Biology

Dr. Sandeep Krishna
NCBS, Bangalore

Virulent bacteriophage and their bacterial hosts represent an unusual sort of predator-prey system where hundreds of new predators are born each time a single prey is eaten. It is puzzling how, despite the apparent effectiveness of the phage predators, they manage to avoid driving their bacterial prey to extinction. Bacteria, of course, have developed multiple mechanisms to defend against phage. I'll talk about some mathematical models which suggest that restriction-modification systems, which are at best a weak and temporary defence against bacteriophage, can enhance long-term coexistence of multiple bacterial strains. The models suggest that this diversity can be as large as the burst size of the phage but no larger - a curious correspondence between a number at the level of species and a biophysical parameter that characterises individual phage.