Repression of alkaline phosphatase in Salmonella typhimurium carrying a phoA+ phoR- episome from Escherichia coli.

Salmonella typhimurium does not produce alkaline phosphatase (nor beta-galactosidase). Nevertheless, it has the function of the phoR+ regulatory gene but lacks the function of the lacI+ regulatory gene. Several periplasmic proteins are derepressed when cells of S. typhimurium are starved for inorganic phosphate. The role of phoR is discussed.