The Formation and Germination of Microcysts in Myxococcus xanthus

SUMMARY: An investigation has been made of the sequence of morphological events involved in the processes of microcyst formation and germination in the fruiting myxobacterium Myxococcus xanthus. By using time-lapse photo-micrographs and phase-contrast microscopy of living cells, microcyst formation is shown to involve a shortening and thickening of the entire vegetative cell with a subsequent increase of refractility. Germination is preceded by the casting off of a sheath followed by the gradual elongation and loss of refractility of the cell. Vegetative rods will readily form spheroplasts when exposed to a variety of conditions including sulphydryl compounds. The necessity for distinguishing between spheroplasts and microcysts is pointed out.