Spatial Analysis of Airborne Bacterial Concentrations and Microbial Communities in a Large-Scale Commercial Layer Facility

The intensification of poultry production has led to the widespread adoption of highdensity housing and advanced environmental control systems to meet increasing demand. Although these advancements have improved production efficiency, they have also introduced challenges related to environmental hygiene and biosecurity,particularly regarding airborne bacterial contamination.In this study, we conducted a comprehensive spatial analysis of airborne bacterial concentrations in a modern commercial layer facility housing approximately 50,000 laying hens. Air samples were systematically collected at 50 locations within the facility using a six-stage Andersen microbial air sampler to quantify bacterial concentrations. Concurrently, environmental samples, including dust, manure, and intestinal contents, were collected for microbial community characterization using 16S rRNA gene sequencing. The results demonstrated a significant longitudinal gradient in airborne bacterial concentrations, with levels progressively increasing from the air inlet to the outlet and peaking near the exhaust fans. Spatial analysis identified zones with elevated bacterial loads, suggesting areas that could benefit from targeted interventions. Microbial community profiling revealed substantial differences among sample types, with the predominant phyla being Firmicutes, Proteobacteria, Actinobacteria, and Bacteroidetes. Alpha and beta diversity analyses indicated significant variation in microbial diversity and community composition across different environmental niches within the facility. Furthermore, differential abundance analyses identified particular taxa associated with manure exposure and airflow dynamics, emphasizing the role of environmental factors in microbial dispersion.This study provides critical insights into the spatial distribution of airborne bacterial concentrations and the microbial community composition in a large-scale commercial layer facility equipped with advanced environmental control systems. By elucidating the factors influencing microbial dispersion, these findings contribute to the development of evidence-based interventions aimed at improving air quality, enhancing biosecurity, and optimizing poultry health and productivity in intensive production settings.