Reexamination of the role of autolysis in the development of Myxococcus xanthus.

It has been widely reported that 80 to 90% of the cell population undergoes autolysis during sporulation in Myxococcus xanthus. A re-evaluation of the techniques used to measure autolysis in M. xanthus showed that the methods previously used to draw this conclusion are subject to artifacts, which result in a substantial underestimation of the number of cells present during development. We found that at least 80% of the cells that enter development survive throughout fruiting body formation. The cell loss that did occur appeared to be gradual over a period of at least 7 days. Our results suggest that autolysis is not an obligate stage in the development of M. xanthus. The data also showed that sporulating cells pass through a prespore stage in which they become osmotically and physically fragile and therefore difficult to harvest intact. The fragility was correlated with the change from a rod to a spherical shape. As the prespores differentiated into refractile spores, they lost fragility and became amenable to harvesting by standard protocols.