Abstract
SUMMARY: Zygote formation between strains of Escherichia coli K-12 is dependent on a supply of free energy made available by the oxidation of carbohydrate via the Krebs cycle reactions. The simultaneous addition of glucose and a dicarboxylic acid of the tricarboxylic acid cycle, or an immediate precursor, to mating cells markedly stimulates the number of zygotes formed. Reagents known to inhibit reactions of the Krebs cycle inhibit zygote formation. Evidence was obtained that synthesis of protein or either pentose or deoxypentose nucleic acid was not necessary for zygote formation.