A dynamical system model for simulating myxobacteria life cycle

Myxobacteria (Myxococcus xanthus) are social bacteria whose entire life cycle is pervaded by cell-cell interactions. When starved, myxobacteria stop swarming outward the colony and organize themselves to undergo develop- mental stages, which culminate in the formation of three-dimensional fruiting body. Elongated, motile cells inside the fruiting body differentiate into round, non-motile, resistant spores.;In this dissertation, a bioenergetic-based dynamical system model is developed to simulate the life cycle of myxobacteria. The key feature in this model is the automatic transition from the swarming stage to the stage of fruiting body formation. This is done through the coupling of the bioenergetics, called Dynamic Energy Budget (DEB), and a logistic equation that is used to keep track of the C-signaling level. DEB controls cell growth and division during the swarming stage, and inhibits them during starvation and fruiting body development. The internal energy reserve in the DEB model, together with the food density parameter, function as the trigger mechanism for this transition. The number of C-signal molecules found by solving the logistic equation controls the switching between stages in the fruiting body formation and individually regulates a cell to sporulate once the maximum threshold is reached.;Our derivation of the scaling laws and the concept of superindividual enable us to simulate a large number of cells, and thus minimize the computational complexity. The simulation of the swarming stage with a large number of cells allows us to quantify global patterns for different strains of myxobacteria by computing their order parameter.;We also show that the use of DEB not only captures the dynamics of the cells at the individual level, but it also provides the link to the population level. In particular, we analyze the connection between bacterial cell size and population growth rate. Finally, we propose a model for signaling mechanism during fruiting body development using DEB as constraints. This model potentially links the processes at the individual and sub-organismal levels.