The development of the flora of the alimentary tract in young animals

Abstract

An ultraviolet-induced mutant has been isolated from the double auxotroph of Bacillus subtilis (bearing the linked mutations try2 and his2). This mutant has the property of yielding unstable transformants which, in the case of transformation to prototrophy, can be recognized by reduced colony size on minimal agar. Unstable transformant clones usually become stabilized early during the development of the clone (within 12 generations). Analyses of genotypes emerging from such clones on stabilization indicate that in some of these clones the exogenote is transmitted linearly; its integrity is sufficiently preserved that it can participate in two independent recombination events in two different cells. Genetic markers on the exogenote are expressed in situations where genetic integration has nlot occurred.