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Increased ethanol accumulation during ethanol fermentation generates stress in yeast cells, which finally reduces the fermentation performance and efficiency. Trehalose, a potential stress protectant, has been reported to regulate the response of yeast to diverse environmental stresses. This study aimed to explore how exogenous trehalose application affects the survival, transcriptome and antioxidant enzymes of Wickerhamomyces anomalus grown under ethanol stress conditions.

Exogenous trehalose was applied to the growth condition of W. anomalus, and optical densitometric method was used to detect contents of intracellular trehalose and MDA and activities of CAT and SOD. The survival was evaluated using spot analysis. Differentially expressed genes (DEGs) were identified through transcriptomics analysis.

The results showed that ethanol stress induced the accumulation of intracellular trehalose, with further exogenous trehalose application improving the survival and alleviating oxidative stress in ethanol-stressed W. anomalus. Transcriptomic results showed that trehalose has pleiotropic regulating effects on ethanol-stressed W. anomalus since most DEGs annotated to energy metabolism, amino acid metabolism, translation, folding, sorting and transport were affected post trehalose addition. Therefore, it is found that trehalose protected W. anomalus against ethanol stress, and these findings provide interesting insights into the mechanistic role of trehalose in improving ethanol stress tolerance of W. anomalus.

(1) Protective effect of exogenous trehalose addition on the survival of ethanol-stressed W. anomalus was proved. (2) Exogenous trehalose addition could partly alleviate oxidative stress induced by ethanol stress and affect transcriptome in W. anomalus.

The purpose of this paper is to identify and analyse the fermentative properties of a strain of indigenous Wickerhamomyces anomalus (W. anomalus) from Rosa roxburghii Tratt (R. roxburghii).

Morphological and molecular methods were used to determine the species of the selected strain W. anomalus C11. The physiological tolerances to glucose, ethanol, citric acid and sulphur dioxide (SO₂) were further assessed by checking the growth of cells, and the oenological performances were proved to measure the related fermentative properties of R. roxburghii wines.

The W. anomalus C11 strain could be grown faster than commercial S. cerevisiae X16 in its logarithmic growth period and had preferable tolerances to glucose, ethanol, citric acid and SO₂. Moreover, this strain of native R. roxburghii yeast W. anomalus C11 produced less sulphuretted hydrogen and had a higher β-glucosidase activity. Furthermore, W. anomalus C11 could reduce the volatile acids, reduce the sourness and enhance volatile aroma richness and complexity of R. roxburghii wines including types of aroma and content thereof. Taken together, the R. roxburghii native yeast W. anomalus C11 may have potential for use in R. roxburghii winemaking.

(1) The fermentative properties of a strain of indigenous W. anomalus (named as C11) from R. roxburghii was evaluated. (2) The strain of W. anomalus C11 had preferable tolerances to glucose, ethanol, citric acid and SO₂. (3) This strain of native R. roxburghii yeast W. anomalus C11 produced less sulphuretted hydrogen and had a higher ß-glucosidase activity. (4) W. anomalus C11 could reduce the volatile acids, reduce the sourness and enhance volatile aroma richness and complexity of R. roxburghii wines including types of aroma and content thereof.