Myxococcus xanthus: Cultivation, Motility, and Development

Abstract

This chapter presents a description of methods for cultivation of Myxococcus xanthus laboratory strains, as well as specific protocols for analysis of motility and development. Here the authors attempt to cover representative techniques, and to mention variations only occasionally. In nature, communities of M. xanthus reside in the soil on decaying plant material or herbivore dung and obtain nutrients by secreting digestive enzymes (such as proteases and lysozyme) to digest macromolecules from prey microorganisms or decaying organic matter. Initiation of the developmental program resulting in fruiting body formation requires (i) nutrient limitation, (ii) a solid surface, and (iii) sufficient population density. Fruiting body morphology and timing are greatly dependent on the medium surface. Therefore, solid media for development should be prepared the day before and plates should be cured (prewarmed) by incubating the plates with lids cracked open at least 20 min at 32oC just before use. M. xanthus powers its movement over solid surfaces by using two genetically distinct motility systems. Social (S) motility—the coordinated movement of cells in large groups—predominates on soft and moist surfaces and is directly mediated by the extension and retraction of polar type IV pili. Adventurous (A) motility—the movement of single isolated cells—predominates on harder and drier surfaces and has been proposed to be based on either a jet engine-like extrusion of carbohydrate slime, a twisting or inching-like motion on the part of the M. xanthus cell, or intracellular motors pushing against dynamic focal adhesion points within the cell.