Effect of oxygen tension on stability and expression of a killer toxin chimeric plasmid in a chemostat culture of Saccharomyces cerevisiae

Summary The effects of oxygen tension and dilution rate on expression and stability of killer toxin chimeric plasmid (pADH-10A) in transformants of wine yeast (Montrachet 522) were investigated using a glucose-limited chemostat culture. Killer toxin activity increased as a function of dilution rate when transformants were grown in N₂ or air, but not in 100% O₂. Killer transformants grown in the presence of N₂ had 2–4 fold and 10–15 fold higher toxin expression than that in the presence of air and 100% O₂, respectively. Plasmid stability increased as a function of dilution rate, regardless of the oxygen tension used. However, transformants grown in air gave the highest plasmid stability.Paper Number 10918 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, NC 27695. The use of trade names in this publication does not imply endorsement by the North Carolina Agricultural Research Service of the products named. nor criticism of similar ones not mentioned.