Bacterial competition: surviving and thriving in the microbial jungle

Abstract

As has been studied extensively for macroorganisms, competition between and within microbial species constitutes a crucial facet of microbial life in the environment. Individuals in a population of a single bacterial species will be in competition with each other when nutrients are limiting. If the ecological opportunity arises (such as when populations are grown in a spatially structured environment, providing multiple niches), intraspecies competition can lead to selection for the diversification of a bacterial population. Under some conditions, cooperation among individuals in a bacterial population can facilitate competition between groups. However, cooperation can be vulnerable to cheating. Bacteria engage in diverse active competitive strategies. These include: accumulating and storing specific nutrients, thereby depriving potential competitors; blocking access to favourable habitats (such as binding sites on a surface) or forcing the dispersal of competitors; motility, especially when directed (chemotaxis); producing antimicrobial toxins; and interfering with competitors' signalling. Microbial systems should be exploited further for testing ecological theories of competition. Additionally, new technologies should aid in moving the study of bacterial competition from the test tube to the natural habitats of microorganisms.