November 2, 2022 - Podcast

Episode 319 — How bacteria affect coral reefs

About half of the world’s total coral reef cover has been lost since the 1950s due to many causes, including climate change, disease outbreaks, destructive fishing practices and pollution. Increases in ocean temperature caused by climate change correlate with increased disease incidence and outbreaks in coral.

A research team led by Indiana University's Julia van Kessel, an associate professor of biology, was awarded a National Science Foundation grant to study the coral reef ecosystem. Specifically, the researchers hope to gain a better understanding of how to help maintain coral reefs by learning how the coral pathogen Vibrio coralliilyticus interacts with its environment in a coral host.

This bacterium is a primary and opportunistic pathogen that infects numerous species of coral and causes bleaching and tissue loss, as well as potentially exacerbating the effects of other diseases.

The van Kessel research lab specializes in quorum sensing, a cell-to-cell communication signaling process used by some bacteria.

The researchers hypothesize that quorum sensing signaling and temperature variations control virulence genes of the bacterium that are critical to its ability to infect coral. They will investigate how temperature, other bacteria, and communications between Vibrio coralliilyticus populations alter the ability of the pathogens to cause coral diseases.

The researchers will identify and examine virulence factors controlled by primary systems that respond to the environment, as well as examine how each of these systems influences coral colonization and disease progression in a live coral infection model and its microbiome.

With guidance from Blake Ushijima, an assistant professor at University of North Carolina Wilmington, and his graduate students, IU is building a live coral facility for the researchers to study. The facility will include a 100-gallon tank to store artificial sea water made in the lab, as well as several tanks for conducting experiments.

As their work evolves, the researchers plan to showcase connections between bacterial pathogens and coral disease by using a live coral exhibit and live bacterial cultures in public outreach exhibits.

Van Kessel says that in addition to corals, the Vibrio bacteria are pathogenic to fish, shellfish, and urchins. This means that discoveries from her work will contribute to a fundamental understanding of Vibrio pathogenesis and extend to other research programs.