Influences of environmental factors on the microbial community characteristics of bioaerosols in a cold region

The frequent occurrence of respiratory diseases in winter populations underscores the need to understand environmental drivers of bioaerosols in cold regions for infection control. Our study revealed impacts of environmental factors on airborne microbial communities in a typical Northeast China megacity (-25 to 0 °C). Bioaerosols originated from anthropogenic activities (coal combustion, agricultural biomass burning), natural sources (soil resuspension), and long-range transport. Some pathogenic genera showed significant negative correlations with particles/T/O₃. RDA and CCA analysis indicated O₃, RH, SO₂ and T dominated bacterial genera structure, and O₃, PM_2.5, and PM_2.5–10 played more significant roles in fungal genera structure. O₃ imposed oxidative damage on most genera. Bacterial abundances responded to RH/SO₂/T due to secondary aerosol formation/coal burning emission source/enzymatic controls, respectively. And fungal significantly positive correlations of Alternaria-PM_2.5 and Mortierella-PM_2.5–10 were attributed to similar sources of fungal genera and pollutants, namely agricultural residue burning, and dust, respectively. PM_2.5, NO₂, and CO were determined as dominant factors for the alpha diversity of bacteria communities. For fungi community, PM_2.5–10 and SO₂ were dominant factors influencing its alpha diversity. Co-occurrence networks indicated intensified bacterial competition and more various bacterial sources with rising PM_2.5, T, NO₂, and CO. And there were competitive fungal interactions with more various fungal sources under elevated pollutants and declining RH. These findings elucidate pollution-bioaerosol linkages in cold urban air, providing a mechanistic basis for controlling microbial community especially pathogens in sub-zero environments amid climate change.