Abstract: A strain of Thermoascus aurantiacus, designated as DQ-1, was isolated from high-temperature Daqu for Jiang-flavor baijiu. Its growth characteristics and whole genome sequence as well as volatile compounds produced by it in solid-state fermentation (SSF) were analyzed. The results indicated that T. aurantiacus DQ-1 was capable of growth within a temperature range of 40 to 55 ℃. This strain produced pronounced floral and fruity aromas and demonstrated the ability to utilize various carbon and nitrogen sources. Whole genome sequencing showed that the strain had the potential for carbohydrate and amino acid metabolism, contributing to the formation of flavor substances in Daqu. Furthermore, analysis by headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) showed that SSF using strain DQ-1 produced a variety of flavor compounds, among them, alcohols being the major ones. After 8 days of fermentation at 45 ℃, the contents of phenylethanol, benzyl alcohol and pyrazine reached up to 126, 32.44 and 2.49 μg/g, respectively. In addition, temperature had an important effect on the aroma production of the strain. We identified 38 fermentation products that significantly differed between 40 and 45 ℃. Among these, the contents of phenylethanol, benzyl alcohol, benzaldehyde, phenylacetaldehyde, pyrazine and most flavor ester compounds increased significantly with increasing temperature. This study provides a data reference for exploring the application value of T. aurantiacus and also provides genetic data for the production of flavor compounds by T. aurantiacus in high-temperature Daqu for Jiang-flavor baijiu.

Key words: Jiang-flavor baijiu; high-temperature Daqu; Thermoascus aurantiacus; whole genome sequencing; volatile compounds; solid-state fermentation