Human Contact Frequency as a Dominant Ecological Driver of Fungal Community Assembly and Homogenization in Public...

As modern populations spend the majority of their time indoors, understanding indoor microbial ecology is crucial for public health. While research has addressed abiotic pollutants, the ecological dynamics of surface-associated mycobiomes remain insufficiently understood. This study assessed fungal communities across 25 types of public facilities in South Korea to evaluate the relative influence of environmental parameters and human-driven factors. A total of 327 surface samples from six surface types (handles, tables, chairs, walls, pillars, floors) were analyzed using internal transcribed spacer (ITS) sequencing, yielding 27 million reads and 31,721 amplicon sequence variants (ASVs). Although temperature and humidity significantly correlated with airborne fungal concentration, they exerted minimal influence on community diversity and structure. Instead, the intensity of human contact with indoor surfaces emerged as a primary driver of fungal community composition. We found that the relative abundance of the human-associated genus Malassezia is strongly associated with two distinct ecological states of indoor surface mycobiomes; high-Malassezia samples exhibited significantly distinct communities (ANOSIM R = 0.217, p < 0.001) and dense co-occurrence networks among genera of potential clinical relevance, with strong correlations between Malassezia and both Aspergillus and Cladosporium (|corr| = 0.81). These Malassezia-associated patterns persisting across diverse facilities demonstrate that human-driven microbes are the primary ecological drivers of surface mycobiomes in public spaces, providing foundational evidence for human contact-based microbial assessments in public health monitoring and hygiene-conscious environment design.