Deoxyribonucleic Acid Synthesis During Exponential Growth and Microcyst Formation in Myxococcus xanthus

Abstract

Myxococcus xanthus in exponential phase with a generation time of 270 min contained a period of 50 mm during which deoxyribonucleic acid (DNA) synthesis did not take place. After induction of microcysts by the glycerol technique, the DNA content increased 19%. Autoradiographic experiments demonstrated that the DNA made after glycerol induction was not evenly distributed among the micro-cysts. The distribution of grains per microcyst fits the following model of chromosome replication: in exponential phase, each daughter cell receives two chromosomes which are replicated sequentially during 80% of the division cycle; after microcyst induction, no chromosomes are initiated. Mathematical formulas were derived which predict the kinetics and discrete probability of distribution for several chromosome models.