The remarkable ability of migratory animals to navigate and remember routes can be attributed to sensitivity not only to the Earth’s magnetic fields, but also perhaps to interaction with the magnetic bacteria living inside them.
The relationship between these magnetic bacteria and the animals they live in is not yet fully understood, but UCF Department of Biology Assistant Professor Robert Fitak recently compiled a database of animal DNA that contains hundreds of millions of sequences showing the presence of different types of magnetic bacteria. use as a tool in his quest to learn more.
The database signals a step forward in his research, building on previous hypotheses and analyzes published in 2020 in collaboration with colleagues in the UK and Israel.
In 2021, Fitak continued to search databases to categorize which animals might host magnetic bacteria and if there were prevailing patterns.
“The first study we did was to look at existing data sets and summarize where we found these bacteria in different animals,” he says. “We searched about 50,000 previous scientific studies. Now we’ve actually expanded it to study a global database of genetic information and we’ve been able to summarize where these bacteria are based on trillions of genetic sequences.”
The database was published earlier this year in Data in briefand borrows information from the publicly available Sequence Read Archive from the National Center for Biotechnology Information.
Fitak focused on organizing DNA sequences from different animal species that correspond to known magnetic bacteria to help him and other researchers narrow their efforts to investigate the environmental and ecological roles of magnetic bacteria or to identify potential host animals.
Inner compass?
Fitak and his colleagues use the refined data to identify potential host organisms for the magnetic bacteria, providing greater context for examining the roles they may play in animals—for example, for navigation.
“Ultimately, if we better understand how animals move, it will be useful for the conservation of endangered or protected species,” says Fitak. “If we know where they move and how, it can help us make more accurate management decisions.”
He is interested in whether the magnetic bacteria reside in areas inside the animal that they can sense, such as parts of the nervous system. Fitak thinks they could serve as a navigational aid for animals or provide additional support to creatures such as birds or sea turtles that already use the Earth’s magnetic field to navigate long distances.
“It’s almost like a microbial compass, and we’re studying how it might work,” says Fitak. “We think animals already use the Earth’s magnetic field as a compass.”
He also says that another potential benefit is that scientists can study how animals perceive magnetic fields and potentially mimic how they are used in various applications, such as drug delivery.
However, there is no conclusive evidence that these animals use magnetic bacteria to navigate or not, Fitak says.
“The big takeaway we have so far from our research is that we don’t yet know that these bacteria are sensing bacteria for the animal, but we have evidence that they live in these animals,” he says. “But we’ve learned that we can use genetic markers that are signatures of the bacteria that make the magnets, and we’ve identified those genetic signatures of those bacteria inside different animals — including humans.”
These types of bacteria often live in sediments or mud where there isn’t much oxygen, Fitak says. They assemble microscopic and magnetized iron “chains” that help them move, he says.
It’s not certain how organisms end up with these bacteria inside, but it’s theorized to possibly be through absorption or consumption, Fitak says.
“To date, our results across projects show that these magnetic bacteria appear to be a regular part of many species of microbiomes,” he says. “We hope that our future work will show whether they are just acquired by chance from the environment, a functional component of magnetic sensing for the host animal, or for some other unknown reason.”
Focus on sea turtles
Fitak and his team of student researchers are focused on examining samples from green and loggerhead sea turtles to further study magnetic bacteria.
“Sea turtles are kind of a model of animal navigation,” he says. “We tested our hypotheses on sea turtles because they travel very precisely to very specific locations.”
Focusing on sea turtles was a natural next step because they are known to have magnetic bacteria and rely on Earth’s magnetic field to migrate, Fitak says. UCF’s Marine Turtle Research Group was also involved in obtaining turtle samples, he says.
Julianna Martin, Ph.D. student working with Fitak helped analyze and collect nearly 150 sea turtle specimens.
“I work in the lab extracting DNA from samples and using genomics to identify what bacteria are in the samples and which ones we’re looking for that make the magnets,” he says. “I could not have collected the samples without the help of the UCF Marine Turtle Research Group.” It was a team effort.”
Martin and scientists at UCF’s Marine Turtle Research Group are gently sampling tears using soft swabs from nesting females—who go into a near-trance state while laying eggs—and hatchlings in the Indian River Lagoon.
Turtles produce large gooey tears when they’re on land to keep their eyes moist, and they take about 30 seconds to collect, Martin says.
“We started with the tear ducts because they are connected to nerves that are potentially connected to the animals’ magnetic sense,” he says. “It looks biologically there, and it’s easy to collect sea turtle tears.”
Martin says she’s pleased with their progress so far, but hopes their momentum will propel their research to definitive conclusions.
“This research was really exciting,” he says. “No one has looked for them specifically in sea turtles.” I wonder where they came from and what kinds of magnet-making bacteria each species of sea turtle has. It’s a long way off, but for now we’re working on the description: ‘are they there?’ and ‘where do they come from?'”
The potential to share the unique discovery of magnetic bacteria helping animals navigate is truly amazing, says Fitak.
“What was exciting was just being able to tell people that there are bacteria in this world that make magnets,” he says. “People are amazed, and it would be incredible if animals were actually using these magnetic bacteria to navigate.”
Fitak encourages researchers interested in studying magnetic bacteria to examine the data he has compiled.
All sea turtle samples were collected under UCF MTRG Protected Species Permits (MTP-231, MTP-171, and NMFS 26268)
Credentials of the researcher
Fitak is an assistant professor in UCF’s Department of Biology in the College of Sciences. He received his doctorate in genetics from the University of Arizona and his bachelor’s degree in molecular genetics from The Ohio State University. Before joining UCF in 2019, he worked as a postdoctoral researcher at the Institute for Population Genetics in Vienna, Austria, and at Duke University. He is a member of the UCF Genomics and Bioinformatics Research Cluster.
Martin is a PhD in biology at UCF. student who aspires to continue her genetics research at university. She received her bachelor’s degree from St. Mary’s College of Maryland and worked at the American Genome Center at the Uniformed Services University.