Fungal community succession in the fermentation of black and oolong teas

The quality of fully fermented (black) and partially fermented (oolong) teas is strongly influenced by fungal communities, yet their successional dynamics remain poorly understood. This study characterized the fungal communities in black and oolong teas processed from a single batch of raw leaves, using a multi-locus (ITS1, ITS2, and the LSU) amplicon sequencing approach. Results revealed a deterministic succession, with the fungal community shifting from a Pleosporales -dominated state on fresh leaves to one dominated by Capnodiales during fermentation. Specifically, a core set of resident foliar endophytes, representing a minority of the initial taxa, accounted for over 90% of the final community abundance, underscoring their central role. While both tea types shared this core successional trajectory, their final community structures diverged. Co-occurrence analysis further revealed that the extended fermentation of black tea resulted in a more consolidated and interconnected fungal community compared to oolong tea. These findings demonstrate that tea fermentation acts as a strong ecological filter on the native leaf mycobiome, where processing duration not only selects for specific taxa but also reshapes community-level interactions. • Ascomycota is the dominant fungal phylum throughout the tea fermentation process. • Foliar endophytes were identified as the source of fungal in tea fermentation. • Black tea exhibited higher fungal community connectivity then oolong tea.