The Requirement of Oxygen for the Active Transport of Sugars into Yeasts

Abstract

The inducible systems of uptake of P-D-galactopyranosides into Kluyveromyces fragilis, Kluyveromyces marxianus and Debaryumyces polymorphus were studied under aerobic and anaerobic conditions, using both lactose and the non-metabolized analogue, methyl 1 -thio-P-D-galactopyranoside (TMG). A common carrier served both substrates, and aerobic entry was by active transport, involving proton symport. The rate of uptake and the final equilibrium concentration were decreased on adding N,N'-dicyclohexylcarbodiimide, diethylstilbestrol or antimycin A, and active transport was completely abolished by carbonyl cyanide m-chlorophenylhydrazone. Uptake under anaerobic conditions differed markedly from that occurring aerobically : TMG was not concentrated anaerobically, even by strongly fermenting yeasts. Instead, it was transported into the cells by facilitated diffusion, which could sustain a rate of entry of over half the maximum rate observed aerobically. That this difference between aerobic and anaerobic transport into yeasts might apply to glycosides in general, was suggested by the finding that a strain of Saccharomyces cerevisiae also took up maltose by active transport under aerobic conditions, but by facilitated diffusion anaerobically. By contrast, the amino acid, 2-aminoisobutyric acid, was concentrated by Kluyveromyces fragilis, even under anaerobic conditions. The significance of these findings in relation to the Kluyver effect is discussed.

Coordination of sucrose uptake and respiration in the yeast Debaryomyces yamadae

“…This observation is consistent with the prediction made by Sims & Barnett (1978) and Barnett (1981). It implies that, theoretically, the glycolytic flux during growth on sucrose can be controlled at the level of disaccharide uptake, as has been proposed for other yeasts that exhibit a Kluyver effect (Barnett & Sims 1982;Kaliterna e t al., 1995).…”

“…Candida kruisii CBS 6451, Candida naeodendra CBS 6032, Candida peltata CBS 5564, Candida sbehatae CBS 581 3, Debar_yomycesyamadae CBS 7035, Metschnikowia renkaufi CBS 61 1, Hansennla pobmorpba CBS 2575 and Picbia stipitis CBS 5773 were obtained from the Centraalbureau voor Schimmelcultures (Delft, The Netherlands) and maintained on malt agar slants at 4 "C. These strains have all been reported to grow on sucrose aerobically, but not to ferment this disaccharide (Barnett et al, 1990). Screening for the Kluyver effect in shake-flask cultures.…”

“…were reported to be unable to ferment this sugar (Barnett et al, 1990). In many yeasts, including Saccbaromyces cerevisiae, sucrose metabolism is initiated by extracellular hydrolysis, catalysed by invertase, followed by uptake of the monosaccharides.…”

Stimulation of Zero- trans Rates of Lactose and Maltose Uptake into Yeasts by Preincubation with Hexose To Increase the Adenylate Energy Charge

“…Lactose uptake by K. lactis is mediated by a transport system inducible by lactose and galactose (9) and is an active process that permits the intracellular accumulation of lactose against a concentration gradient (6, 9). A lactose/H ϩ symport is believed to be responsible in this and related Kluyveromyces species (4,7,9,44).…”

“…Because lactose uptake by Kluyveromyces yeasts occurs by a proton symport (4,7,9), it depends on the transmembrane proton motive force that is generated by the plasma membrane H ϩ /ATPase. The low ATP levels and adenylate EC expected (3) in yeasts harvested before diauxie and then starved, even briefly, might restrict zero-trans lactose uptake.…”