Dust events alter semi-arid urban bioaerosols: Community structure, assembly processes, and functional profiles

Bioaerosols, transported by atmospheric particles, are influenced by dust events, yet their impact on microbial assembly and function remains unclear. This study examined dust-induced shifts in airborne microbial communities in Lanzhou through a multi-omics approach. Bacteria dominated bioaerosols (86.65 % taxonomic groups (TGs)), showing higher richness than fungi, archaea, and viruses. Dust events increased microbial diversity and expanded ecological niches for bacteria, fungi, and archaea, while viral abundance elevated in non-dust periods. Community assembly was primarily stochastic, with dust amplifying stochasticity in bacteria, fungi, and archaea but reducing it in viruses. Functionally, dust enriched functions like hydrocarbon degradation (e.g., xylanolysis, oil bioremediation) and metal cycling (manganese/arsenic transformation), whereas non-dust periods favored photosynthetic and pathogenic metabolism. A divergence in pathogens exists, dust events transport soil-derived pathogens over long distances, while non-dust conditions promote the suspension of viruses and human-related pathogens. Dust-associated microbes in this study originated from northwest deserts (100 % samples), carrying specialized taxa, while non-dust communities derived from mixed sources (north: 66.67 %; northwest: 33.33 %). These findings reveal that dust acts as both a dispersal vector and a functional modulator of microorganisms, with implications for biogeochemical cycling and potential health risk in dust-prone regions.