Application of phage lambda technology to Salmonella typhimurium. Construction of a lambda-sensitive Salmonella strain.

We have previously constructed a novel strain of S. typhimurium carrying the E. coli lamB gene and shown that this strain adsorbs phage lambda and, for example, can be used for transposon mutagenesis with lambda vectors. In this study, we show that this strain can support the lytic growth of phage lambda nin derivatives, but not growth of wild-type lambda. However, lysogenization with lambda nin does not occur. Using this strain as starting material we took the construction one step further by introducing the E. coli nusA gene in a multicopy plasmid to this strain. We could show that this new Salmonella derivative can support both the lytic and lysogenic mode of growth of several different lambda derivatives. Using the same approach it should be possible to construct lambda-sensitive derivatives of other enteric bacteria thus rendering them more amenable to in vivo genetic manipulation.