Abstract: In this study, a thermophilic fungal strain (HBHF5) producing tannase was identified. Also, the enzymatic properties of tannase from strain HBHF5 were evaluated and transcriptomic analysis of its carbohydrate?active?enzymes (CAZymes) was carried out. We aimed to explore the potential of strain HBHF5 for use in the development of food enzyme preparations. Based on its morphology and ITS sequence alignment analysis, strain HBHF5 was identified as Aspergillus fumigatus. A. fumigatus HBHF5 did not produce tannase under solid-state fermentation (SSF), but it produced both?extracellular and intracellular tannase when cultured under submerged fermentation conditions. The extracellular enzyme was found to be dominant (94%) and its activity was as high as 136 U/mL. Tannase activity was optimal at pH 6.0 and 60 ℃. After treatment at 60 ℃ for 30 min, more than 90% of the initial activity was retained, and the residual activity was over 60% in the pH range of 5.0 to 9.0. The tannase activity was inhibited by some metal ions, such as Cu2+, Fe3+, Mn2+ and Zn2+. Transcriptomic analysis showed?that 239 CAZymes?genes including those encoding amylase, cellulase and pectinase were?expressed when wheat bran was used as the sole carbon source. Among these the most abundant was glycoside hydrolase, accounting for about 70% of the total CAZymes. It has been demonstrated that A. fumigatus HBHF5 is a good producer of tannase and has the potential to be used to develop food enzyme preparations.

Key words: tannase, thermophilic enzyme, astringency removal, transcriptomics, carbohydrate?active?enzymes