Associate Professor Jeremy Barr reflects on the journey of T-series bacteriophages – the microscopic marvels that revolutionised our understanding of microbiology
Associate Professor Jeremy Barr
When Associate Professor Jeremy Barr began his graduate studies, he never imagined that a failed experiment with raw sewage would set the course for his ground-breaking research.
“I started by collecting hundreds of litres of sewage to study how microorganisms formed dense biofilms in wastewater treatment systems,” says Barr.
But when his bioreactor failed, it wasn’t just a setback.
It was a revelation.
Using electron microscopy and proteomics, Barr discovered that bacteriophages – viruses that infect bacteria – were responsible for the collapse of his experiment. This chance discovery marked the beginning of his fascination with phages, particularly the T-series bacteriophages, which have shaped the field of microbiology for decades.
The T-series bacteriophages, introduced in the 1940s by Max Delbrück, were designed as reductionist models for studying life.
“Delbrück’s vision was to use a small, manageable system to uncover fundamental biological principles,” Barr explains.
These seven phages, which exclusively infect the bacterium Escherichia coli, became the foundation for countless scientific breakthroughs, including discoveries in molecular genetics and biotechnology.
Delbrück’s approach was transformative. By enforcing a standard set of tools—the T-series phages and E. coli—he united researchers from diverse fields and created a model system that remains unparalleled in its impact.
“These phages weren’t just tools; they were the keys to unlocking some of life’s biggest mysteries,” says Barr.
Fast-forward to Barr’s postdoctoral years, when he found himself searching for a model phage to study their role in mucosal surfaces. In a dusty freezer drawer, he discovered ØT4, one of Delbrück’s T-series gems.
“It was a random choice that turned out to be pure luck,” Barr recalls. ØT4 helped Barr and his team establish the “bacteriophage adherence to mucus” model, showing how phages can reduce bacterial colonisation on mucosal surfaces.
Barr’s journey with T-series phages continued as he inherited a 50-year-old stock of these viruses.
Genetic comparisons between the old and new strains revealed remarkable stability, affirming the enduring value of these models.
“Despite some genetic drift, their core functionality remains intact. It’s a testament to Delbrück’s foresight,” says Barr.
While T-series phages have been indispensable, Barr emphasises the need to move beyond these traditional models.
“We’ve only scratched the surface of phage diversity,” he notes. With trillions of viruses in nature, researchers are exploring new ecosystems and microbial interactions.
“The next generation of scientists will make discoveries that redefine what we know about phages,” says Barr.
Still, the T-series phages remain close to Barr’s heart. “These tiny giants have shaped the past, but their legacy will guide the future”.
Read more at Nature Microbiology.
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