Coexistence of phage and bacteria on the boundary of self-organized refuges.
Bacteriophage are voracious predators of bacteria and a major determinant in shaping bacterial life strategies. Many phage species are virulent, meaning that infection leads to certain death of the host and immediate release of a large batch of phage progeny. Despite this apparent voraciousness, bacteria have stably coexisted with virulent phages for eons. Here, using individual-based stochastic spatial models, we study the conditions for achieving coexistence on the edge between two habitats, one of which is a bacterial refuge with conditions hostile to phage whereas the other is phage friendly. We show how bacterial density-dependent, or quorum-sensing, mechanisms such as the formation of biofilm can produce such refuges and edges in a self-organized manner. Coexistence on these edges exhibits the following properties, all of which are observed in real phage-bacteria ecosystems but difficult to achieve together in nonspatial ecosystem models: (i) highly efficient virulent phage with relatively long lifetimes, high infection rates and large burst sizes; (ii) large, stable, and high-density populations of phage and bacteria; (iii) a fast turnover of both phage and bacteria; and (iv) stability over evolutionary timescales despite imbalances in the rates of phage vs. bacterial evolution.
Center for Models of Life, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark. heilmann@nbi.dk
Silja
S
Heilmann
Kim
K
Sneppen
Sandeep
S
Krishna
D001419:Bacteria / Q000821:virology*; D018407:Bacterial Physiological Phenomena; D001435:Bacteriophages / Q000502:physiology*; D005075:Biological Evolution; D017753:Ecosystem; D008954:Models, Biological; D053038:Quorum Sensing / Q000502:physiology