In any given environment, millions of microbial species compete with each other for resources while locked in an endless state of warfare with viruses trying to infect them
While scientists have studied how bacteria move towards food using a chemical radar known as chemotaxis, they have only watched single species swim in isolated environments over distances of only a few centimeters. In a new study published May 20, 2026 in Nature Communications, Flinders University PhD graduates Dr. Susie Grigson and Dr. Abbey Hutton were part of a Flinders-based research team that examined the migration of microbial communities over long distances – and learned surprising outcomes. The open-access article is titled “Co-Migration of Hundreds of Microbial Species Over Metres Drives Selection and Promotes Non-Motile Hitchhikers.” The researchers examined sewage-derived microbial communities in a tube system that allowed their movement to be tracked, analyzing both their taxonomic composition (identifying exactly which species were present) and their gene profiles (what the bacteria were actively doing) as they migrated over several meters across a full week. “Essentially, we created a new experimental system for looking at bacterial migration over long distances and time scales – by using garden tubing from a hardware store,” explains Grigson.
The researchers identified that a subset of the original sewage-based community broke away and self-organized into migrating bands that were visible to the naked eye.
These bands proved that bacteria can migrate over vast distances – not as solitary swimmers, but in diverse, coordinated communities that also bring along viruses and “hitchhiking” microbes that cannot even swim on their own.
The researchers discovered that these bands actually increase in speed as they travel. As migration progresses, the harsh journey acts as a natural filter that selects bacteria which are the strongest swimmers and most efficient at accessing nutrients to fuel the microbial community’s forward momentum.
Through mimicking the complexity of natural microbial environments, the new study shows more than 500 bacterial species that co-migrate over meter-scale distances. Along the way, this community constantly reshaped itself. While dominant bacteria frequently turned over and changed, many rare bacteria managed to persist and survive the journey.
“We aimed to determine whether a single species would outcompete all others during migration and whether viruses would persist alongside the migrating community or remain behind,” says Grigson.
“Because our setup allowed us to watch the migration unfold in real-time, we could finally study microbial movement as a massive community event rather than just isolated cells swimming alone.”
The team filled the garden tubing with a nutrient-rich gel, nutrients and a color-changing dye to visually follow the path of bacteria. Then, by using DNA sequencing, they could read the genetic signatures of the migrating community, allowing them to map which microbes led the charge and which were left behind.
“Our findings show that bacteria aren’t just swimming to outrun the viruses that infect them,” says Grigson. “Instead, they travel together to hunt for food, bringing along viruses and ‘hitchhiking’ microbes that can’t even swim on their own.”
Sustaining this microbial diversity during migration has profound real-world implications.
In a medical context, it provides a new framework for understanding how potentially dangerous, non-swimming pathogens could spread through the human body, or through hospitals and water systems, by hitching a ride with highly mobile communities.
Environmentally, the research reveals how ecosystems maintain their biodiversity and resilience, allowing rare but crucial microbes to colonize new habitats, support agricultural soil health, and drive wastewater treatment through complex teamwork rather than acting alone.
Additional authors include Jessica Carlson-Jones, James Paterson, Sarah Giles, Clarice Harker, Amelia Grigson, Amy Annells, Michael Roach, Peter Speck, Robert Edwards, and James Mitchell.