Accumulation of non-superoxide anion reactive oxygen species mediates nitrogen-limited alcoholic fermentation by Saccharomyces cerevisiae.
Throughout alcoholic fermentation, nitrogen depletion is one of the most important environmental stresses that can negatively affect the yeast metabolic activity and ultimately leads to fermentation arrest. Thus, the identification of the underlying effects and biomarkers of nitrogen limitation is valuable for controlling, and therefore optimizing, alcoholic fermentation. In this study, reactive oxygen species (ROS), plasma membrane integrity, and cell cycle were evaluated in a wine strain of Saccharomyces cerevisiae during alcoholic fermentation in nitrogen-limiting medium under anaerobic conditions. The results indicated that nitrogen limitation leads to an increase in ROS and that the superoxide anion is a minor component of the ROS, but there is increased activity of both Sod2p and Cta1p. Associated with these effects was a decrease in plasma membrane integrity and a persistent cell cycle arrest at G(0)/G(1) phases. Moreover, under these conditions it appears that autophagy, evaluated by ATG8 expression, is induced, suggesting that this mechanism is essential for cell survival but does not prevent the cell cycle arrest observed in slow fermentation. Conversely, nitrogen refeeding allowed cells to reenter cell cycle by decreasing ROS generation and autophagy. Altogether, the results provide new insights on the understanding of wine fermentations under nitrogen-limiting conditions and further indicate that ROS accumulation, evaluated by the MitoTracker Red dye CM-H(2)XRos, and plasma membrane integrity could be useful as predictive markers of fermentation problems.
Institute for Biotechnology and Bioengineering, Centre of Genomics and Biotechnology, Universidade de Trás-os-Montes e Alto Douro, Vila Real, Portugal.
Ana
A
Mendes-Ferreira
Belém
B
Sampaio-Marques
Catarina
C
Barbosa
Fernando
F
Rodrigues
Vítor
V
Costa
Arlete
A
Mendes-Faia
Paula
P
Ludovico
Cecília
C
Leão
D000438:Alcohols / Q000378:metabolism*; D001343:Autophagy / Q000187:drug effects; D002453:Cell Cycle / Q000187:drug effects; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D003470:Culture Media / Q000737:chemistry; D005285:Fermentation; D050296:Microbial Viability / Q000187:drug effects; D009584:Nitrogen / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000633:toxicity*; D012441:Saccharomyces cerevisiae / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism* / Q000502:physiology; D013481:Superoxides / Q000032:analysis*
D000438:Alcohols; D003470:Culture Media; D017382:Reactive Oxygen Species; D013481:Superoxides; D009584:Nitrogen