Abstract: In this study, Zygosaccharomyces rouxii was cultured in hypertonic medium (80% sugar content) and basic medium, respectively. Optical density was monitored by a UV-Vis spectrophotometer for examining the growth of Z. rouxii. The intracellular materials were identified by silylation derivatization-gas chromatography-mass spectrometry (GC-MS). The extracellular substances were identified by head-space solid phase micro-extraction (HS-SPME) coupled to GC-MS. The data were analyzed by principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA). The results showed that the OD value of Z. rouxii increased logarithmically with culture time in high glucose medium. Thirty-six and 47 extracellular substances were identified from Z. rouxii at the logarithmic phase in high glucose medium and basic medium, respectively, and 45 extracellular substances were produced by Saccharomyces cerevisiae at the logarithmic phase in basic medium. Under hyperosmotic conditions, Z. rouxii mainly produced alcohols and esters, but did not produce ketones. The three samples were clearly discriminated by PCA, indicating significant differences among them. Both the R2 and Q2 of the PLS-DA model were close to 1, indicating high reliability. The characteristic substances of Z. rouxii under hypertonic condition including 7-octenoic acid ethyl ester, 3-(methylthio) propyl acetate, 2-tridecanol, pentadecanoic acid 3-methylbutyl ester, 9-decenoate, 3-(methylthio)-1-propanol, 2-decanol were selected based on variable importance in the projection (VIP) value. 83 intracellular components were identified, and 23 of these compounds were detected to present in both cultures. A total of 27 intracellular substances were found to exhibit significant differences between these two cultures, suggesting that Z. rouxii is able to withstand high osmotic pressure by producing some sugars, alcohols, acids and other substances involved in sugar metabolism and energy metabolism. The results of this study can provide a theoretical basis for further insights into the resistance of Z. rouxii to osmotic pressure.

Key words: Zygosaccharomyces rouxii, high sugar osmotic pressure, silylation derivatization, head-space solid phase micro-extraction (HS-SPME), gas chromatography-mass spectrometry (GC-MS)