Gene tandem-mediated selection of coliphage lambda-receptive Agrobacterium, Pseudomonas, and Rhizobium strains

Agrobacterium, Pseudomonas, and Rhizobium spp. have been made receptive to coliphage λ . To achieve this, recombinant (pTROY) plasmids carrying a constitutive Escherichia coli lamB gene encoding the λ receptor and expressed from an insertion sequence 3 (IS3) promoter were introduced into various bacteria. Because the wild-type λ receptor was not expressed in these bacteria, a procedure called the lamB gene tandem protocol was used to select lamB alleles that expressed the λ receptor. This gene tandem protocol may have general use in adapting genes with nonselectable traits to different organisms. Agrobacterium, Pseudomonas, and Rhizobium strains carrying pTROY41613, which encoded a gene tandem-selected λ receptor, could be quantitatively transduced with λ -packaged cosmids. With the ability to confer λ receptivity on organisms, phage λ now becomes a general DNA delivery agent.