Kinetics of growth and glucose transport in glucose‐limited chemostat cultures of Saccharomyces cerevisiae CBS 8066

Abstract

The glucose transport capacity of Saccharomyces cerevisiae CBS 8066 was studied in aerobic glucose-limited chemostat cultures. Two different transport systems were encountered with affinity constants of 1 and 20 mM, respectively. The capacity of these carriers (Vmax) was dependent on the dilution rate and the residual glucose concentration in the culture. From the residual glucose concentration in the fermenter and the kinetic constants of glucose transport, their in situ contribution to glucose consumption was determined. The sum of these calculated in situ transport rates correlated well with the observed rate of glucose consumption of the culture. The growth kinetics of S. cerevisiae CBS 8066 in glucose-limited cultures were rather peculiar. At low dilution rates, at which glucose was completely respired, the glucose concentration in the fermenter was constant at 110 microM, independent of the glucose concentration in the reservoir. At higher dilution rates, characterized by the occurrence of both respiration and alcoholic fermentation, the residual substrate concentration followed Monod kinetics. In this case, however, the overall affinity constant was dependent on the reservoir glucose concentration.

Control of specific growth rate in Saccharomyces cerevisiae

“…for glucose-limited chemostat culture at D50.1 h 21 , an internal glucose concentration of 0.003 mM was calculated, which is close to the 1 mM concentration suggested by Postma et al (1989), (for D50.35 h 21 an internal glucose concentration of 0.025 mM was calculated; see Methods for details).…”

“…Thus for S. cerevisiae it was estimated that the transporter has 78 % of growth control at a clamped glucose concentration of 0.03 mM. The experimental approach we followed is similar to the one of Postma et al (1989) where a K S of 0.11-0.39 mM was determined (although the data could not be described very well by Monod kinetics) with a high-affinity K M of 1 mM. In addition, a residual glucose concentration at D50.1 h 21 of 0.11 mM was measured and an internal glucose concentration of 0.001 mM was calculated (Postma et al, 1989).…”

“…The experimental approach we followed is similar to the one of Postma et al (1989) where a K S of 0.11-0.39 mM was determined (although the data could not be described very well by Monod kinetics) with a high-affinity K M of 1 mM. In addition, a residual glucose concentration at D50.1 h 21 of 0.11 mM was measured and an internal glucose concentration of 0.001 mM was calculated (Postma et al, 1989). Using our theoretical analysis, it can be calculated from these data that the glucose transporter controls m at 55-85 % (dependent on the K S value).…”

Glucose uptake and growth of glucose-limited chemostat cultures of Aspergillus niger and a disruptant lacking MstA, a high-affinity glucose transporter

“…This method was previously used by Postma et al (1989b) to compare in situ glucose uptake of S. cerevisiae chemostat cultures (in situ) with glucose uptake kinetics determined in glucose uptake assays with cells obtained from the chemostat cultures.…”

“…Glucose uptake affected by more than one ratelimiting reaction It is a recurring phenomenon (Diderich et al, 1999;du Preez et al, 2000;Postma et al, 1989b) that specific glucose uptake rates or metabolic quotients for glucose calculated from parameters determined in glucose uptake assays (q up ) Fig. 5.…”