Dynamic changes of fungal community structure of yak Qula during storage

Abstract

Yak Qula is a traditional fermented dairy product from the Tibetan Plateau, but the dynamic changes of its fungal community during storage remain poorly understood. This study employed Illumina MiSeq high-throughput sequencing to investigate the fungal community structure of yak Qula stored for 0 (fresh), 3, and 6 months. Results showed significant succession: at the phylum level, Ascomycota dominance (97.0%–98.2%) was temporarily replaced by increased Basidiomycota (16.2%–28.9%) at 3 months before recovering; at the genus level, fresh Qula dominated by unclassified Dipodascaceae and Galactomyces shifted to Trichosporon and Yarrowia at 3 months, and finally to absolute dominance of Pichia (61.8%–86.2%) at 6 months, with the Shannon index decreasing significantly (P = 0.026). LEfSe analysis identified potential safety concerns including the mycotoxin-producing Aspergillus versicolor (3 months) and the opportunistic pathogen Trichosporon inkin (6 months). SparCC network analysis revealed a dynamic succession of interaction patterns from "tight co-occurrence" to "bimodal mutual exclusion" to "polycentric loose" networks. These findings provide a scientific basis for quality evaluation, safety assessment, and storage optimization of Qula.