Isolation of Salmonella typhimurium Tn5 mutants defective for survival on egg shell surface using transposon footprinting

The objective of this study was to screen the genome of Salmonella typhimurium for genes potentially required for survival on egg shell surfaces using a novel transposon footprinting method based on a previously developed Tn5 mutagenesis technique. Since the amplified DNA fragment length should usually be unique for each mutant, the polymerase chain reaction products separated on an agarose gel generate a transposon footprint with each band in the footprint representing the corresponding Tn5 mutant. By comparing the footprints from the pools of S. typhimurium Tn5 mutants before and after inoculation on egg shell surfaces, Tn5 mutants not recovered after selection were rapidly identified for potential isolation and genetic analysis.