envB mutations confer UV-sensitivity to Salmonella typhimurium and UV-resistance to Escherichia coli

An envB mutation isolated in Salmonella typhimurium LT2 was transferred by conjugation to Escherichia coli K-12. The mutation produced the same alterations in E. coli as in S. typhimurium concerning cell shape, sensitivity to drugs, autolysis, and fermentation of carbohydrates. However, although the mutation conferred sensitivity to UV irradiation in Salmonella, in E. coli it behaved as a genuine envB mutation producing resistance to UV inactivation. The fact that the mutation produced opposite effects in the survival of UV-irradiated S. typhimurium and E. coli discloses an intriguing difference between these closely related species.