Halfway across the world, off the colorful coasts of Australia, surgeonfish like Dory “just keep swimming” into the nets of Cornell microbiology experts. Known for their brightly colored exteriors, surgeonfish contain unique gastrointestinal bacteria known as Epulopiscium spp. that play a key role in the digestive processes of surgeonfish and can provide insight into human microbiology.
Alejandro Schmieder ’21, biological sciences, has been researching Epulopiscium morphotypes in relation to surgeonfish migration patterns and has been working under the guidance of Prof. Esther Angert, microbiology.
“The bacteria are really fascinating to us because they’re the second largest known bacteria in the world,” Schmieder said. Epulopiscium can reach sizes of 0.6 mm or greater – visible to the naked eye.
According to Schmieder, Epulopiscium spp. are not just one species – they have an astounding level of morphological diversity, and have thousands of copies of chromosomes, making them extremely polyploid. This means that Epulopiscium cells have to be classified based on size, shape and method of reproduction in order to distinguish them under the microscope.
Schmieder’s research focuses on the different Epulopiscium morphotypes and how they relate to surgeonfish migration patterns. Aligning morphotypes and reproductive strategies with migrating populations of surgeonfish can reveal how these factors impact the symbiotic relationship of Epulopiscium with its host.
According to Schmieder, Angert herself and other collaborators travel to Australia or Hawaii to capture surgeonfish and extract bacteria from the gut.
“I think our lab is unique in that we focus so heavily on these bacteria,” Schmieder said.
When the samples arrive in Ithaca, Schmieder examines the gut bacteria under a microscope and assesses the abundance of Epulopiscium cells and their morphotypes. He then isolates DNA after lysing the cells, conducts PCR amplification and sequences the genes of interest.
According to Schmieder, the complicated ethics of studying the human microbiome often direct microbiologists towards studying simpler model organisms, such as Epulopiscium.
“Our system can explain some of the complexities in host-microbe systems,” Schmieder said.
“The idea that a community we can’t even see has such an impact on our lives really struck me.”
Schmieder hopes to use his research with Epulopiscium to write an honors thesis and continue studying microbiology in graduate school.
“Especially now with all the research and advances in gut microbiology, we’re learning how what we eat influences who we are, but also [how] our microbiome … influences everything about us,” Schmieder said.