PM_2.5 from a broiler breeding production system: The characteristics and microbial community analysis

Particulate matter (PM) released from the processes of livestock production has a negative impact on the health of animals and workers. Herein, the concentration, major chemical components, morphology and microbiological compositions of particulate matter 2.5 (PM_2.5, particles with aerodynamic diameter less than 2.5 μm) in a broiler breeding house were investigated. The results showed that the PM_2.5 distribution in the chicken house was affected by the illumination, draught fans, chicken frame structure and activity of the chickens in the broiler breeding house. Component analysis showed that organic carbon (OC) accounted for the largest proportion, and followed by element carbon (EC), SO₄^2-, NO₃^-, NH₄⁺, Na⁺, K⁺ and Ca²⁺. Ultrastructural observations revealed that the shape of PM_2.5 had a round, rectangular, chain-like and irregular shape. The concentration of endotoxin was approximately 0.3 EU/m³. Microbiological analysis showed that at the genus level, the pathogenic bacteria included Staphylococcus, Corynebacterium, Enterococcus, Parabacteroides, Escherichia and Megamonas. The abundant harmful fungi were Aspergillus, Scopulariopsis, Wallemia, and Fusarium. Through redundancy analysis (RDA) analysis, we determined that OC, EC, Na⁺, K⁺, and NH₄⁺ had strong correlations with Brachybacterium, Brevibacterium, Corynebacterium, Escherichia, Scopulariopsis and Microascus. SO₄^2- was closely related to Scopulariopsis and Salinicoccus. Salinicoccus was also strongly correlated with NO₃^-. Our results indicated that feed, faeces, and outside soot are contributed to the increase in PM_2.5 concentration in the chicken house, while the sources of the dominant bacterial and fungi might be feed, faeces, suspended outside soil and cereal crops.