SO(2) protects the amino nitrogen metabolism of Saccharomyces cerevisiae under thermal stress.
Bottom Line: In this study, the influence of elevated temperatures on nitrogen metabolism of a Saccharomyces cerevisiae strain was studied, as well as the effect of different concentrations of SO(2) on nitrogen metabolism under thermal stress conditions.The results obtained revealed that amino nitrogen consumption was lower in the fermentation sample subjected to thermal stress than in the control, and differences in amino acid consumption preferences were also detected, especially at the beginning of the fermentation.Under thermal stress conditions, among the three doses of SO(2) studied (0, 35, 70 mg l(-1) SO(2) ), the highest dose was observed to favour amino acid utilization during the fermentative process, whereas sugar consumption presented higher rates at medium doses.
Affiliation: Departamento de Química Aplicada, Universidad Pública de Navarra, Campus Arrosadía s/n, 31006 Pamplona, Spain. firstname.lastname@example.orgShow MeSH
Related in: MedlinePlus
Mentions: Sugar consumption (%) of control fermentation is compared with that of thermal stress fermentation (F35) in Fig. 1A; these two fermentations were performed with the same initial level of SO2 (35 mg l−1). In this figure, it is observed that the initial sugar consumption rate was similar in both cases; however, after 4 days, the control sample presented a higher rate than the one subjected to thermal stress. In the control sample, 99% of must sugar was consumed, whereas in the sample subjected to thermal stress yeasts consumed 90% of sugar. In cells subjected to thermal stress the passive proton influx towards the cytoplasm is increased, so the intracellular pH decline and this can be a major factor contributing to the inhibition of fermentation rate (Neves and François, 1992). Besides, at the plasma membrane, the increase of the passive proton influx due to thermal stress will act to dissipate the electrochemical potential gradient maintained across this membrane by the action of plasma membrane H+‐ATPase (Serrano, 1991). The electrochemical potential gradient is essential for vital functions such as the maintenance of potassium balance and the regulation of intracellular pH.
Affiliation: Departamento de Química Aplicada, Universidad Pública de Navarra, Campus Arrosadía s/n, 31006 Pamplona, Spain. email@example.com