PM2.5 from a broiler breeding production system: The characteristics and microbial community analysis

Characteristics and health impacts of bioaerosols in animal barns: A comprehensive study

Bioaerosols produced during animal production have potential adverse effects on the health of workers and animals. Our objective was to investigate characteristics, antibiotic-resistance genes (ARGs), and health risks of bioaerosols in various animal barns. Poultry and swine barns had high concentrations of airborne bacteria (11156 and 10917 CFU/m3, respectively). Acinetobacter, Clostridium sensu stricto, Corynebacterium, Pseudomonas, Psychrobacter, Streptococcus, and Staphylococcus were dominant pathogenic bacteria in animal barns, with Firmicutes being the most abundant bacterial phylum. Based on linear discriminant analysis effect size (LEfSe), there were more discriminative biomarkers in cattle barns than in poultry or swine barns, although the latter had the highest abundance of bacterial pathogens and high abundances of ARGs (including tetM, tetO, tetQ, tetW sul1, sul2, ermA, ermB) and intI1). Based on network analyses, there were higher co-occurrence patterns between bacteria and ARGs in bioaerosol from swine barns. Furthermore, in these barns, relative abundance of bacteria in bioaerosol samples was greatly affected by environmental factors, mainly temperature, relative humidity, and concentrations of CO2, NH3, and PM2.5. This study provided novel data regarding airborne bio-contaminants in animal enclosures and an impetus to improve management to reduce potential health impacts on humans and animals.

Genomic characterisation of bioaerosols within livestock facilities: A systematic review

Livestock facilities are widely regarded as reservoirs of infectious disease, owing to their abundance in particulate matter (PM) and microbial bioaerosols. Over the past decade, bioaerosol studies have increasingly utilised high throughput sequencing (HTS) to achieve superior throughput, taxonomic resolution, and the detection of unculturable organisms. However, the prevailing focus on amplicon sequencing has limited the identification of viruses and microbial taxa at the species-level. Herein, a literature search was conducted to identify methods capable of overcoming the aforementioned limitations. Screening 1531 international publications resulted in 29 eligible for review. Metagenomics capable of providing rich insights were identified in only three instances. Notably, long-read sequencing was not utilised for metagenomics. This review also identified that sample collection methods lack a uniform approach, highlighted by the differences in sampling equipment, flow rates and durations. Further heterogeneity was introduced by the unique sampling conditions, which makes it challenging to ground new findings within the established literature. For instance, winter was associated with increased microbial abundance and antimicrobial resistance, yet less alpha diversity. Researchers implementing metagenomics into the livestock environment should consider season, the microclimate, and livestock growth stage as influential upon their findings. Considering the increasing accessibility of long-read sequencing, future research should explore its viability within a novel uniform testing protocol for bioaerosol emissions.

Maternal exposure to particulate matter from duck houses restricts fetal growth due to inflammatory damage and oxidative stress

The composition of particulate matter (PM) in poultry farms differs significantly from that of atmospheric PM as there is a higher concentration of microbes on farms. To assess the health effects of PM from poultry farms on pregnant animals, we collected PM from duck houses using a particulate sampler, processed it via centrifugation and vacuum concentration, and subsequently exposed the mice to airborne PM at 0.48 mg/m3 (i.e., low concentration group) and 1.92 mg/m3 (i.e., high concentration group) on the fifth day of pregnancy. After exposure until the twentieth day of pregnancy or spontaneous delivery, mice were euthanized for sampling. The effects of PM from duck houses on the pregnancy toxicity of mice were analyzed using histopathological analysis, enzyme-linked immunosorbent assay, and quantitative real-time polymerase chain reaction (qPCR). The results showed that exposure to PM had adverse effects on pregnant mice that reduced their feed intake in both groups. Microscopic lesions were observed in the lungs and placentas of pregnant mice, and the lesions worsened with increased PM concentrations, as shown by alveolar wall thickening, the infiltration of inflammatory cells in pulmonary interstitium, congestion, edema, and cellular degeneration of placenta. In pregnant mice in the high concentration group, exposure to PM significantly increased the expression of inflammatory cytokines in the lungs and placentas, caused oxidative stress, and decreased estrogen level in the blood. Exposure to PM also resulted in the reduced litter sizes of pregnant mice and shorter body and tail lengths in the fetuses delivered. Beyond that, exposure to PM significantly downregulated the levels of antioxidant factor superoxide dismutase and neurotrophic factor Ngf in the brains of fetuses. Collectively, exposure to a high concentration of PM by inhalation among pregnant mice caused significant pregnancy toxicity that led to abnormal fetal development due to inflammatory damage and oxidative stress. These findings established a foundation for future studies on the underlying mechanisms of pregnancy toxicity induced by exposure to PM.

Variation of PM2.5 and PM10 in emissions and chemical compositions in different seasons from a manure-belt laying hen house

Particulate matter (PM) emissions from animal houses and the corresponding hazard have raised increasing attention during recent years. In this study, a large-scale manure-belt laying hen house located in Beijing, China was selected as the experimental site for the study of the emission rates (ER) and chemical compositions of PM2.5 and PM10 in 3 seasons, namely, summer, autumn, and winter, to investigate their possible influences on ambient air quality and human health. The results showed that the mean ER from the hen house in summer, autumn, and winter were 9.0 ± 1.7, 2.4 ± 0.7, and 1.9 ± 0.7 mg hen-1 d-1 for PM2.5 (P < 0.05), and 30.7 ± 1.1, 12.8 ± 1.5, and 10.9 ± 0.9 mg hen-1 d-1 for PM10 (P < 0.05), respectively. Moreover, large amounts of secondary inorganic aerosols (SIA) were observed inside the house in summer, accounting for 11.4 and 9.6% of indoor PM2.5 and PM10 mass, respectively, compared with the value of <1.4% in autumn and winter. Among the 31 detected elements in indoor PM, arsenic concentration exceeded the threshold set in legislation. Zn had a notably high concentration of 3,403 to 4,432 ng m-3 in indoor PM10, which was 28 to 71 times higher than that in ambient PM10. The findings suggest that the poultry-raising house emit PM2.5 and PM10 containing SIA and toxic heavy-metal elements such as As and Zn to the ambient with much more emissions in summer than in autumn and winter. Considering the increasing development of poultry-raising farming in China, the potential hazard derived from the exhaust of PM2.5 and PM10 should be focused on, especially during summer.

Improving modeling of low-altitude particulate matter emission and dispersion: A cotton gin case study

Monitoring and modeling of airborne particulate matter (PM) from low-altitude sources is becoming an important regulatory target as the adverse health consequences of PM become better understood. However, application of models not specifically designed for simulation of PM from low-altitude emissions may bias predictions. To address this problem, we describe the modification and validation of an air dispersion model for the simulation of low-altitude PM dispersion from a typical cotton ginning facility. We found that the regulatory recommended model (AERMOD) overestimated pollutant concentrations by factors of 64.7, 6.97 and 7.44 on average for PM_2.5, PM₁₀, and TSP, respectively. Pollutant concentrations were negatively correlated with height (p < 0.05), distance from source (p < 0.05) and standard deviation of wind direction (p < 0.001), and positively correlated with average wind speed (p < 0.001). Based on these results, we developed dispersion correction factors for AERMOD and cross-validated the revised model against independent observations, reducing overestimation factors to 3.75, 1.52 and 1.44 for PM_2.5, PM₁₀ and TSP, respectively. Further reductions in model error may be obtained from use of additional observations and refinement of dispersive correction factors. More generally, the correction permits the validated adjustment and application of pre-existing models for risk assessment and development of remediation techniques. The same approach may also be applied to improve simulations of other air pollutants and environmental conditions of concern.

Monodisperse Fluorescent Polystyrene Microspheres for Staphylococcus aureus Aerosol Simulation

Staphylococcus aureus (SA) is one of the most common causes of hospital-acquired infections and foodborne illnesses and is commonly found in nature in air, dust, and water. The spread and transmission of SA aerosols in the air has the potential to cause epidemic transmission among humans and between humans and animals. To effectively provide the timely warning of SA aerosols in the atmosphere, the identification and detection of SA aerosol concentrations are required. Due to their homogeneous physicochemical properties, highly monodisperse submicron polystyrene (PS) microspheres can be used as one of the simulants of SA aerosols. In this study, 800 nm monodisperse fluorescent PS (f-PS) microspheres with fluorescence spectra and particle size distribution similar to those of SA were prepared. The 800 nm monodisperse f-PS microspheres had a fluorescence characteristic peak at 465 nm; in aerosols, 800 nm monodisperse f-PS microspheres with a similar particle size distribution to that of SA were further verified, mainly in the range of 500 nm-1000 nm; finally, it was found that the f-PS microspheres still possessed similar fluorescence characteristics after 180 days. The f-PS microspheres prepared in this study are very close to SA in terms of particle size and fluorescence properties, providing a new idea for aerosol analogs of SA.

Melatonin Ameliorates Apoptosis of A549 Cells Exposed to Chicken House PM2.5: A Novel Insight in Poultry Production

The particulate matter 2.5 (PM_2.5) from the chicken production system can cause lung injury and reduce productivity through prolonged breath as it attaches large amounts of harmful substances and microbes. Melatonin has acted to regulate physiological and metabolic disorders and improve growth performance during poultry production. This research would investigate the apoptosis caused by chicken house PM_2.5 on lung pulmonary epithelial cells and the protective action of melatonin. Here, the basal epithelial cells of human lung adenocarcinoma (A549 cells) were subjected to PM_2.5 from the broiler breeding house to investigate the apoptosis induced by PM_2.5 as well as the alleviation of melatonin. The apoptosis was aggravated by PM_2.5 (12.5 and 25 μg/mL) substantially, and the expression of Bcl-2, Bad, Bax, PERK, and CHOP increased dramatically after PM_2.5 treatment. Additionally, the up-regulation of cleaved caspase-9 and cleaved caspase-3 as well as endoplasmic reticulum stress (ERS)-related proteins, including ATF6 and CHOP, was observed due to PM_2.5 exposure. It is worth noting that melatonin could support A549 cells' survival, in which reduced expression of Bax, Bad, cleaved caspase-3, and cleaved caspase-9 appeared. Concurrently, the level of malondialdehyde (MDA) was down-regulated and enhanced the intracellular content of total superoxide dismutase (T-SOD) and catalase (CAT) after treatment by PM_2.5 together with melatonin. Collectively, our study underlined that melatonin exerted an anti-apoptotic action on A549 cells by strengthening their antioxidant capacity.

Fungal aerosols in rabbit breeding environment: Metagenetic insight into PM2.5 based on third-generation sequencing technology

Fungal aerosols are a vital environmental hazard factor impeding the development of the rabbit breeding industry and threatening public health. This study aimed to determine fungal abundance, diversity, composition, diffusion, and variability in aerosols in rabbit breeding environments. Twenty PM_2.5 filter samples were collected from five sampling sites (i.e. En5, In, Ex5, Ex15, and Ex45) in a modern rabbit farm in Linyi City, China. Fungal component diversity at the species level was analyzed in all samples using third-generation sequencing technology. Results revealed that fungal diversity and community composition in PM_2.5 significantly differed across different sampling sites, and different pollution levels. The highest concentrations of PM_2.5 and fungal aerosols (i.e., 102.5 μg/m³ and 18.8 × 10³ CFU/m³, respectively) were found at Ex5, and these concentrations were found to decrease as the distance from the exit increased. However, no significant correlation was observed between the internal transcribed spacer (ITS) gene abundance and overall PM_2.5 levels, except for Aspergillus ruber and Alternaria eichhorniae. Although most fungi are not pathogenic to humans, zoonotic pathogenic microorganisms that cause pulmonary aspergillosis (e.g., Aspergillus ruber) and invasive fusariosis (e.g., Fusarium pseudensiforme) were observed. The relative abundance of A. ruber was higher at Ex5 than that at In, Ex15, and Ex45 (p < 0.01), and the relative abundance of the fungal species decreased with an increase in distance from the rabbit houses. Moreover, four potential novel strains of Aspergillus ruber were discovered, with 82.9%-90.3% of the nucleotide and amino acid sequences similar to those of reference strains. This study highlights the importance of rabbit environments as a source in shaping fungal aerosol microbial communities. To the best of our knowledge, this is the first study to uncover the initial characteristics of fungal biodiversity and dispersion of PM_2.5 in rabbit breeding environments, contributing to infectious disease control and prevention in rabbits.

The possible role of particulate matter on the respiratory microbiome: evidence from in vivo to clinical studies

Environmental pollution, which contains ambient particulate matter, has been shown to have a significant impact on human health and longevity over the past 30 years. Recent studies clearly showed that exposure to particulate matter directly caused adverse effects on the respiratory system via various mechanisms including the accumulation of free radical peroxidation, the imbalance of intercellular calcium regulation, and inflammation, resulting in respiratory diseases. Recent evidence showed the importance of the role of the respiratory microbiome on lung immunity and lung development. In addition, previous studies have confirmed that several chronic respiratory diseases were associated with an alteration in the respiratory microbiome. However, there is still a lack of knowledge with regard to the changes in the respiratory microbiome with regard to the role of particulate matter exposure in respiratory diseases. Therefore, this review aims to summarize and discuss all the in vivo to clinical evidence which investigated the effect of particulate matter exposure on the respiratory microbiome and respiratory diseases. Any contradictory findings are incorporated and discussed. A summary of all these pieces of evidence may offer an insight into a therapeutic approach for the respiratory diseases related to particulate matter exposure and respiratory microbiome.

Particulate matter in poultry house on poultry respiratory disease: a systematic review

Particulate matter (PM) is one of the essential environmental stressors for the poultry industry in the world. Given its large specific surface area, PM can adsorb and carry a variety of pollutants, including heavy metal ions, ammonia, and persistent organic pollutants such as pathogenic microorganisms. High concentrations of PM induce poultry respiratory inflammation and trigger various diseases. However, the pathogenic mechanism of PM in poultry houses on respiratory diseases has not been clarified due to its complexity and lack of accurate assays. In terms of pathogenesis, there are 3 ways to explain this phenomenon: Inhaled PM irritates the respiratory tract, decreases immune resistance, and causes a respiratory disease; respiratory tract irritation by compounds presents in PM; infections with pathogenic and non-pathogenic microorganisms attached to PM. The latter 2 modes of influence are more harmful. Specifically, PM can induce the respiratory disease through several toxic mechanisms, including ammonia ingestion and bioaccumulation, lung flora dysbiosis, oxidative stress, and metabolic disorders. Therefore, this review summarizes the characteristics of PM in the poultry house and the impact of poultry PM on respiratory disease and proposes potential pathogenic mechanisms.

Intensive poultry farming: A review of the impact on the environment and human health

Poultry farming is one of the most efficient animal husbandry methods and it provides nutritional security to a significant number of the world population. Using modern intensive farming techniques, global production has reached 133.4 mil. t in 2020, with a steady growth each year. Such intensive growth methods however lead to a significant environmental footprint. Waste materials such as poultry litter and manure can pose a serious threat to environmental and human health, and need to be managed properly. Poultry production and waste by-products are linked to NH₃, N₂O and CH₄ emissions, and have an impact on global greenhouse gas emissions, as well as animal and human health. Litter and manure can contain pesticide residues, microorganisms, pathogens, pharmaceuticals (antibiotics), hormones, metals, macronutrients (at improper ratios) and other pollutants which can lead to air, soil and water contamination as well as formation of antimicrobial/multidrug resistant strains of pathogens. Dust emitted from intensive poultry production operations contains feather and skin fragments, faeces, feed particles, microorganisms and other pollutants, which can adversely impact poultry health as well as the health of farm workers and nearby inhabitants. Fastidious odours are another problem that can have an adverse impact on health and quality of life of workers and surrounding population. This study discusses the current knowledge on the impact of intensive poultry farming on environmental and human health, as well as taking a look at solutions for a sustainable future.

Pulmonary microbiota intervention alleviates fine particulate matter-induced lung inflammation in broilers

Fine particulate matter (PM2.5) released during the livestock industry endangers the respiratory health of animals. Our previous findings suggested that broilers exposed to PM2.5 exhibited lung inflammation and changes in the pulmonary microbiome. Therefore, this study was to investigate whether the pulmonary microbiota plays a causal role in the pathogenesis of PM2.5-induced lung inflammation. We first used antibiotics to establish a pulmonary microbiota intervention broiler model, which showed a significantly reduced total bacterial load in the lungs without affecting the microbiota composition or structure. Based on it, 45 AA broilers of similar body weight were randomly assigned to three groups: control (CON), PM2.5 (PM), and pulmonary microbiota intervention (ABX-PM). From 21 d of age, broilers in the ABX-PM group were intratracheally instilled with antibiotics once a day for 3 d. Meanwhile, broilers in the other two groups were simultaneously instilled with sterile saline. On 24 and 26 d of age, broilers in the PM and ABX-PM groups were intratracheally instilled with PM2.5 suspension to induce lung inflammation, and broilers in the CON group were simultaneously instilled with sterile saline. The lung histomorphology, inflammatory cytokines' expression levels, lung microbiome, and microbial growth conditions were analyzed to determine the effect of the pulmonary microbiota on PM2.5-induced lung inflammation. Broilers in the PM group showed lung histological injury, while broilers in the ABX-PM group had normal lung histomorphology. Furthermore, microbiota intervention significantly reduced mRNA expression levels of interleukin-1β, tumor necrosis factor-α, interleukin-6, interleukin-8, toll-like receptor 4 and nuclear factor kappa-B. PM2.5 induced significant changes in the β diversity and structure of the pulmonary microbiota in the PM group. However, no significant changes in microbiota structure were observed in the ABX-PM group. Moreover, the relative abundance of Enterococcus cecorum in the PM group was significantly higher than that in the CON and ABX-PM groups. And sterile bronchoalveolar lavage fluid from the PM group significantly promoted the growth of E. cecorum, indicating that PM2.5 altered the microbiota's growth condition. In conclusion, pulmonary microbiota can affect PM2.5-induced lung inflammation in broilers. PM2.5 can alter the bacterial growth environment and promote dysbiosis, potentially exacerbating inflammation.

Bacterial Community Characteristics Shaped by Artificial Environmental PM2.5 Control in Intensive Broiler Houses

Multilayer cage-houses for broiler rearing have been widely used in intensive Chinese farming in the last decade. This study investigated the characteristics and influencing factors of bacterial communities in the PM2.5 of broiler cage-houses. The PM2.5 samples and environmental variables were collected inside and outside of three parallel broiler houses at the early, middle, and late rearing stages; broiler manure was also gathered simultaneously. The bacterial 16S rRNA sequencing results indicated that indoor bacterial communities were different from the outdoor atmosphere and manure. Furthermore, the variations in airborne bacterial composition and structure were highly influenced by the environmental control variables at different growth stages. The db-RDA results showed that temperature and wind speed, which were artificially modified according to managing the needs for broiler growth, were the main factors affecting the diversity of dominant taxa. Indoor airborne and manurial samples shared numerous common genera, which contained high abundances of manure-origin bacteria. Additionally, the airborne bacterial community tended to stabilize in the middle and late stages, but the population of potentially pathogenic bacteria grew gradually. Overall, this study enhances the understanding of airborne bacteria variations and highlighted the potential role of environmental control measures in intensive farming.

Poultry exposure and environmental protection against asthma in rural children

BACKGROUND

Asthma is one of the most common chronic diseases in childhood, and the prevalence has been increasing over the past few decades. One of the most consistent epidemiological findings is that children living in a farming or rural environment are protected from development of asthma and allergies, but the protective factors in rural China are not clear.

METHODS

A community-based, cross-sectional epidemiological study was performed in a total of 17,587 children aged 5-8 years, 3435 from Hong Kong (urban) and 14,152 from Conghua (rural county in southern China). Asthma and allergic symptoms as well as environmental exposures were ascertained by using a standardized and validated questionnaire.

RESULTS

The prevalence of current wheeze was significantly lower in rural Conghua than that of urban Hong Kong (1.7% vs. 7.7%, p < 0.001). A lower rate of asthma ever was also reported in rural children compared with their urban counterparts (2.5% vs. 5.3%, p < 0.001). After adjusting for confounding factors, exposure to agricultural farming (adjusted odds ratio 0.74, 95% confidence interval: 0.56-0.97) and poultry (0.75, 0.59-0.96) were the most important factors associated with the asthma-protective effect in the rural area. Further propensity score-adjusted analysis indicated that such protection conferred by living in the rural environment was mainly attributable to poultry exposure.

CONCLUSIONS

We confirmed that the prevalence of asthma and atopic disorders was significantly lower in rural children when compared with their urban peers. Exposure to poultry and agricultural farming are the most important factors associated with asthma protection in the rural area.

Size-segregated physicochemical properties of inhalable particulate matter in a tunnel-ventilated layer house in China

This study investigated the physicochemical properties of the particles in a typical commercial laying hen barn in Southeast China. Mass concentrations and size distributions of the particulate matter (PM) and the key components (incl. organic carbon (OC), element carbon (EC), and the water-soluble inorganic ions (WSIIs)) were analyzed. The result shows that the mass concentrations of PM accumulated along with the airflow inside the house, with the total mass of the sampling particles increasing from 843.66 ± 160.74 μg/m³ at the center of the house to 1264.93 ± 285.70 μg/m³ at the place close to exhaust fans. The particles with the aerodynamic equivalent diameter, Dp > 9 μm, coarse particles (2.1 μm < Dp ≤ 9 μm), fine particles (Dp ≤ 2.1 μm) accounted for around 50%, 40%, and 10% of the total mass of the sampling particles, respectively. Mass closure analysis shows secondary inorganic ions (NH₄⁺, SO₄^2- and NO₃^-) were abundant in the fine-mode fraction and OC accounted for more than 40% of the coarse particles. Size distribution analysis shows that the three secondary inorganic ions were bimodally distributed, and the rest tested components were unimodally distributed. The ratios of OC/EC in fine particles were smaller than those in the coarse particles. The equivalent concentration of WSIIs indicated that fine particles were slightly acidic, and the large size particles were slightly alkaline. Knowledge gained from this study will lead to a better understanding of physicochemical properties, sources, and formation of PM.

TBHQ alleviates pyroptosis and necroptosis in chicken alveolar epithelial cells induced by fine particulate matter from broiler houses

Fine particulate matter (PM2.5) from poultry houses has adverse effects on the health of animals and workers. Tert-butylhydroquinone (TBHQ), an antioxidant, is widely used in feed additives. The present study investigated the effects of TBHQ on broiler house PM2.5-induced damage in chicken primary alveolar epithelial cells (AECII) extracted from 16-day-old chicken embryos using the method of differential adhesion. AECII were exposed to PM2.5 and TBHQ alone or in combination, and then, cell membrane integrity, pyroptosis, and necroptosis were detected. Our results showed that PM2.5 from broiler houses caused cell rupture and loss of cell membrane integrity. This result was confirmed by the obvious increases in lactate dehydrogenase (LDH) release and propidium iodide (PI)-positive cells compared to the control group. In addition, the intracellular reactive oxygen species (ROS) levels and the expression levels of pyroptosis-related genes (NLRP3, IL-18, IL-1β) and necroptosis-related genes (RIPK3) were also significantly enhanced. However, TBHQ significantly inhibited intracellular ROS, improved cell viability, and reduced the release of LDH and the number of PI-positive cells compared to those in the PM2.5 group. The expression levels of pyroptosis-related genes (Caspase-1, NLRP3, IL-18, IL-1β) and necroptosis-related genes (RIPK3) were also significantly decreased in the co-treatment group. In summary, these results indicated that TBHQ can alleviate PM2.5-mediated cell pyroptosis and necroptosis in chicken AECII and provide a basis for overcoming the danger that air pollutants from broiler houses pose to the health of chickens.

Comparison of Bacterial Community Structure in PM2.5 within Broiler Houses under Different Rearing Systems in China

Background: In intensive poultry farming, high concentrations of indoor particulate matter (PM) impact production performance and welfare. In this study, PM2.5 level and bacterial community diversity were investigated in a multilayer cage house rearing system (CH) and a net flooring house rearing system (FH) during different growth stages to clarify the effects of the rearing systems on the diversity of airborne bacteria and help improve health management. Methods: The IC and high-throughput sequencing were used for ion composition and bacterial diversity analysis of PM2.5 collected from CH and FH. Results: The concentrations of NH3, CO2 and PM2.5 in CH were significantly lower than FH (p < 0.001) in both middle and late rearing stages. PM concentrations gradually increased with broiler growth only in FH. The water-soluble ions of PM2.5 samples had no significant difference between the two systems (p > 0.05). Firmicutes, Actinobacteria and Proteobacteria were the most abundant phyla in both the atmosphere and the broiler houses, but the composition was significantly different. The bacterial community in the broiler houses had strong correlations with temperature, humidity and PM of extremely high concentrations. Ions had stronger correlations with microbial community structure. Conclusions: The superiority of CH in environmental control over FH indicates that improved techniques in environmental control and breeding management can greatly reduce farming air pollution and improve the health management of broiler houses.

Inflammation-associated pulmonary microbiome and metabolome changes in broilers exposed to particulate matter in broiler houses

The particulate matter (PM) in livestock houses, one of the primary sources of atmospheric PM, is not only detrimental to the respiratory health of animals and farmworkers but also poses a threat to the public environment and public health and warrants increased attention. In this study, we investigated the variation in the pulmonary microbiome and metabolome in broiler chickens exposed to PM collected from a broiler house. We examined the pulmonary microbiome and metabolome in broilers, observing that PM induced a visible change in α and β diversity. A total of 66 differential genera, including unclassified_f_Ruminococcaceae and Campylobacter, were associated with pulmonary inflammation. Untargeted metabolomics was utilised to identify 63 differential metabolites induced by PM and correlated with differential bacteria. We observed that PM resulted in injury of the broiler lung and disruption of the microbial community, as well as causing changes in the observed metabolites. These results imply that perturbations to the microbiome and metabolome may play pivotal roles in the mechanism underlying PM-induced broiler lung damage.

A review of the emergence of antibiotic resistance in bioaerosols and its monitoring methods

Despite significant public health concerns regarding infectious diseases in air environments, potentially harmful microbiological indicators, such as antibiotic resistance genes (ARGs) in bioaerosols, have not received significant attention. Traditionally, bioaerosol studies have focused on the characterization of microbial communities; however, a more serious problem has recently arisen due to the presence of ARGs in bioaerosols, leading to an increased prevalence of horizontal gene transfer (HGT). This constitutes a process by which bacteria transfer genes to other environmental media and consequently cause infectious disease. Antibiotic resistance in water and soil environments has been extensively investigated in the past few years by applying advanced molecular and biotechnological methods. However, ARGs in bioaerosols have not received much attention. In addition, ARG and HGT profiling in air environments is greatly limited in field studies due to the absence of suitable methodological approaches. Therefore, this study comprehensively describes recent findings from published studies and some of the appropriate molecular and biotechnological methods for monitoring antibiotic resistance in bioaerosols. In addition, this review discusses the main knowledge gaps regarding current methodological issues and future research directions.

Distribution characteristics of bioaerosols inside pig houses and the respiratory tract of pigs

Particulate matter (PM) is a carrier of many substances. Microorganisms are vital constituents contained in PM, and their varieties and concentrations are closely connected to human health and animal production. This study aimed to investigate the distribution characteristics of bioaerosols inside a pig house and in the respiratory tract of pigs. Environmental indices inside a nursery pig house were monitored in winter, including temperature, relative humidity, total suspended particulate (TSP), PM₁₀, PM_2.5, NH₃, CO₂, CO and NO. The concentrations of airborne culturable bacteria, fungi and Escherichia coli were detected. Then, 16S rRNA sequencing technology was applied to identify different-sized bioaerosols and bacteria in the respiratory tract of piglets. The results showed that the concentration of airborne culturable bacteria inside the pig house was significantly higher than that outside, and no significant difference was found among culturable fungi and Escherichia coli. The 16S rRNA results showed that the bacterial aerosols presented high similarity to the bacteria in the respiratory tract of piglets. The airborne bacterial aerosols within the size range of 1.1-3.3 µm showed high similarity to the bacteria in the lower respiratory tract (bronchus and lung) of piglets. In addition, four potential pathogenic bacterial genera (Escherichia-Shigella, Streptococcus, Acinetobacter, Pseudomonas) were identified both in the bacterial aerosols and the respiratory tract of piglets. These results will provide a significant scientific basis for exploring the potential risk of aerosols from animal houses to human and animal health.

The source and transport of bioaerosols in the air: A review

Recent pandemic outbreak of the corona-virus disease 2019 (COVID-19) has raised widespread concerns about the importance of the bioaerosols. They are atmospheric aerosol particles of biological origins, mainly including bacteria, fungi, viruses, pollen, and cell debris. Bioaerosols can exert a substantial impact on ecosystems, climate change, air quality, and public health. Here, we review several relevant topics on bioaerosols, including sampling and detection techniques, characterization, effects on health and air quality, and control methods. However, very few studies have focused on the source apportionment and transport of bioaerosols. The knowledge of the sources and transport pathways of bioaerosols is essential for a comprehensive understanding of the role microorganisms play in the atmosphere and control the spread of epidemic diseases associated with them. Therefore, this review comprehensively summarizes the up to date progress on the source characteristics, source identification, and diffusion and transport process of bioaerosols. We intercompare three types of diffusion and transport models, with a special emphasis on a widely used mathematical model. This review also highlights the main factors affecting the source emission and transport process, such as biogeographic regions, land-use types, and environmental factors. Finally, this review outlines future perspectives on bioaerosols.

Evaluation of young chickens challenged with aerosolized Salmonella Pullorum

Salmonella enterica serovar Pullorum (S. Pullorum) is an important pathogen specific to avian species, which poses a serious threat to the poultry industry. The transmission of S. Pullorum occurs both horizontally and vertically but the airborne transmission of S. Pullorum has been neglected historically. In this study, the effects of aerosolized S. Pullorum on young chickens were investigated. The results showed that the colonization and morbidity induced by bioaerosol infection are dose dependent. The bacteria colonized in chicken lung for more than 14 days following the exposure to ≥ 1.25 × 10⁶ CFU/m³ of aerosolized S. Pullorum. Tachypnoea and depression were present in all the chickens between 5 and 7 days after infection, and some died, following the exposure to ≥1.25 × 10⁸ CFU/m³ of aerosolized S. Pullorum. RT-PCR results showed that significant expressions of inflammatory cytokines, including tumour necrosis factor α, interleukin 1β (IL-1β), IL-6, and IL-8 were noted in the lung and spleen. Histopathological examination showed lung swelling, with obvious lesions, including inflammatory cell infiltration, tissue injury, and acute haemorrhage. These results suggest that uncontrolled and detrimental inflammation is caused by a high dose of aerosolized S. Pullorum. These results further extend our understanding of the pathogenicity of air-transmitted S. Pullorum on chickens. RESEARCH HIGHLIGHTS Aerosolized S. Pullorum caused tachypnoea, depression, and lung swelling in chickens. The colonization and morbidity caused by aerosolized S. Pullorum are dose dependent. Detrimental inflammation is caused by high doses of aerosolized S. Pullorum in lung.

New insights into concentrations, sources and transformations of NH3, NOx, SO2 and PM at a commercial manure-belt layer house

Pollutant gases and particulate matters (PM) from livestock facilities can affect the health of animals and farm workers and lead to great social environmental risks. This paper presents a comprehensive study on the characteristics of ammonia (NH₃), nitrogen oxides (NO_x), sulfur dioxide (SO₂) and PM (including PM_2.5 and PM₁₀) in a 100,000-bird manure-belt layer house in suburb Beijing for three typical seasons of summer, autumn and winter. Indoor air was sampled at an exhaust fan of the mechanically ventilated commercial house. The monitored indoor concentrations of NH₃, NO_x, SO₂, PM_2.5 and PM₁₀ were 3.7-5.0 mg m^-3, 17-58 μg m^-3, 0-11 μg m^-3, 100-149 μg m^-3 and 354-828 μg m^-3, respectively. The indoor NH₃ concentrations were largely influenced by the manure removal frequency. The NO_x and SO₂ were mainly sourced from the ambient air, and the NO_x was also partly sourced from manure decomposition in summer. The indoor PM_2.5 and PM₁₀ were largely sourced from the ambient air and the indoor manure, respectively. The abundant indoor NH₃ caused significantly higher NH₄⁺ concentration in the indoor PM₁₀ (7.98 ± 9.04 μg m^-3) than that in the ambient PM₁₀ (3.48 ± 3.52 μg m^-3). Secondary inorganic ions (SO₄^2-, NO₃^- and NH₄⁺) totally contributed 5.7% and 14.6% to the indoor and ambient PM_2.5, respectively; they contributed 2.8% and 8.9% to the indoor and ambient PM₁₀, respectively. Organic carbon was the main component of the PM and accounted for 26.6% and 41.5% of the indoor PM_2.5 and PM₁₀, respectively. Heavy metal elements (Zn, Cu and Cr) were likely transported from feed to manure and finally accumulated in the PM. Given the high emission potential, the air pollutants from animal production suggested potential risks for human health.