Arginine: A novel compatible solute to protect Candida glabrata against hyperosmotic stress

The present study investigated the effect of intracellular arginine accumulation, either through imported from the extracellular environment or by cellular synthesis, on the growth of the yeast, Candida glabrata under hyperosmotic stress. Compared with medium with no arginine supplementation, in the presence of 0.5 g/L arginine, growth expressed in terms of dry cell weight was found to increase by 173.7% (5.2 g/L) or 121.4% (0.31 g/L) in media with osmolarities of 2603 mOsmol/kg or 3324 mOsmol/kg, respectively. Under hyperosmotic conditions, transcription of genes encoding enzymes for arginine degradation decreased while that of genes encoding enzymes for arginine biosynthesis increased. Overproduction of two key enzymes of arginine synthesis pathway, N-acetyltransferase and N-acetylglutamate kinase, resulted in an increase in cellular arginine content and promoted cell growth under hyperosmotic stress. These results indicated that arginine functions as a compatible solute to improve the osmotic stress resistance of C. glabrata.