Abstract
Abstract
We investigate the dynamics of the spread of the infection due to a phage-
λ
during the range expansion of an
E coli
colony. We find a rich panoply of spatio-temporal dynamics at large colony-level length scales, arising due to the interplay of mechanical forces, growth and viral infection dynamics at smaller cellular length scales. Strikingly, the phages “surf” the front of the growing bacterial colony by hitchhiking on
E coli
that are advected due to the growth of bacteria in the colony, resulting in an anisotropic spread of the phages. We identify microscopic processes – of the phage release during lysis (occurring on short millisecond timescales at length scales close to that of a single bacterium) and local nematic lignment of the rod-like
E coli
bacteria (occurring on timescales comparable to the bacterial growth rate and the length scales of a few bacterial cells) – that enhance the advective effects driving the hitchhiking behavior. Combining our experiments with a mathematical model, we explain the multiple spatio-temporal dynamical regimes – from the coexistence of uninfected bacteria, resistant (lysogenic) cells and phages, to fixed points where the entire population turns resistant or remains uninfected. Our work broaches a new frontier in the investigation of eco-evolutionary processes arising from the mechanical and ecological forces due to the interactions between viruses and their hosts.