Host-controlled Restriction Mutants of Salmonella typhimurium

SUMMARY Forty-eight independent restriction-deficient mutations of Salmonella typhimurium lt 2 were isolated by using selective and non-selective methods. With phage P 22 it was shown that some mutations affected the restriction capacity only, while others affected both restriction and modification. The host-restriction of S. typhimurium decreased the recovery of F-lac + infected cells and decreased the yield of recombinants in bacterial mating and in phage P 22-mediated transduction.