Safety Profile and Enzymatic Specificity of Aspergillus cristatus CCNH008 Characterized by Genomic Analysis

The filamentous fungus Aspergillus cristatus is the principal fermentative microorganism that defines the quality of Fuzhuan brick tea (FBT). However, its specific enzymatic repertoire has not been systematically characterized at the genome level, limiting the broader biotechnological deployment of this fungus. Here we combined whole-genome sequencing, comparative genomic profiling against four well-characterized Aspergillus species (Aspergillus niger, Aspergillus oryzae, Aspergillus nidulans, and Aspergillus fumigatus), CAZyme annotation, and an empirical 19-enzyme activity panel benchmarked against a 50-strain Aspergillus reference set to define the enzymatic specificity of A. cristatus strain CCNH008. The 28.1 Mb hybrid assembly was the most compact genome among the five compared species and encoded the smallest CAZyme repertoire of the compared genomes, with a strongly restrained pectinolytic complement. Enzymatic profiling revealed a distinctive phenotype characterized by moderate cellulolytic capacity, marked polyphenol oxidase and protease activities, and a genotype–phenotype discordance in which pectinase activity ranks among the highest in the 50-strain panel despite a limited predicted pectinolytic gene complement. Comparative genomic profiling positioned CCNH008 between the lignocellulose-degrading specialist A. niger and the starch-adapted food fungus A. oryzae, consistent with adaptation to the unique chemical environment of tea leaves. The safety profile was assessed by in silico PHI/DFVF virulence factor screening and in vitro antifungal susceptibility testing. These findings establish a genomic and enzymatic foundation for the rational exploitation of A. cristatus in tea fermentation and related food biotechnology applications.