Analysis of the Morphological Characteristics of PM2.5 and Its Microbiological Composition in a Fattening Pig House

Particulate matter (PM2.5) in pig houses and the microorganisms in PM2.5 restrict the sustainable development of the pig industry and have a negative influence on environmental sustainability. This study aimed to investigate the morphological characteristics and diel microbial composition of PM2.5 in fattening pig sheds and explore how changes in the diel microbial composition of PM2.5 correlate with environmental factors and sources. To this end, environmental data from a fattening pig house were monitored, and PM2.5, feed, and faecal particles were examined using electron microscopy. Additionally, the bacterial and fungal assemblages contained in PM2.5 were analysed using 16S and 18S rRNA gene sequencing, respectively. The results showed that NH3, CO2, temperature, and relative humidity were significantly higher at night than during the day. PM2.5 particles from the fattening pig house exhibited different morphologies such as spherical, flocculent, and chain structures. The microbial diversity and bacterial assemblage showed significant variations, which were related to diel environmental factors in the fattening house. In addition, faeces may be the main source of airborne bacteria and feed may be the main source of airborne fungi in fattening houses. These findings provide a scientific basis for exploring the potential risks of the morphological characteristics of PM2.5 and its microbial composition to human and animal health. Additionally, they contribute to the sustainable development of the pig industry and the protection of the environment.