Construction of ryhB2 mutants of the food-borne pathogen Salmonella enterica serovar Typhimurium

We constructed deletion mutants of the ryhB2 gene of Salmonella enterica serovar Typhimurium strain ATCC14028s using two different genetic strategies.The B858 mutant was obtained by transduction of the ryhB2 mutation present in the Salmonella enterica serovar Typhimurium LT2 strain into strain ATCC14028s using phage P22.The H195 mutant was constructed by recombination of a mutated PCR fragment into the genome of the ATCC14028s strain.Since the two ryhB2 mutants had different phenotypes, their genome sequences were compared. This allowed us to identify a mutation present in the LT2 strain which was cotransduced with the ryhB2 mutation in the B858 mutant. This mutation is probably responsible for the different phenotype of the two mutants.