From air to airway: Dynamics and risk of inhalable bacteria in municipal solid waste treatment systems

Municipal solid waste treatment (MSWT) system emits a cocktail of microorganisms that jeopardize environmental and public health. However, the dynamics and risks of airborne microbiota associated with MSWT are poorly understood. Here, we analyzed the bacterial community of inhalable air particulates (PM10, n = 71) and the potentially exposed on-site workers' throat swabs (n = 30) along with waste treatment chain in Shanghai, the largest city of China. Overall, the airborne bacteria varied largely in composition and abundance during the treatment (P < 0.05), especially in winter. Compared to the air conditions, MSWT-sources that contributed to 15 similar to 70% of airborne bacteria more heavily influenced the PM10-laden bacterial communities (PLS-SEM, beta = 0.40, P < 0.05). Moreover, our year-span analysis found PM10 as an important media spreading pathogens (10(4) similar to 10(8) copies/day) into on-site workers. The machine-learning identified Lactobacillus and Streptococcus as pharynx niched featured biomarker in summer and Rhodococcus and Capnocytophaga in winter (RandomForest, ntree = 500, mtry = 10, cross = 10, OOB = 0%), which closely related to their airborne counterparts (Procrustes test, P < 0.05), suggesting that MSWT a dynamic hotspot of airborne bacteria with the pronounced inhalable risks to the neighboring communities.

Automated summary

This study analyzes the bacterial community of air particulates and throat swabs in the waste treatment chain in Shanghai, China. They found that the composition and abundance of airborne bacteria varied greatly during the treatment, especially in winter. The study also identified specific bacteria associated with the inhalable risks to neighboring communities, suggesting a potential spread of pathogens to on-site workers.