What are bacteriophages?
Bacteriophages — or phages for short — are viruses that infect bacteria. With an estimated 1031 particles on Earth, they are the most abundant biological entities on the planet, outnumbering bacteria ten to one. Wherever bacteria thrive — in the ocean, soil, the human gut, and hospital wards — phages are there too, relentlessly preying on them.
Phages work by latching onto a bacterial cell, injecting their genetic material, and hijacking the cell's own machinery to replicate. The bacterium either bursts open releasing new phage particles, or the phage quietly integrates into the bacterial chromosome — becoming a prophage — lying dormant for thousands of generations. These hidden passengers are far from inert: prophage genes can rewire their host's biology, conferring virulence, antibiotic tolerance, and the ability to colonise entirely new environments.
In an era of rising antibiotic resistance, phages are also gaining attention as therapeutics — precision biological agents capable of targeting pathogens that drugs can no longer reach. Understanding the ecology and evolution of phage–bacteria interactions sits at the heart of our research.
