1987

Harkki, Anu

In this study the host range of phage A has been extended to Salmonella typhimurium. All tested derivatives of A could both produce plaques on this strain at frequencies comparable to Escherichia coli and Iysogenize this strain. This was achieved by including the E. coli genes lamB (receptor for 1) and nusA (a host factor of transcription complex) into S. typhimurium. To facilitate strain constructions a vector expressing both of these E. coli genes was constructed. The feasibility of this vector was studied in S. typhimurium by isolating in vivo gene fusions to an outer membrane porin gene with phage A vehicles. An expression vector for introduction of,' receptor function into other enteric bacteria was constructed. The ability of this vector to express lamB was verified in several enteric bacteria: E. coli, S. typhimurium, Vibrio cholerae and Erwinia carotovora. The function of LamB as a A receptor was determined in V. cholerae by studying the ability of these new V. cholerae derivatives to support cosmid transduction with 1 vehicles. In conclusion, it has been shown that the host range of A can be extended and furthermore that the ability of A to serve as a vehicle for transfer of genetic elements can be introduced via /lamBEC into variety of enteric bacteria.