Cloning in Escherichia coli and molecular analysis of the sucrose system of the Salmonella plasmid SCR-53.

The sucrose utilization system of the conjugative plasmid scr-53 originating from a sucrose-fermenting Salmonella strain has been cloned in Escherichia coli K12 using pBR325 as a vector. Bacteria harboring a recombinant plasmid with a 4.9 kilobase PstI-insert were able to grow in media containing sucrose as the sole carbon source. A gene that directs the synthesis of a beta-D-fructofuranosyl-fructohydrolase enzyme was located on a 2.6 kilobase SalI-EcoRI DNA fragment. Three polypeptides of 60,000, 39,000 and 25,000 daltons were detected by a maxicell system. The advantage of using the resulting plasmids for industrial applications is discussed.