Temperature-induced behavioral switches in a bacterial coral pathogen

Area of Science:

• Marine microbiology
• Coral disease ecology
• Climate change impacts on marine ecosystems

Background:

• Elevated seawater temperatures are linked to increased coral disease outbreaks.
• Microbial motility and chemotaxis are crucial for coral pathogen colonization and infection.
• The impact of warming on these specific microbial behaviors remains largely unexplored.

Purpose of the Study:

• To investigate the effect of increasing water temperatures on the motility and host-seeking behaviors of the coral pathogen Vibrio coralliilyticus.
• To quantify changes in chemotaxis and chemokinesis of Vibrio coralliilyticus under simulated heat-stress conditions.
• To understand how climate change-driven warming may enhance the efficiency of marine bacterial pathogens.

Main Methods:

• Field-based heat-stress manipulations were combined with laboratory-based microfluidic observations.
• The swimming behavior of thousands of individual Vibrio coralliilyticus cells was recorded at various temperatures (23°C and 30°C).
• Chemotactic and chemokinetic abilities toward coral mucus (from Pocillopora damicornis) were measured.

Main Results:

• At temperatures ≥23°C, Vibrio coralliilyticus exhibited over 60% increased chemotactic ability toward coral mucus.
• At 30°C, the pathogen's chemokinetic ability increased by over 57%, enhancing acceleration in mucus-rich conditions.
• Increasing temperatures significantly augment the motile behaviors and host-seeking efficiency of this marine bacterial pathogen.

Conclusions:

• Increasing seawater temperatures induce behavioral changes in Vibrio coralliilyticus that enhance its ability to locate and infect coral hosts.
• Warming conditions, consistent with climate change scenarios, can significantly boost the pathogenic potential of marine microbes.
• This study highlights the multifarious impacts of ocean warming on microbial-host interactions and coral health.