Biochemistry and Biotechnology
Wiley InterScience Backfile Collection 1832-2000
Process Engineering, Biotechnology, Nutrition Technology
Plasmid loss kinetics for Saccharomyces cerevisiae transformed with the 2-μm DNA-based-plasmid pUCKm8 were measured in nonselective and selective media. The plasmid pUCKm8 gives the organism two new phenotypes: resistance to the wide spectrum antibiotic G418 sulfate, and the ability to produce the enzyme, β-lactamase. Plasmid stability was determined using the production of β-lactamase as a marker. The effect of G418 on the growth rates of all organisms present in the culture and on plasmid stability was also determined. Mathematical models describing plasmid loss kinetics during exponential growth for both nonselective and selective conditions are used to simulate the experimental data. In nonselective medium, over 80% of the cells still exhibited the desired phenotype after 50 doublings. In medium containing G418, improvements in plasmid stability were only marginal due to the appearance of antibiotic-resistant cells.
Type of Medium: