Debaryomyces hansenii, a halophile yeast found in shallow sea waters and salty food products grows optimally in 0.

The fermentation and respiration activities of Debaryomyces hansenii were compared with those of Saccharomyces cerevisiae grown to stationary phase with high respiratory activity. It was found that: (a) glucose consumption, fermentation and respiration were lower than for S. cerevisiae; (b) fasting produced a much smaller decrease of respiration; (c) glucose consumed and not transformed to ethanol was higher; (d) in S. cerevisiae, full oxygenation prevented ethanol production but this effect was reversed by CCCP, whereas D. hansenii still showed some ethanol production under aerobiosis, which was moderately increased by CCCP. ATP levels were similar in the two yeasts. Levels of glycolytic intermediaries after glucose addition, and enzyme activities, indicated that the main difference and limiting step to explain the lower fermentation of D. hansenii is phosphofructokinase activity. Respiration and fermentation, which are lower in D. hansenii, compete for the re-oxidation of reduced nicotinamide adenine nucleotides; this competition, in turn, seems to play a role in defining the fermentation rates of the two yeasts. The effect of CCCP on glucose consumption and ethanol production also indicates a role of ADP in both the Pasteur and Crabtree effects in S. cerevisiae but not in D. hansenii. D. hansenii shows an alternative oxidase, which in our experiments did not appear to be coupled to the production of ATP.

Two genes from the halotolerant yeast Debaryomyces hansenii were cloned, DhTRK1 and DhHAK1. These genes encode K + transporters with sequence similarities to the TRK and HAK transporters from Debaryomyces occidentalis and Candida albicans.

A broad range of health benefits have been attributed to resveratrol (RSV) supplementation in mammalian systems, including the increases in longevity. Nonetheless, despite the growing number of studies performed with RSV, the molecular mechanism by which it acts still remains unknown. Recently, it has been proposed that inhibition of the oxidative phosphorylation activity is the principal mechanism of RSV action. This mechanism suggests that RSV might induce mitochondrial dysfunction resulting in oxidative damage to cells with a concomitant decrease of cell viability and cellular life span. To prove this hypothesis, the chronological life span (CLS) of Saccharomyces cerevisiae was studied as it is accepted as an important model of oxidative damage and aging. In addition, oxygen consumption, mitochondrial membrane potential, and hydrogen peroxide (HO) release were measured in order to determine the extent of mitochondrial dysfunction. The results demonstrated that the supplementation of S. cerevisiae cultures with 100 μM RSV decreased CLS in a glucose-dependent manner. At high-level glucose, RSV supplementation increased oxygen consumption during the exponential phase yeast cultures, but inhibited it in chronologically aged yeast cultures. However, at low-level glucose, oxygen consumption was inhibited in yeast cultures in the exponential phase as well as in chronologically aged cultures. Furthermore, RSV supplementation promoted the polarization of the mitochondrial membrane in both cultures. Finally, RSV decreased the release of HO with high-level glucose and increased it at low-level glucose. Altogether, this data supports the hypothesis that RSV supplementation decreases CLS as a result of mitochondrial dysfunction and this phenotype occurs in a glucose-dependent manner.

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