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Aspergillus fungi are extensively used in traditional food fermentation, so their functions, mechanisms, and safety risks are worth exploring. In this study, a dominant fungal strain (P1) was isolated from a fermented pu-erh tea and identified as A. luchuensis by phylogenetic analysis of fungal internally-transcribed spacer sequencing, partial β-tubulin and calmodulin genes. A pure-strain fermentation of tea leaves was developed, and tea compounds were analyzed by widely-targeted metabolomics, using high-performance liquid chromatography (HPLC) and liquid chromatography mass spectrometry (LC-MS). The mycotoxins, aflatoxin (B1, B2, M1 and M2), fumonisin B1 and B2, ochratoxin A, citrinin, were not detected in fermented tea leaves using methods in the National Standard of the Peoples' Republic of China. The genome of 36.60 Mb with 11,836 protein-coding genes was sequenced by PacBio sequencing and annotated. Expression of fungal genes during fermentation was analyzed by Illumina HiSeq 2500; genes encoding enzymes including glycoside hydrolases, phenolic acid esterases, laccases, tyrosinases, dehydrogenases, peroxidases, dioxygenases, monooxygenases, decarboxylases and O-methyltransferases were identified. These enzymes catalyze hydrolysis, oxidation, ring cleavage, hydroxylation, decarboxylation and O-methylation of phenolic compounds , significantly (p < 0.05) changing the phenolic compound composition. While, phenolic compounds were degraded through degradation of aromatic compounds pathways and xenobiotics biodegradation and metabolism pathways. These findings advance knowledge of the functions and mechanisms of action of Aspergillus in traditional food fermentation., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022. Published by Elsevier Ltd.)

Aspergillus amstelodami A1 isolated from Pu-erh tea was inoculated in sterilized or unsterilized sun-dried green tea leaves to develop pure culture fermentation and enhanced fermentation (EF) of Pu-erh tea. The results showed that the content of tea polyphenols and five catechins in tea decreased significantly, and the content of thearubigins and theabrownins increased significantly after pure culture fermentation. Compared with natural fermentation, the levels of soluble sugars and theabrownins in EF were significantly higher, whereas the levels of gallic acid, (+)-catechin, (-)-epicatechin, (-)-epigallocatechin and caffeine were significantly lower; the scores of sensory evaluation including appearance, color of infusion, taste, aroma and infused leaves in EF were significantly higher; while the value of a* and b* of EF's tea infusion were higher and the value of L* was lower. A. amstelodami A1 didn't become the dominant fungi in EF, while the microbial communities in EF were different from those in NF. Therefore, the enhanced fermentation by inoculation of A. amstelodami A1 changed the chemical components of tea leaves through the synergistic effect with other microorganisms, therefore improving the sensory quality of Pu-erh tea. [ABSTRACT FROM AUTHOR]