The remarkable ability of migratory animals to navigate and remember their routes may be attributed to a sensitivity not only to the Earth’s magnetic fields, but perhaps to an interaction with the magnetic bacteria living inside them.
The relationship between these magnetic bacteria and the animals in which they reside 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 various types of magnetic bacteria to use as a tool in his quest to learn more.
The database marks a step forward in his research and builds on previous hypotheses and analyses published in 2020 in collaboration with colleagues in the UK and Israel.
In 2021, Fitak continued to scour databases to categorize which animals might harbor magnetic bacteria and whether there are any widespread patterns.
“The first study we did was to look at existing datasets and summarize where we found this bacteria in different animals,” he says. “We looked at about 50,000 previous scientific studies. Now we’ve extended that study to a global database of genetic information and we’ve been able to summarize where these bacteria are based on billions of genetic sequences.”
The database was published earlier this year in Data in briefand it borrows information from the publicly available sequence reading archive of the National Center for Biotechnology Information.
Fitak focused on organizing DNA sequences from different animal species that match known magnetic bacteria to help him and other researchers refine their efforts in examining the environmental and ecological roles of magnetic bacteria or to identify potential animal hosts.
An internal compass?
Fitak and his colleagues are using the refined data to identify potential host organisms for magnetic bacteria and to provide broader context for examining the roles they may play in animals, such as navigation.
“Ultimately, if we understand better how animals move, it will be useful for the conservation of threatened or protected species,” Fitak says. “If we know where they are going to move and how, it can help us make more accurate management decisions.”
He wants to know whether magnetic bacteria reside in regions of the animal so they can be detected, such as in parts of the nervous system. Fitak thinks they could serve as a navigational aid for animals or provide an extra boost to creatures like birds or sea turtles that already use the Earth’s magnetic field to move long distances.
“It’s almost like a microbial compass, and we’re studying how it might work,” Fitak says. “We think animals already use the Earth’s magnetic field as a compass.”
He adds that another potential benefit is that scientists can study how animals detect 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 move around, Fitak says.
“The bottom line is that we don’t know yet whether these bacteria detect the bacteria that are in 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 of bacteria that make magnets, and we’ve identified these genetic signatures of these bacteria inside a variety of animals, including humans.”
These types of bacteria often live in sediment or sludge where there isn’t much oxygen, Fitak says. They assemble microscopic, magnetized iron “chains” to make it easier to move around, he says.
It’s not clear exactly how organisms end up with these bacteria inside them, but it’s thought to happen perhaps through absorption or consumption, Fitak says.
“To date, the results of our projects show that these magnetic bacteria appear to be a regular component of the microbiome of many species,” he says. “We hope that our future work will show whether they are simply picked up by chance from the environment, whether they are a functional component of magnetic sensing for a host animal, or whether they are due to some other unknown reason.”
Focus on sea turtles
Fitak and his team of student researchers are focusing on examining samples from green and loggerhead turtles to study magnetic bacteria in more detail.
“Sea turtles are a kind of model of animal navigation,” he explains. “We tested our hypotheses on sea turtles because they move to very specific locations with great precision.”
It was a natural fit to focus on sea turtles because they are known to have magnetic bacteria and rely on the Earth’s magnetic field to migrate, Fitak says. UCF’s sea turtle research group was also instrumental in obtaining turtle samples, he says.
Julianna Martin, a doctoral student working with Fitak, helped analyze and collect nearly 150 sea turtle samples.
“I work in the lab to extract DNA from the samples and use genomics to identify the bacteria in the samples and which ones make the magnets we’re looking for,” she says. “I couldn’t have collected the samples without the help of the UCF Sea Turtle Research Group. It’s a team effort.”
Martin and scientists from UCF’s Sea Turtle Research Group carefully collect tear samples using soft swabs from nesting females — which enter a trance-like state when they lay their eggs — and juveniles in the Indian River Lagoon.
Turtles produce large, sticky tears when they’re on land to keep their eyes moist, and collecting them takes about 30 seconds, Martin says.
“We started with the tear ducts because they are associated with nerves that are potentially associated with the animals’ magnetic sense,” she explains. “From a biological perspective, it makes sense to look at them, 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 toward more definitive conclusions.
“This research is really exciting,” she says. “No one was looking for them specifically in sea turtles. I would like to know where they come from and what species of magnet-producing bacteria each species of sea turtle has. That’s a long way off, but right now we’re working on describing ‘are they there?’ and ‘where do they come from?’”
The potential to share the unique discovery of magnetic bacteria helping animals navigate is truly wonderful, Fitak says.
“What’s exciting is being able to tell people that there are bacteria in this world that make magnets,” he says. “People are amazed, and it would be amazing if animals actually used these magnetic bacteria to navigate.”
Fitak encourages researchers interested in studying magnetic bacteria to explore the data he has compiled.
All sea turtle samples were collected under UCF MTRG Protected Species Permits (MTP-231, MTP-171, and NMFS 26268)
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Fitak is an assistant professor in the Department of Biology in the UCF College of Science. He received his PhD 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 of Population Genetics in Vienna, Austria, and at Duke University. He is a member of the UCF Genomics and Bioinformatics Research Center.
Martin is a UCF PhD student in biology who plans to continue her research in genetics at the university. She earned her bachelor’s degree from St. Mary’s College of Maryland and worked at the American Genome Center at the Uniformed Services University.