The remarkable ability of migratory animals to navigate and remember routes can be attributed to a sensitivity not only to the Earth’s magnetic fields, but perhaps to an interaction with the magnetic bacteria that live within them.
The relationship between these magnetic bacteria and the animals they inhabit is not yet fully understood, but UCF Biology Department assistant professor Robert Fitak recently compiled a database of animal DNA containing hundreds of millions of sequences that indicate the presence of different types of magnetic bacteria. to use as a tool in his pursuit of learning more.
The database signals a step forward in his research and builds on previous hypotheses and analyzes published in 2020 in collaboration with colleagues in the UK and Israel.
In 2021, Fitak continued to examine the databases to categorize which animals may harbor magnetic bacteria and whether there are widespread patterns.
“The first study we did was to look at existing data sets and summarize where we found this bacterium in different animals,” he says. “We searched about 50,000 previous scientific studies. Now, we’ve actually extended that to study a worldwide database of genetic information, and we’ve been able to summarize where these bacteria are located based on trillions of genetic sequences.
The database was released 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 all animal species that match known magnetic bacteria to help him and other researchers narrow their efforts to examining the environmental and ecological roles of magnetic bacteria or to identify potential host animals.
An inner compass?
Fitak and his colleagues are using the refined data to identify potential host organisms for the magnetic bacteria and provide a larger context for examining the roles they may play in animals – such as for navigation.
“Ultimately, if we have a better understanding of how animals navigate, it will be useful for the conservation of endangered or protected species,” says Fitak. “If we know where they’re going to move and how, that can help us make more accurate management decisions.”
He is interested in seeing if magnetic bacteria inhabit areas inside an animal so they can sense them, such as part of the nervous system. Fitak thinks they could serve as a navigational aid for animals or provide an extra boost for creatures like 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 another potential benefit is that scientists could study how animals sense magnetic fields and potentially mimic how they are used in a variety of applications, such as drug distribution.
However, there is no conclusive evidence that these animals are using the magnetic bacteria to navigate or not, says Fitak.
“The big takeaway we have so far from our research is that we still don’t know that these bacteria are sensing the bacteria for the animal, but we have evidence that they live in these animals,” he says. “But what we’ve learned is that we can use genetic tags that are signatures for magnet-producing bacteria, and we’ve identified these genetic signatures of these bacteria within different animals — including humans.”
These types of bacteria often live in sediments or mud where there isn’t much oxygen, Fitak says. They collect microscopic, magnetized iron “chains” to help propel themselves, he says.
It’s uncertain how organisms end up with these bacteria inside them, but it’s theorized perhaps through absorption or consumption, Fitak says.
“To date, our results across projects indicate that these magnetic bacteria appear to be a regular component of the microbiomes of many species,” he says. “We hope that our future work will show whether they are picked up by chance from the environment, a functional component of magnetic sensitivity for a host animal, or for some other unknown reason.”
Stopping at the sea turtles
Fitak and his team of student researchers have focused on examining samples from green sea turtles and shrimp to further study magnetic bacteria.
“Sea turtles are kind of a model of animal navigation,” he says. “We tested our hypotheses in sea turtles as they travel to very specific locations with great precision.”
Focusing on sea turtles was a natural next step since they are known to harbor magnetic bacteria and rely on the Earth’s magnetic field to migrate, Fitak says. UCF’s Sea Turtle Research Group has also been instrumental in sampling the turtles, he says.
Julianna Martin, a Ph.D. student working with Fitak, has helped analyze and collect nearly 150 sea turtle samples.
“I work in the lab to extract DNA from samples and use genomics to identify which bacteria are in the samples and which are the ones producing the magnets we’re looking for,” she says. “I could not have collected the samples without the help of the UCF Sea Turtle Research Group. It’s been a team effort.”
Martin and scientists with the UCF Sea Turtle Research Group gently collect tear samples with soft swabs from nesting females — who enter an almost trance-like state when they lay eggs — and juveniles in the Indian River Lagoon .
Turtles produce large tears when they’re on the ground to keep their eyes moist, and it takes about 30 seconds to collect them, Martin says.
“We started with the tear ducts because they are connected to nerves that are potentially related to the animal’s magnetic sense,” she says. “It makes biological sense to look there, and it’s easy to collect sea turtle tears.”
Martin says she’s pleased with their progress so far, but hopes their momentum pushes their research toward more definitive conclusions.
“This research has been really exciting,” she says. “Nobody had looked for them specifically in sea turtles. I’m interested in knowing where they came from and what kind of magnet-making bacteria each type of sea turtle has. It’s a long way off, but right now we’re working to describe, ‘are they there?’ and ‘where do they come from?’
The potential to share the unique discovery of magnetic bacteria that help animals navigate is truly amazing, says Fitak.
“What’s been exciting is just being able to tell people that there are bacteria that exist in this world that make magnets,” he says. “People are amazed, and it would be incredible if animals really used these magnetic bacteria to navigate.”
Fitak encourages researchers interested in the study of magnetic bacteria to explore the data he compiled.
All sea turtle samples were collected under UCF MTRG Protected Species Permits (MTP-231, MTP-171, and NMFS 26268)
Researcher credentials
Fitak is an assistant professor in the UCF Department of Biology in the College of Science. He received his PhD in genetics from the University of Arizona and his bachelor’s in molecular genetics from 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 UCF’s Genomics and Bioinformatics research group.
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. Mary of Maryland and worked at the US Genome Center at the Uniformed Services University.