Phages and bacteria coexist in virtually any ecosystem, and remnants of their interactions are found in most bacterial genomes. Starting with phage-bacterial interactions, I will describe the use of standard predator-prey equations to quantify how phages may boost bacterial diversity, or how different bacteria may use even a single phage type to maintain this diversity. Subsequently, by use of a simple bet-hedging scenario I discuss the pros and cons for virulent versus temperate phage strategies. Finally I introduce an epidemic model for phages spreading on a bacterial lawn, thereby again emphasizing the advantages of temperate phages as well as the peculiarities of the lysogenic decision network in phage lambda.
 
References:
J. O. Haerter et al., "Phage and bacteria support mutual diversity in a narrowing staircase of coexistence", The ISME Journal 8 (2014)
S. Maslov et al., "Well-temperate phage: optimal bet-hedging against local environmental collapses", Scientific reports 5 (2015)
K Sneppen et al., "Restriction modification systems as engines of diversity", Frontiers in microbiology 6 (2015)
 

Dr. Kim Sneppen is a full professor at the Niels Bohr Institute and a Member of the Danish Royal Academy of Sciences. He obtained his PhD in Theoretical Nuclear Physics in 1989. His research focuses on complex and biological systems using methods from statistical physics. Topics he worked on include self organization and emergent patterns, transcription and translation processes, epigenetics, phage biology, microbial diversity, dynamics, epidemics and cross-immunization. He has published about 190 articles in internationally peer-reviewed journals with about 11,000 citations, and authored two books. In the past 9 years, he has been the leader of the Center for Models of Life, financed by a generous center of excellence grant from the Danish National Research Council. He serves as the Divisional Associated Editor of the Physical Review Letters since August 2014.