Spooky season is upon us, and what better time than now to talk about everyone’s favorite creepy critter, bats. While bats are often misunderstood or vilified, they’re also important to ecosystems and are uniquely poised to teach us more about how animals and microbes interact.
For Bat Week, we chatted with Melissa Ingala, a Peter Buck postdoctoral fellow at the Smithsonian’s National Museum of Natural History, about her research into the myriad bacteria living inside of bats’ guts. Ingala is working to characterize what bacteria associate with the winged mammals and to expand the museum’s collections in the process.
How did you get interested in bats?
I always loved nature, but I never had a specific fascination with bats even though I had some encounters. When I was a kid bats would sometimes come into the house, and we’d catch them in a plastic Tupperware container and put them outside.
In college, I had to do a research rotation as part of my degree program. I ended up working with my academic advisor who was studying White Nose Syndrome, a deadly fungal disease in bats. I approached it with an open mind, because I needed the research credits. But I didn't expect that I would fall in love with the animals themselves. It was kind of a circuitous route to get to them, but now I can't think of doing anything else.
What is the microbiome, and how do you study it in bats specifically?
Throughout history, our primary preoccupation with bacteria has been that they can cause diseases for us. But, over the last couple of decades, we've grown this appreciation that our bodies are colonized by trillions of bacteria, viruses and protists, and these things that live in and on us are actually not typically harmful. In fact, they're really useful for us. That complicated community of [microbes] is called the microbiome, and the most diverse of those communities is in our gut. Our gut microbiome is basically like a rainforest in terms of the sheer number and density of species that live there. They’re really important for supporting our health and well-being, and other mammals have their own gut microbiomes too.
My research is primarily documenting what bacteria live inside of bats, and then also trying to understand what those bacteria do functionally. For example, fruit bats live on a diet that nutritionally would be like us only ever eating Hershey bars. There's a lot of sugar in fruit, but not a lot of protein, fat or other things that bats need to survive. One of the questions that I have is, how are their bacteria potentially contributing to their nutritional needs? Maybe they're supplying proteins, or fats or other things that are missing from the diet.
What does your research look like from the field to the lab?
Most of my fieldwork happens in Central and South America because the tropics are where bat diversity tends to be highest. We catch bats at night in nets, then wait for the bat to poop. Then I take those fecal pellets and put them in liquid nitrogen to preserve the bacteria inside and ship them back here to the U.S. where we can do the laboratory work.
In the lab, we use genetic tools to “barcode” the bacteria [in the poop]. Just like when you scan a barcode on an item at the grocery store, we take a genetic scan of all the bacteria in that sample and compare it to a database that tells us what those bacteria are. In that way we can get the full community picture of what bacteria live inside of the bats.
It’s funny, I’ve gotten to the point where I can pretty much identify a bat by the way its poop looks. The shades of the poop can actually be quite beautiful. For example, the fruit eating bats eat a lot of plant material, so the poop makes these brilliant green colors.
How does your work intersect with the museum’s collections?
There are two ways. Whenever we collect fecal samples from bats, sometimes we'll take [bat specimens], too. This is a pretty uncommon practice — most people who do microbiome work just collect a fecal sample and send it on its merry way. But what I prefer to do, when possible, is to take an actual specimen home for the museum, because then when research starts to develop later on, you can actually link it back to the animal that it came from.
The other thing is a work in progress. The Smithsonian is working on trying to get a handle on something called environmental DNA. You can get DNA from any material, like water or air, to the point where if a tiger walked past you, and you swab the air, you may be able to pick up tiger DNA. We have this really critical question as a natural history museum: we're so focused on specimens, how do we deal with these samples that aren't true specimens, but are still biologically relevant and may be important in the future? Microbiomes fit into that category. I serve on a committee at the museum where we're trying to hash out how the Smithsonian can be the leader in those type of collections, because almost no natural history museum does that kind of stuff yet.
Can we learn anything about human microbiomes by researching bat microbiomes?
A lot of the bacteria in fruit bats are probably adapted to breaking down sugars into other types of molecules. Those kinds of bacteria can be similar, if not the same, as bacteria that are involved in things like diabetes, obesity or other sugar processing disorders that humans have. But because so much of bacterial biodiversity is not well characterized, we don't even know what the full scope of those bacteria are, or what they do.
Bats are sometimes misunderstood and can be scapegoats for disease outbreaks like COVID-19. Is there anything that you wish people knew about them?
I think a lot of folks have heard the spiel that bats are important for pest suppression, but I don't think people really understand the global scale or economic scale of the services they provide. In the Midwestern U.S., where corn is a major crop, bats provide billions of dollars a year in pest control services by feeding on corn earworm moth larvae. Other bats in Thailand do the same thing over rice paddies. In tropical areas of the world, there are tons of bat species that are major pollinators of crops that are important to humans — perhaps the most famous example of that is the agave used to make tequila.
For all of the bad press that bats have been getting because of COVID-19, I think it's important for people to understand that this is not the bats’ fault. If humans were not destroying their habitats so that they must come into closer proximity to us and to our livestock, these kinds of zoonotic diseases would probably spill over into humans much less frequently.
This interview has been edited for length and clarity.
Meet a SI-entist: The Smithsonian is so much more than its world-renowned exhibits and artifacts. It is a hub of scientific exploration for hundreds of researchers from around the world. Once a month, we’ll introduce you to a Smithsonian Institution scientist (or SI-entist) and the fascinating work they do behind the scenes at the National Museum of Natural History.