Metabolic Remodeling during Long-Lasting Cultivation of the Endomyces magnusii Yeast on Oxidative and Fermentative Substrates

Abstract

In this study, we evaluated the metabolic profile of the aerobic microorganism of Endomyces magnusii with a complete respiration chain and well-developed mitochondria system during long-lasting cultivation. The yeast was grown in batches using glycerol and glucose as the sole carbon source for a week. The profile included the cellular biological and chemical parameters, which determined the redox status of the yeast cells. We studied the activities of the antioxidant systems (catalases and superoxide dismutases), glutathione system enzymes (glutathione peroxidase and reductase), aconitase, as well as the main enzymes maintaining NADPH levels in the cells (glucose-6-phosphate dehydrogenase and NADP+-isocitrate dehydrogenase) during aging of Endomyces magnusii on two kinds of substrates. We also investigated the dynamics of change in oxidized and reduced glutathione, conjugated dienes, and reactive oxidative species in the cells at different growth stages, including the deep stationary stages. Our results revealed a similar trend in the changes in the activity of all the enzymes tested, which increased 2–4-fold upon aging. The yeast cytosol had a very high reduced glutathione content, 22 times than that of Saccharomyces cerevisiae, and remained unchanged during growth, whereas there was a 7.5-fold increase in the reduced glutathione-to-oxidized glutathione ratio. The much higher level of reactive oxidative species was observed in the cells in the late and deep stationary phases, especially in the cells using glycerol. Cell aging of the culture grown on glycerol, which promotes active oxidative phosphorylation in the mitochondria, facilitated the functioning of powerful antioxidant systems (catalases, superoxide dismutases, and glutathione system enzymes) induced by reactive oxidative species. Moreover, it stimulated NADPH synthesis, regulating the cytosolic reduced glutathione level, which in turn determines the redox potential of the yeast cell during the early aging process.

The Lipid Profile of the Endomyces magnusii Yeast upon the Assimilation of the Substrates of Different Types and upon Calorie Restriction

“…This is the most studied and reproducible nongenetic intervention, which, as it has been confirmed by numerous studies, increases lifespan, and improves the organism health at various levels of organization: from unicellular yeast to primates and humans, indicating the involvement of conservative mechanisms universal for all eukaryotes in this process [20,21]. In our studies, the metabolic profile of E. magnusii was studied upon long-lasting cultivation on glycerol and glucose as sole carbon sources [22]. Our results revealed a high redox potential in the late and deep stationary growth phases in glycerol-utilizing cells.…”

Effect of glucose levels on carbon flow rate, antioxidant status, and enzyme activity of yeast during fermentation

“…ROS content in yeast was controlled under the action of antioxidant enzymes and trehalose, glycerol and NADPH, this might also be responsible for the decline in yeast glycerol and trehalose metabolism at 6% and 15% glucose levels. At the 15 g L −1 glucose level, the ROS content will start to decrease at 24 h, which is related to the higher antioxidant enzyme content at 24 h 54,55 …”

“…NADPH is an important substance in yeast in response to oxidative stress, which acts on glutathione to eliminate intracellular ROS in yeast 71 . NADPH is produced and utilized in the metabolism of pentose phosphate and TCA 55,72 . As shown in Table 12, the content of NADPH can reflect the antioxidant status of yeast and indirectly reflect the stress intensity of yeast under different glucose levels.…”

“…52,53 ROS content in yeast was controlled under the action of antioxidant enzymes and trehalose, glycerol and NADPH, this might also be responsible for the decline in yeast glycerol and trehalose metabolism at 6% and 15% glucose levels. At the 15 g L −1 glucose level, the ROS content will start to decrease at 24 h, which is related to the higher antioxidant enzyme content at 24 h. 54,55 Effects of glucose levels on the activity of HK HK is the first enzyme of yeast glycolysis and the key enzyme of yeast metabolism. 27 It controls the carbon flux of the entire yeast metabolic system.…”

“…71 NADPH is produced and utilized in the metabolism of pentose phosphate and TCA. 55,72 As shown in Table 12, the content of NADPH can reflect the antioxidant status of yeast and indirectly reflect the stress intensity of yeast under different glucose levels. In the control group without a carbon source, the content of NADPH in cells at 36 h was 2.2 times higher than that at 6 h. At 24 and 36 h, the NADPH content in the control group was 2.3 times and 1.8 times higher than that in 3 g L −1 glucose level group, respectively.…”