Production and localization of beta-fructosidase in asynchronous and synchronous chemostat cultures of yeasts

Abstract

In synchronized continuous cultures of Saccharomyces cerevisiae CBS 8066, the production of the extracellular invertase (EC 3.2.1.26) showed a cyclic behavior that coincided with the budding cycle. The invertase activity increased during bud development and ceased at bud maturation and cell scission. The cyclic changes in invertase production resulted in cyclic changes in amounts of invertase localized in the cell wall. However, the amount of enzyme invertase present in the culture liquid remained constant throughout the budding cycle. Also, in asynchronous continuous cultures of S. cerevisiae, the production and localization of invertase showed significant fluctuation. The overall invertase production in an asynchronous culture was two to three times higher than in synchronous cultures. This could be due to more-severe invertase-repressive conditions in a synchronous chemostat culture. Both the intracellular glucose-6-phosphate concentration and residual glucose concentration were significantly higher in synchronous chemostat cultures than in asynchronous chemostat cultures. In the asynchronous and synchronous continuous cultures of S. cerevisiae, about 40% of the invertase was released into the culture liquid; it has generally been believed that S. cerevisiae releases only about 5% of its invertase. In contrast to invertase production and localization in the chemostat cultures of S. cerevisiae, no significant changes in inulinase (EC 3.2.1.7) production and localization were observed in chemostat cultures of Kluyveromyces marxianus CBS 6556. In cultures of K. marxianus about 50% of the inulinase was present in the culture liquid.

Chemostat cultivation as a tool for studies on sugar transport in yeasts.

“…In contrast to glucose metabolism, disaccharide metabolism in yeasts is not necessarily initiated by uptake of the sugar molecule. For example, in the yeast K marxianus, sucrose is initially hydrolyzed to glucose and fructose by the extracellular enzyme inulinase (91,92). Subsequently, the component hexoses are transported into the cell (Fig.…”

Gts1p stabilizes oscillations in energy metabolism by activating the transcription of TPS1 encoding trehalose-6-phosphate synthase 1 in the yeast Saccharomyces cerevisiae

“…However, whether Snf1 kinase has a function in the shift between metabolic phases in synchronous cultures has not been studied. In relation to this problem, the enzyme activity of invertase, encoded by SUC2, reportedly fluctuated in synchronous continuous cultures [17]. Among the products of many genes involved in the repression and derepression of SUC2 [18,19], Snf1 kinase has a central role in the derepression mechanism by which the kinase removes the Mig1p repressor from the promoter of SUC2 to the cytoplasm after phosphorylation (for review, see [20]).…”