There is a lot that we don’t know about the microbial world, but we do know that it is rich and diverse and full of surprises. Nobody imagined that viruses could be as large as bacteria until somebody did and started looking for them. Before long, they found giant viruses.
But although there are indeed bacteria smaller than giant viruses, they are not that much smaller. The tiny uncultivated bacteria found in groundwater in western Colorado have a diameter of about 0.3 µm[1] , whereas the largest viruses appear to have diameters of about 0.4 µm[2] .
Large virus. By Chantal Abergel – Own work, CC BY-SA 3.0, File:Megavirus.jpg – Wikimedia Commons
Small bacterium. Black scale bar is 100 nm (0.1 µm). From First Detailed Microscopy Evidence of Bacteria at the Lower Size Limit of Life | Berkeley Lab
Beside the size difficulty, there is also an architectural barrier. Bacteria metabolize; metabolism requires water and a liquid interior space; this space can be invaded and co-opted by infecting agents such as viruses.
Viruses, by definition, don’t metabolize except inside a host. They have little free unbound water and no interior space to speak of. A bacterium could “eat” its way in I suppose, but this would be like saying you are “infecting” a watermelon if you eat your way inside.
There is no biological “law” that says a bacterium cannot infect a virus, and it’s not crazy to think that it could happen. But for now there is no evidence that it does.
Footnotes
[1] Diverse uncultivated ultra-small bacterial cells in groundwater
1 thought on “Can a bacteria infect a virus?”