The effect of osmotic shocking upon Bacillus subtilis transformation

Abstract

Osmotic shocking of competent Bacillus subtilis reduced transformability by 80–90% through depressing the uptake of radioactive DNA. The supernatant solution from competent cultures restored both transformation and DNA uptake. A factor, which was inactivated by proteolytic enzymes and which was released into the supernatant solution concomitant with the development of maximum competence, was responsible for restoration of transformability. This factor was both heat and pH labile and was produced only by competent strains. While the shock fluid did not restore transformability to shocked ceils, it increased competence 20-fold in a low-transforming strain. The supernatant solution from competent cultures also increased transformability of the low-competence strain. Thus it appears that at least two factors are involved in competence restoration.