title: Fermentation kinetics of recombinant yeast in batch and fed-batch cultures.
abstract: Fed-batch cultures of recombinant microorganisms have attracted attention as they can separate cell growth stage from cloned-gene expression phase during fermentations. In this work, the effect of different glucose feeding strategies on cell growth and cloned gene expression was studied during aerobic fed-batch fermentations of recombinant yeast, containing the plasmid pRB58. The plasmid contains the yeast SUC2 gene, which codes for the enzyme invertase. Some feeding policies resulted in a constant glucose concentration inside the fermentor, while others deliberately introduced a cyclic variation. The cell mass yield was found to be higher at low glucose concentrations, thus indicating a shift to the more energy-efficient respiratory pathway. The SUC2 gene expression was derepressed at glucose levels below 2 g/L. The response of specific invertase activity to changes in the medium glucose concentration was found to be almost immediate.
authors.affiliation: School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907, USA.
authors.forename: A
authors.initials: A
authors.lastname: Patkar
authors.forename: J H
authors.initials: JH
authors.lastname: Seo