We eat food to keep ourselves happy and healthy. While the foods we eat are degraded in our gut, it’s actually little microbes that do most of the work to break down our food. Many many microbes. It is well known that our diet controls our health. But until recently, we have not appreciated the intermediate step that relies on microbes in our gut, and their influence on our health. What if our gut microbes are just as important for human health as the food we eat? The so-called gut microbiome, the unique community of microbes living in our digestive tract that influences how we break down food, is the quickly evolving research area that our guest is interested in. Michael Sieler is a 3rd year Ph.D. student in the Microbiology Department and is interested in better understanding how environmental factors, like rising temperatures and pathogens to name just a few, influence our gut microbiome and thus our health.

There are hundreds of  different microbial species living in human guts. These microbes work together to support human health by helping us digest our food and fight off pathogenic microbes. Because humans eat a multitude of diets, it can be tricky to figure out how human health is influenced by our gut microbes if the things we eat are not consistent. Instead of forcing humans to undergo rigorous eating and environmental trials – that may even be unethical given how much we’d need to control a human life – researchers like Michael use different organisms that are similar to humans to help understand some of the fundamental drivers of health. While you may be thinking of mice trials to see how toxic a substance is, or if we’ve successfully created a non-hallucinogenic version of psilocybin for therapeutic purposes, mice still have plenty of limitations. 

Instead of using mice to run experiments, researchers are increasingly using zebrafish because they’re well studied, easy to grow and maintain, fast to reproduce, and 70% of their genes overlap with human genes so we can generally use these little fish as models of larger humans. For example, we’ve interviewed previous guests like Grace Deitzler researching how the gut microbiome can influence anxiety disorders and the connections to autism spectrum disorder. We’ve also interviewed Sarah Alto who researched how different levels of oxygen and carbon dioxide are connected to stress responses. Finally, Delia Shelton is actively researching how cadmium, a toxic heavy metal, is influencing behavioral patterns. You can imagine these studies would be tricky to perform on humans, that’s why all of these researchers use zebrafish as their model organism. 

Michael’s work focuses on how environmental factors impact our gut microbiome to influence our health. For example, exposure to antibiotics or pathogens can dramatically affect the microbes living in our guts, but so can our diet. Surprisingly, unlike other model organisms such as mice, zebrafish are not fed a consistent diet across research studies and facilities. Given the importance of the gut microbiome to digest food and support our health, inconsistent use of diets in zebrafish microbiome studies could lead to inconsistency in study results. It’s like trying to compare race times for a five-mile race, except some people get to use cars and bikes and unicycles. Without a standard way to compare people, how comparable are the race results? Michael’s current work seeks to address this conundrum by feeding zebrafish one of three commonly used research diets and comparing their microbiomes. He finds that type of diet has an overwhelming effect on their gut microbiome, and these effects may overwhelm the effects of other environmental factors, like pathogen exposure.

What does this mean for the mountain of research built on zebrafish? We’ll answer that, and so much more with our guest Michael Sieler. We’ll also discuss his non-traditional route to graduate school, his love of travel, a side project using a tamagotchi-style video game to teach students about fish health, and how a year in the Guatemalan countryside helped him rethink his relationship to food and how he could have a greater impact in our world. Tune in live on Sunday at 7pm PT on 88.7FM, or check out the podcast if you missed the interview.