antagonism is a significant structuring force in coral-associated microbial communities.
• Microbial antagonism may play a dual role in coral health, contributing to both pathogenesis and disease resistance.
• The findings highlight the importance of microbial interactions in maintaining coral holobiont function.