Abstract
Yeast cells are challenged by various environmental stresses in the process of industrial fermentation. As the currently main organism for bio-ethanol production,
Saccharomyces cerevisiae
suffers from ethanol stress. Some amino acids have been reported to be related to yeast tolerance to stresses. Here the relationship between arginine and yeast response to ethanol stress was investigated. Marked inhibitions of ethanol on cell growth, expression of genes involved in arginine biosynthesis and intracellular accumulation of arginine were observed. Furthermore, extracellular addition of arginine can abate the ethanol damage largely. To further confirm the protective effects of arginine on yeast cells, yeast strains with different levels of arginine content were constructed by overexpression of
ARG4
involved in arginine biosynthesis or
CAR1
encoding arginase. Intracellular arginine was increased by 18.9% or 13.1% respectively by overexpression of
ARG4
or disruption of
CAR1
, which enhanced yeast tolerance to ethanol stress. Moreover, a 41.1% decrease of intracellular arginine was observed in
CAR1
overexpressing strain, which made yeast cells keenly sensitive to ethanol. Further investigations indicated that arginine protected yeast cells from ethanol damage by maintaining the integrity of cell wall and cytoplasma membrane, stabilizing the morphology and function of organellae due to low ROS generation.