Taxonomic re-identification and biotechnological potential of a Brazilian Aspergillus section Flavi collection: exploring kojic acid production

Species of Aspergillus section Flavi are recognized for their ability to produce metabolites, such as mycotoxins and organic acids. Kojic acid has gained widespread recognition in the cosmetics market for its efficacy in lightening skin blemishes. The importance of these species makes their correct identification and preservation essential. This study aimed to re-identify, taxonomically, Aspergillus section Flavi strains stored at the URM culture collection (WDCM 604) in Brazil and to investigate their potential for kojic acid production. Initially, 194 Aspergillus section Flavi strains were reactivated and authenticated based on DNA sequences (CaM and BenA). Furthermore, 99 strains were evaluated on synthetic solid medium to verify their ability to produce kojic acid. A representative strain from each species was selected to evaluate kojic acid production via submerged fermentation, using sugarcane molasses and corn steep liquor as carbon and nitrogen sources, respectively. Quantitative analysis of kojic acid was performed by high-performance liquid chromatography. In submerged fermentation, Aspergillus caelatus URM 4242 showed the highest production (10.65 ± 0.4 g/L with a yield of 0.54 g/g). Our results highlight the importance of culture collections, taxonomic re-identification, and assessment of the biotechnological potential of strains deposited in these biobanks.