Antifungal susceptibility and genomic profile associated with biosynthetic gene clusters of bovine mastitis-derived Aspergillus fumigatus DAH1043FM

The most frequently isolated fungus from mycotic mastitis in cattle is Aspergillus fumigatus , which can cause infection by germinating on the animal's surface to form hyphae that penetrate epithelial and endothelial barriers and initiate mastitis. In this study, the fungal strain DAH1043FM was isolated from the milk of a cow with mastitis and identified as Aspergillus fumigatus by internal transcribed spacer (ITS) region sequencing. Species identity was further confirmed by whole-genome Average Nucleotide Identity (ANI) analysis. A. fumigatus DAH1043FM showed minimum inhibitory concentration (MIC) values of 0.5 μg/mL for amphotericin B and itraconazole, 0.12 μg/mL for posaconazole and voriconazole, 128 μg/mL for fluconazole, and >8 μg/mL for caspofungin, micafungin, and anidulafungin. Comparative Whole-genome sequencing (WGS) with two reference genomes of A. fumigatus , Af293 and A1163, was used to identify genetic variants, such as single nucleotide polymorphisms (SNPs) and other mutations, in genes associated with antifungal resistance, including those involved in drug efflux, ergosterol biosynthesis, echinocandin target pathways, and other resistance-related processes. Furthermore, genome mining identified biosynthetic gene clusters (BGCs) showing substantial similarity to characterized pathways associated with fumiquinazoline (100%), gliotoxin (84%), fumagillin (80%), and trypacidin (71%). These results demonstrate that strain DAH1043FM carries predicted genetic variants in target pathways while exhibiting wild-type susceptibility to azoles alongside off-scale endpoints for echinocandins. Genome analysis of strain DAH1043FM identified predicted secondary metabolite BGCs, highlighting the value of genome-level surveillance for fungal isolates recovered from bovine milk.