Impact of seasonal variability and atmospheric compositions on the bacterial and fungal communities of PM_2.5 in Seoul, Republic of Korea

This study examined particulate matter with a diameter of 2.5 µm or less (PM_2.5) samples to investigate seasonal shifts in bacterial and fungal communities in Seoul, Republic of Korea. To assess these variations and the influence of environmental factors, DNA was extracted from PM_2.5 samples and subjected to sequencing analysis. The results showed distinct seasonal changes in microbial communities. Pseudarthrobacter dominated in winter, Arthrospira in spring, Rhodococcus in summer, and Pelomonas in autumn among the bacterial communities, while Candida in winter, Coprinopsis in spring, and Cutaneotrichosporon in both summer and autumn were prevalent in fungal communities. Bacterial richness peaked in spring, whereas fungal richness was highest in winter. These shifts were driven by environmental factors: air pollutants and chemical compositions had a greater influence in winter and spring, while meteorological conditions, such as temperature and humidity, were dominant in summer and autumn. Functional gene analysis revealed a prevalence of metabolic pathways essential for microbial survival, with fungi showing a higher proportion of saprotrophs, particularly in spring. This comprehensive analysis, considering a wide range of environmental factors including meteorological conditions, air pollutants, and atmospheric organic compounds such as polyaromatic hydrocarbons (PAHs) and dicarboxylic acids (DCAs), provides novel insights into the dynamic relationships between environmental factors and microbial communities in PM_2.5, highlighting the significant role of anthropogenic influences. This research advances our understanding of atmospheric microbial ecosystems and their seasonal dynamics.