Saving Coral Reefs by Using a Sea Anemone as a Laboratory Model for Studying Host-Microbe Interactions



​Coral reefs are among the most diverse ecosystems in the world and are home to a large variety of marine organisms. In addition to their ecological importance, coral reefs have significant economic, aesthetic and medicinal value, including the compounds for biomedical research and therapies. At present, natural and anthropogenic stresses threaten the health of coral reefs worldwide. Global climate change is driving the rise in ocean temperatures, leading to coral bleaching and death. Finding the means for corals to adapt to and survive in higher temperatures requires a more thorough understanding of their physiology as a whole—the corals themselves, and all the microorganisms they associate with.

At California State University, Chico, Dr. Cawa Tran, assistant professor of biological sciences, and her research team of master’s and undergraduate students look toward the potential for bacteria to help animals increase their heat tolerance. For the ease of laboratory manipulation, they experiment with a well-established model organism, a sea anemone called Exaiptasia pallida (commonly referred to as “Aiptasia”), that is related to corals. Both are symbiotic cnidarians (a group that also contains jellyfish) that will expel algae in response to stress.

Jamie Sydnor, the most senior graduate student in the Tran laboratory, has examined the community of bacteria that Aiptasia usually associates with (its microbiome) and how that community stochastically changes when the animal experiences heat stress. To better understand how these bacteria are initially integrated into the animal, Dr. Tran and her research team are collaborating with Dr. Joseph Greene, professor of sustainable manufacturing and mechanical engineering at Chico State, and a team of four mechanical engineering undergraduates (Thomas Cunningham, Emily Williams, Alize Hall and Sultan Alharbi). Together, they are designing a novel microfluidics chamber to enclose live anemones with flowing seawater under a microscope that will allow video recording of fluorescently labeled bacteria entering and establishing residence within these anemones in a process known as colonization.

The long-term goal of the Tran laboratory is to identify specific bacteria that can tolerate higher temperatures and, in turn, enable their animal host to endure these higher temperatures and survive in the face of global climate change. These beneficial microbes may serve as marine probiotics to help corals. Caution must be taken before manipulating corals and their microbiomes in nature; therefore, by testing heat-tolerant capabilities in a laboratory model like Aiptasia, Tran and her students can use this information to explore the potential of improving coral health with the aid of heat-resistant bacteria. This experimental manipulation of microbes, communities and their hosts is referred to as microbiome engineering, which has been used in both agricultural practices and human medicine. The Tran laboratory is attempting to harness the power of microbiome engineering to enable more thermotolerant animals. This research has inspired new training for Chico State students in biology and engineering to use modern biotechnological tools to understand animal-microbe interactions and help save coral reefs.