Open AccessIterative selection from a Salmonella typhimurium cosmid library can lead to the isolation of an atypically small plasmid
Author(s) -
Lodge Julia M.,
Robey Marianne,
Stephen John,
Brown Nigel L.
Publication year - 1999
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1999.tb13395.x
Subject(s) - cosmid , plasmid , subculture (biology) , biology , salmonella , isolation (microbiology) , genomic library , virulence , selection (genetic algorithm) , microbiology and biotechnology , genetics , bacteria , dna , gene , base sequence , computer science , artificial intelligence
We have constructed a DNA library from a virulent Salmonella typhimurium strain, in an avirulent strain. The process of selecting the components of interest from the library involved iterative growth in liquid culture. This resulted, after four cycles, in the culture becoming homogeneous for a single plasmid, which was much smaller than the average size for the library. We have identified the larger precursor of this plasmid which has two regions of sufficient homology to allow recombination resulting in the formation of the small plasmid. S. typhimurium carrying the small plasmid have a smaller genetic burden than other members of the library and survive better in spent culture medium, facilitating selection on repeated subculture. Such rapid adventitious selection has important implications for isolation of clones of interest from genomic libraries.