Spontaneous zygogenesis (Z-mating) in mecillinam-rounded bacteria.
In Escherichia coli the process of spontaneous zygogenesis (Z-mating), i.e. complete genetic mixing in the absence of a conjugative plasmid, was investigated further. Spontaneous-zygogenesis-promoting (Szp+) cells displayed strong clustering with each other and with ordinary F* cells in the optimal cell density range for Z-mating. When induced to rounding by the drug mecillinam, they aggregated into large, dense, stainable syncytium-like cells leaving giant ghosts upon lysis. In Z-mating mixtures of mecillinam-treated cells, these giant cells co-purified with mating products as other cells died. Giant cells recovering from mecillinam treatment yielded monstrous, branching forms, whereas non-Szp+ coccal cells reverted to rods in one step, and some 29% of the colonies formed were identified as deriving from entities possessing two distinct genomes. Z-mating was examined between E. coli and a distantly related Serratia marcescens strain. In the presence of calcium, mecillinam-rounded cells of a stable non-complementing diploid hybrid with the E. coli phenotype segregated normally dividing cells of the Serratia form.
Laboratory of Phage-Typing and Bacterial Genetics, Pasteur Institute of Brussels, Rue Engeland, 642, 1180 Brussels, Belgium, jpgratia@yahoo.fr
Jean-Pierre
JP
Gratia
D000560:Amdinocillin / Q000494:pharmacology*; D002876:Chromosomes, Bacterial / Q000235:genetics; D003227:Conjugation, Genetic / Q000235:genetics / Q000502:physiology*; D004171:Diploidy; D048168:Escherichia coli K12 / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D011995:Recombination, Genetic / Q000235:genetics*; D012706:Serratia marcescens / Q000187:drug effects / Q000235:genetics / Q000502:physiology*
D000560:Amdinocillin