A Possible Mechanism of Repressing Cheating Mutants in Myxobacteria

Abstract. The formation of fruiting bodies by myxobacteria colonies involves altruistic suicide by many individual bacteria and is thus vulnerable to exploitation by cheating mutants. We report results of simulations that show how in a structured environment with patchy distribution of cheating mutants the wild type might persist. This work was inspired by experiments on myxobacteria Myxococcus xanthus reported in [1]. Under adverse environmental conditions individuals in an M. xanthus colony aggregate densely and form a raised “fruiting body ” that consists of a stalk and spores. During this process, many cells commit suicide in order to form the stalk. This “altruistic suicide ” enables spore formation by other cells. When conditions become favorable again, the spores will be released and may start a new colony. Velicer et al. studied in [1] some mutant strains that were deficient in their ability to form fruiting bodies and had lower motility but higher growth rates than wild-type bacteria. When mixed with wild-type bacteria, these mutan