Search Results (221)

The study aimed to assess the microbiological quality of the air in three barns that differed in size, housing system, and number of animals in the context of sustainable and safe food production. Air samples were collected four times a year (spring, summer, autumn, and winter) to account for seasonal variations. The abundance of selected microorganisms (mesophilic aerobic bacteria, mold fungi, actinomycetes, Staphylococcus spp. and E. coli) was determined using the impact method and appropriate microbiological media. Simultaneously, the air temperature, relative humidity, and real-time resistive sensor readings for current bioaerosols were measured in the tested rooms. Byre (III) had the lowest mean resistive sensor reading for bioaerosols, while barn (II) had the highest. The mean temperature was lowest in barn (I) and highest in barn (II). The mean relative air humidity was lowest in barn (III) and highest in barn (I). The 60 m² barn had the highest number of microorganisms. Factors conducive to the proliferation of microorganisms in the barn included the use of deep litter, which was removed once a quarter. Additionally, storing manure in close proximity to the barn contributed to an increase in the number of microorganisms in the livestock facility. No excessive air pollution with bacteria or mold fungi was found in any of the studied barns. Overall, the study demonstrates that barn management practices, litter type, microclimatic conditions, and ventilation significantly influence airborne microbial concentrations. These findings provide practical insights for improving environmental hygiene and animal welfare in barns and promoting sustainable development in dairy cattle farming. Full article

Microbiological contamination in public buildings is closely linked to human presence, such as airborne bacteria, fungi, and particulate matter, which strongly influence indoor air quality (IAQ). This study examined the distribution of microorganisms in a museum building in relation to time of day, air-handling unit (AHU) type, and ventilation operating mode. Exhibition rooms without natural light relied entirely on a central heating, ventilation and air conditioning (HVAC) system. Microbiological contamination was assessed using Koch’s passive sedimentation method over a 24 h cycle for two AHUs (I and III) and selected rooms, while CO₂ levels were monitored as indicators of occupancy and ventilation demand in line with EN 16798-1:2019 and ASHRAE 62.1-2022. Although the demand-controlled ventilation system increased the outdoor air fraction from 40% to 70–100% during peak visitor density, localized increases in microbial contamination occurred. AHU I showed higher loads of Staphylococcus sp. and fungi, while AHU III exhibited pronounced fungal peaks influenced by elevated humidity from an open water reservoir. Psychrophilic bacteria reached 140–230 CFU·m⁻³, mesophilic bacteria 230–320 CFU·m⁻³, and fungi up to 740 CFU·m⁻³. Most CFU values remained below commonly referenced upper limits (<1000 CFU·m⁻³), but several peaks exceeded lower recommended thresholds, indicating a need for improvements. Enhanced filtration, humidity control, increased airflow during high occupancy, and reducing moisture sources in AHUs may mitigate microbial growth and improve IAQ in public buildings. Full article

Airborne organic dust has rarely been subject to immunotoxicological analysis. A pilot study was undertaken to link exposure metrics (respirable crystalline silica (RCS), bacteria, fungi, endotoxins (END), peptidoglycans (PGN), (1 → 3)-β-D-glucans (GLU)) with in vitro cytotoxicity and cytokine responses based on analysis of airborne organic dust samples collected during a single work shift at six different facilities. The A549 and BEAS-2B cell lines were used to assess cytotoxicity and proinflammatory cytokine release. The general linear model (GLM) and taxonomic linear ordering were used to identify key determinants and rank facilities by the hazard level they pose. The highest cytotoxicity of organic dust was observed at the sewage treatment plant, while the lowest was at the poultry farm. The most hazardous agents present in organic dust included RCS, aerobic bacteria, fungi, PGN, and GLU. They significantly affected cytokine release, particularly of IL-6 and IL-8. The use of a synthetic measure showed that inhalable organic dust from the composting plant presented the highest potential to induce adverse effects on human health, while the lowest one was characterized by the biomass-fired power plant samples. The open-ended statistical method can significantly increase awareness of occupational hazards and promote more responsible protection for exposed workers. Full article

Air quality management in greenhouses is critical to safeguarding plant health and occupational safety, yet conventional filtration methods often fall short in performance and sustainability. These enclosed environments are prone to the accumulation of bioaerosols, including fungi, bacteria, pollen, and dust particles, which can compromise crop productivity and pose health risks to workers. This review explores recent advancements in air filtration technologies for controlled environments such as greenhouses, where airborne particulate matter, bioaerosols, and volatile organic compounds (VOCs) present ongoing challenges. Special focus is given to the development of filtration media based on electrospun nanofibers, which offer high surface area, tunable porosity, and low airflow resistance. The use of biodegradable polymers in these systems to support environmental sustainability is examined, along with electrospinning techniques that enable precise control over fiber morphology and functionalization. Antimicrobial enhancements are discussed, including inorganic agents such as metal nanoparticles and bio-based options like essential oils. Essential oils, known for their broad-spectrum antimicrobial properties, are assessed for their potential in long-term, controlled-release applications through nanofiber encapsulation. Overall, this paper highlights the potential of integrating sustainable materials, innovative fiber fabrication techniques, and nature-derived antimicrobials to advance air filtration performance while meeting ecological and health-related standards. Full article

This study investigated the bacterial community composition and diversity in air and exercise yard bedding samples from large-scale donkey farms in Liaocheng, China, during summer using 16S rRNA high-throughput sequencing. Air samples were collected from five functional areas of donkey barns, while bedding samples were obtained from eight farms housing Dezhou donkeys. Sequencing analysis revealed 894 operational taxonomic units (OTUs) in air samples and 3127 OTUs in bedding samples. Alpha diversity indices indicated that the mare barn exhibited the highest microbial diversity in air, while the foal barn showed the lowest. Actinobacteriota, Proteobacteria, and Firmicutes were the dominant phyla across different functional areas. Rhodococcus was identified as the predominant airborne genus, representing a potential pneumonia risk in foals. In bedding materials, Firmicutes, Actinobacteriota, and Proteobacteria predominated, with Corynebacterium, Salinicoccus, and Solibacillus as dominant genera. Several potentially pathogenic bacteria were detected, including Rhodococcus, Corynebacterium, Clostridium, Streptococcus, and Escherichia-Shigella. These findings provide critical insights into the microbial ecology of intensive donkey farming environments and offer scientific evidence for developing targeted biosecurity strategies to safeguard animal health and promote sustainable livestock production. Full article

Bioaerosols are a major source of airborne microbial contamination in intensive poultry production systems. Their concentration and community structure can profoundly influence animal health, public health, and the overall safety of the farming environment. However, the dynamic characteristics of bacterial aerosols in enclosed poultry houses during winter remain insufficiently studied. Using Taihang chickens as a model, this study investigated three key production stages—brooding (15 days), growing (60 days), and laying (150 days)—under winter cage-rearing conditions. A six-stage Andersen sampler was employed alongside culture-dependent enumeration and 16S rRNA high-throughput sequencing to analyze variations in bacterial aerosol concentration, particle size distribution, and community succession patterns. The results revealed a significant increase in the concentration of culturable airborne bacteria with bird age, rising from 8.98 × 10³ colony-forming unit (CFU)/m³ to 2.89 × 10⁴ CFU/m³ (p < 0.001). The particle size distribution progressively shifted from larger, settleable particles (≥4.7 μm) toward smaller, respirable particles (<4.7 μm). Microbial sequencing indicated a continuous increase in bacterial alpha diversity across the three stages (Chao1 and Shannon indices, p < 0.05), while beta diversity exhibited stage-specific clustering, reflecting clear differences in community assembly. The composition of dominant bacterial genera transitioned from potentially pathogenic taxa such as Acinetobacter and Corynebacterium during the brooding stage to a greater abundance of beneficial genera, including Bacteroides, Lactobacillus, and Ruminococcus, in later stages. This shift suggests a potential ecological link between aerosolized bacterial communities and host development, possibly related to the aerosolization of gut microbiota. Notably, several zoonotic bacterial species were detected in the poultry house air, indicating potential public health and occupational exposure risks under winter confinement conditions. This study is the first to elucidate the ecological succession patterns of airborne bacterial aerosols in Taihang chicken houses across different growth stages during winter. The findings provide a scientific basis for optimizing winter ventilation strategies, implementing stage-specific environmental controls, and reducing pathogen transmission and occupational hazards. Full article

This research intended to investigate the airborne chemical communication that occurs via volatile substances released by phyllosphere-associated bacteria, and it has been investigated whether it is beneficial to plants. The composition of halotolerant Pseudomonas sp. NEEL19 volatiles and impact on mung bean and fenugreek growth and metabolism were examined through co-culture in PPD. NEEL19 volatile mixtures (NEEL19 V⁺) enhanced the shoot and root length and chlorophyll content of mung bean under different saline conditions on short-term exposure. In particular, total chlorophyll a + b showed percentage increases of 58.15%, 67.00%, and 29.5% at 0, 50, and 100 mM NaCl, respectively. Furthermore, fenugreek seedlings’ biomass, shoot length, and chlorophyll content significantly increased while exposed to NEEL19 V⁺. In order to identify the range of volatile organic compounds (VOCs) that NEEL19 released, SPME-GCMS was utilized. The predominant VOC was dimethyl disulfide, while volatile inorganic compounds (VICs), including CO₂ and NH₃, were examined using the volatile trapping method. Saline stress of 100 mM NaCl influences the quantity and composition of both VOCs and VICs production in NEEL19. The consequences of aqueous NH₄OH (1–5 μL) exposure seed PPD assay disclosed that NH₃ is one of the responsible volatile substances that trigger substantial alterations in shoot length, root length, total chlorophyll, and stomatal structure in mung bean seedlings. Whereas, fenugreek seedlings exhibited a high chlorophyll content overall. This study indicates that the release of volatile mixtures from NEEL19 promotes the growth and development of mung bean and fenugreek seedlings. Full article

Antimicrobial resistance (AMR) in bacteria is a critical global health threat, yet the impact of environmental stressors such as aerosolization on resistance remains unclear. We previously showed that aerosolization can induce antibiotic resistance in Escherichia coli MG1655, a gram-negative pathogen simulant. Here, we investigated Bacillus globigii, a surrogate for the gram-positive pathogen Bacillus anthracis, to assess how aerosolization affects bacterial survival and antibiotic resistance. B. globigii vegetative cells and spores were aerosolized under varying conditions and durations (5, 10, 15, 30, and 45 min) into a sterile, airtight chamber and collected using the wetted wall cyclone (WWC) system. Samples were analyzed via antibiotic susceptibility testing, culture-based assay, and quantitative polymerase chain reaction (qPCR). Vegetative cells exhibited the lowest culturability after 5 and 30 min aerosolization, while spores showed reduced culturability at 15–45 min. Both vegetative cells and spores displayed lowest antibiotic susceptibility profiles after 15 min of aerosolization. Our findings suggest that aerosolization duration and bacterial state (vegetative vs. spores) can influence bacterial survival and development of antibiotic resistance. Understanding these dynamics is essential for designing strategies to mitigate the airborne spread of antibiotic-resistant bacteria. Full article

Rapid detection and identification of airborne bacteria are critical for safeguarding human health, yet current technologies remain inadequate. To address this gap, we developed a multifunctional biochip that synergistically integrated a heptagonal micropillar array with a silver nanostructure–polydopamine–co–chitosan (AgNS@PDA–co–CS) composite gel to achieve highly efficient sampling, capture, enrichment, and in situ SERS detection of airborne bacteria. The integrated micropillar array increased the capture efficiency of S. aureus in aerosols from 11.4% (with a flat chip) to 86.3%, owing to its high specific surface area and its ability to generate chaotic vortices that promote bacterial impaction. Subsequent functionalization with the AgNS@PDA–co–CS gel improved the capture efficiency further to >99.9%, due to the synergistic effect of the gel’s adhesive properties and the abundant capture sites provided by the nanostructure, which collectively ensure robust bacterial retention. The incorporated AgNS also served as SERS-active sites, enabling direct identification of captured S. aureus at concentrations as low as 10⁵ CFU m⁻³ after 20 min of sampling. Furthermore, the platform successfully distinguished among three common bacterial species—S. aureus, E. coli, and Bacillus cereus—based on their SERS spectral profiles combined with principal component analysis (PCA). This work presents a synergistic strategy for simultaneous bacterial sampling, capture, enrichment, and detection, offering a promising platform for rapid airborne pathogen monitoring. Full article

Background: Airborne transmission of bacteria, viruses, and fungal spores poses a major threat in enclosed settings, particularly nursing homes where residents are highly vulnerable. Compressive Heating Air Sterilization Technology (CHAST) applies compressive heating to inactivate microorganisms without reliance on filtration or chemicals. Methods: CHAST efficacy was evaluated in laboratory and deployed for a feasibility and performance validation study of air sterilization in a nursing home environment. Laboratory studies tested prototypes (300–5000 CFM; 220–247 °C) against aerosolized surrogates including Bacillus globigii (Bg), B. stearothermophilus (Bst), B. thuringiensis (Bt), Escherichia coli, and MS2 bacteriophage. Viral inactivation thresholds were further assessed by exposing MS2 to progressively lower treatment temperatures (64.5–143 °C). Feasibility and performance validation evaluation involved continuous operation of two CHAST units in a nursing home, with pre- and post-treatment air samples analyzed for bacterial and fungal burden. Results: Laboratory testing demonstrated consistent microbial inactivation, with most prototypes achieving > 6-log (99.9999%) reductions across bacterial spores, vegetative bacteria, and viruses. A 5000 CFM prototype achieved > 7-log (99.99999%) elimination of B. globigii. MS2 was completely inactivated at 240 °C, with modeling suggesting a threshold for total viral elimination near 170 °C. In the feasibility study, baseline sampling revealed bacterial (35 CFU/m³) and fungal (17 CFU/m³) contamination, dominated by Bacillus, Staphylococcus, Cladosporium, and Penicillium. After 72 h of CHAST operation, discharge air contained no detectable viable organisms, and fungal spore counts showed a 93% reduction relative to baseline return air. Units maintained stable operation (464 °F ± 2 °F; 329–335 CFM) throughout deployment. Conclusion: CHAST reproducibly and scalably inactivated airborne bacteria, viruses, and fungi under laboratory and feasibility field studies, supporting its potential as a chemical-free strategy to improve infection control and indoor air quality in healthcare facilities. Full article

Airborne bacterial aerosols are a significant yet understudied component of intensive poultry farming, particularly in cold climates. This study characterized the concentration, size distribution, and community composition of airborne bacteria in closed-cage broiler houses during winter in Hebei Province, China. Air sampling was conducted at three growth stages (7, 21, and 35 days) and analyzed using culture-based methods and 16S rRNA sequencing. Culturable bacterial concentrations increased significantly with broiler age, from 1.1 × 10³ to 1.6 × 10⁴ CFU/m³. The particle size distribution shifted from a predominance of large particles (≥4.7 µm) at day 7 to a dominance of small, inhalable particles (<4.7 µm) thereafter. Sequencing revealed increasing bacterial richness and diversity with age, alongside significant community structural shifts. Predominant genera included Stenotrophomonas, Lactobacillus, and Ruminococcus. Notably, potential zoonotic pathogens (Shigella and Acinetobacter) were detected in later stages. This study provides critical insights into winter bioaerosol dynamics, highlighting implications for animal welfare, occupational health, and public health. Full article

Environmental problems associated with emergency emissions, indoor air pollution with harmful particles, and the spread of viruses and bacteria make the topic of cleaning indoor air from small particles of pollution relevant. In the event of a dangerous situation associated with the presence of small particles in the air, especially those smaller than 10 μm, methods for quickly cleaning the air from such pollutants are required. One of these new methods is the efficient spraying of fine aerosol using the ultrasound technique. Fine aerosol with a droplet size of about 30–50 μm interacts more effectively with pollutant particles compared to larger aerosols. In this paper, the process of interaction of droplets with a characteristic size of 30–50 μm with airborne pollutant particles sized 0.1–10 μm is theoretically studied. Particular attention is paid to particles sized 0.1–2 μm, which are the most difficult to remove from the air. The work will serve as a theoretical basis for the development of methods for cleaning indoor air of pollutant particles using fine aerosol. Full article

Airborne and surface-residing microorganisms in indoor environments pose potential risks for infectious disease transmission. To address this issue, we developed a composite device combining a generator of vaporized free chlorine components with a fine particle removal filter. Field tests were conducted in occupied university classrooms to evaluate the device’s efficacy in reducing airborne bacterial loads. Airborne bacteria were sampled under three operational conditions [Electrolyzed (+)/Filter (+), Electrolyzed (−)/Filter (+), and Electrolyzed (−)/Filter (−)]. Significant reductions in bacterial counts were observed in the Electrolyzed (+)/Filter (+) condition, with a residual rate of 14.5% after 2.25 h (p = 0.00001). Additionally, surface contact tests demonstrated that vaporized free chlorine components, primarily consisting of hypochlorous acid (HOCl), reduced viable counts of E. coli, P. aeruginosa, and S. aureus by 59.0–99.7% even at a distance of 8.0 m. The concentrations of vaporized free chlorine components during operation remained within safe exposure limits (0–19 ppb), consistent with the effective range reported in prior literature (10–50 ppb). Computational fluid dynamics simulations confirmed the diffusion of vaporized free chlorine components throughout the room, including distant sampling points. These findings suggest the combined use of a vaporized free chlorine generator and a particulate filter effectively reduces microbial contamination in indoor environments, providing a promising approach for infection control in residential and public settings. Full article

This study is the first to investigate the performance of ultraviolet germicidal irradiation (UVGI) in underfloor air distribution (UFAD) systems. A simplified mathematical model is developed to predict airborne pathogen transport and inactivation by upper room UVGI in UFAD spaces. The proposed model is substantiated for the SARS-CoV-2 virus as a simulated pathogen through a comprehensive computational fluid dynamics methodology validated against published experimental data of upper room UVGI and UFAD flows. Simulations show an 11% decrease in viral concentration within the upper irradiated zone when a 15 W louvered germicidal lamp is utilized. Finally, a case study on Mycobacterium tuberculosis (M. tuberculosis) bacteria is carried out using the validated simplified model to optimize the use of return air and UVGI implementation, ensuring acceptable indoor air quality and enhanced energy efficiency. Results reveal that the UFAD-UVGI system may consume up to 13.6% less energy while keeping the occupants at acceptable levels of M. tuberculosis concentration and UV irradiance when operated with 26% return air and a UVGI output of 72 W. Full article

Antimicrobial resistance (AMR) has emerged as a planetary health emergency, driven not only by the clinical misuse of antibiotics but also by diverse environmental dissemination pathways. This review critically examines the role of environmental compartments—water, soil, and air—as dynamic reservoirs and transmission routes for antibiotic-resistant bacteria (ARB) and resistance genes (ARGs). Recent metagenomic, epidemiological, and mechanistic evidence demonstrates that anthropogenic pressures—including pharmaceutical effluents, agricultural runoff, untreated sewage, and airborne emissions—amplify resistance evolution and interspecies gene transfer via horizontal gene transfer mechanisms, biofilms, and mobile genetic elements. Importantly, it is not only highly polluted rivers such as the Ganges that contribute to the spread of AMR; even low concentrations of antibiotics and their metabolites, formed during or after treatment, can significantly promote the selection and dissemination of resistance. Environmental hotspots such as European agricultural soils and airborne particulate zones near wastewater treatment plants further illustrate the complexity and global scope of pollution-driven AMR. The synergistic roles of co-selective agents, including heavy metals, disinfectants, and microplastics, are highlighted for their impact in exacerbating resistance gene propagation across ecological and geographical boundaries. The efficacy and limitations of current mitigation strategies, including advanced wastewater treatments, thermophilic composting, biosensor-based surveillance, and emerging regulatory frameworks, are evaluated. By integrating a One Health perspective, this review underscores the imperative of including environmental considerations in global AMR containment policies and proposes a multidisciplinary roadmap to mitigate resistance spread across interconnected human, animal, and environmental domains. Full article