Characterization of Biological Aerosols Over Northeast India: A Metagenomic Approach

Northeast India is considered as one of the major biodiversity hotspots in the world but the region is underexplored for their microbial biodiversity. Extensive characterization of biological aerosol (bioaerosol) samples collected from various locations of Northeast India was carried out for all the four seasons in a year. These were characterized in terms of particulate matters (inhalable, thoracic, and alveolic), their constituents (pollens, fungal spores, animal debris, and non-biological components), and finally the bacterial diversity was determined by DNA based metagenomic approach. The non-biological (non-viable) component of aerosols is found to vary from 30- 89% in pre-monsoon season which coexists with pollens (4-20%), animal debris (1-24%) and fungal spores (1-17%). The highest number of culturable microbial population in terms of CFU count was observed in the samples collected in pre-monsoon season (i.e., 125.24-632.45 CFU/m3) and the lowest CFU was observed in monsoon season (i.e., 20.83- 319.0 CFU/m3). The metagenomic approach with the samples collected during pre-monsoon season showed a total of bacterial 184 OTUs (operational taxonomic units) with 28,028 abundance count comprising with 7 major phylum, 6 classes, 10 orders, 15 families, 13 genus, and 8 species of bacteria. The species level distribution clearly shows the presence of Gammaproteobacteria (52%) most abundantly followed by Bacilli (21%), Alphaproteobacteria (14%), Betaproteobacteria (5%, Flavobacteria (5%), and Sphingobacteria (3%). It is the first report from entire Northeast India to uncover bacterial diversity in aerosol samples through DNA based metagenomic approach.

Aerosol tracer testing in Boeing 767 and 777 aircraft to simulate exposure potential of infectious aerosol such as SARS-CoV-2

The COVID-19 pandemic has reintroduced questions regarding the potential risk of SARS-CoV-2 exposure amongst passengers on an aircraft. Quantifying risk with computational fluid dynamics models or contact tracing methods alone is challenging, as experimental results for inflight biological aerosols is lacking. Using fluorescent aerosol tracers and real time optical sensors, coupled with DNA-tagged tracers for aerosol deposition, we executed ground and inflight testing on Boeing 767 and 777 airframes. Analysis here represents tracer particles released from a simulated infected passenger, in multiple rows and seats, to determine the exposure risk via penetration into breathing zones in that row and numerous rows ahead and behind the index case. We present here conclusions from 118 releases of fluorescent tracer particles, with 40+ Instantaneous Biological Analyzer and Collector sensors placed in passenger breathing zones for real-time measurement of simulated virus particle penetration. Results from both airframes showed a minimum reduction of 99.54% of 1 μm aerosols from the index source to the breathing zone of a typical passenger seated directly next to the source. An average 99.97 to 99.98% reduction was measured for the breathing zones tested in the 767 and 777, respectively. Contamination of surfaces from aerosol sources was minimal, and DNA-tagged 3 μm tracer aerosol collection techniques agreed with fluorescent methodologies.

Air ozonization for prevention of bacterial and viral infections

Objective. To assess the effectiveness of the low-dose air ozonation for disinfection of the air in the working room. Materials and methods. We investigated 90 air samples (3 samples were taken weekly before and after the production meeting using the automatic sampling device of biological aerosols of air PU-1B). The total bacterial contamination, the content of staphylococci and mold spores were determined. Ozonation of the room (83.3 m3) was carried out for 20 minutes by means of domestic ozonator. The accumulated dose of ozone was 133.3 mg (1.6 mg/m3). Statistical data processing was carried out using the MedStat licensed program. The median, median error (Me me), left and right 95 % confidence intervals (95 % CI) were calculated. Paired comparisons were made using Wilcoxon's T-test. Results. After the meeting, the total bacterial contamination of the air was 56.0 9.3 (47.078.0) CFU. The content of staphylococci and mold spores in the air was 85.5 12.5 (76.0100.0) and 44.5 6.5 (32.054.0) CFU, respectively. After ozonation, the total bacterial contamination of the air was 14.5 3.6 (10.021.0) CFU. The content of staphylococci and mold spores in the air after ozonation was 35.5 6.7 (25.052.0) and 26.0 5.0 (18.032.0) CFU, respectively. Ozonation of the room provided a significant decrease (p 0.001) in all three of the above indicators. The room ozonation carried out promoted a reliable decrease (p 0.001) in all the above mentioned parameters. Conclusions. The above data and analysis of the literature show the possibility of using low doses of ozone for the prevention of bacterial, fungal and viral infections including SARS-CoV-2. Further study and development of reasonable modes of ozone disinfection, including low doses of ozone, is needed, as well as determination of the efficiency degree of air disinfection with non-toxic gas concentrations.

Aerosol tracer testing in Boeing 767 and 777 aircraft to simulate exposure potential of infectious aerosol such as SARS-CoV-2

The COVID-19 pandemic has reintroduced questions regarding the potential risk of SARS-CoV-2 exposure amongst passengers on an aircraft. Quantifying risk with computational fluid dynamics models or contact tracing methods alone is challenging, as experimental results for inflight biological aerosols is lacking. Using fluorescent aerosol tracers and real time optical sensors, coupled with DNA-tagged tracers for aerosol deposition, we executed ground and inflight testing on Boeing 767 and 777 airframes.Analysis here represents tracer particles released from a simulated infected passenger, in multiple rows and seats, to determine the exposure risk via penetration into breathing zones in that row and numerous rows ahead and behind the index case. We completed over 65 releases of 180,000,000 fluorescent particles from the source, with 40+ Instantaneous Biological Analyzer and Collector sensors placed in passenger breathing zones for real-time measurement of simulated virus particle penetration.Results from both airframes showed a minimum reduction of 99.54% of 1 µm aerosols from the index source to the breathing zone of a typical passenger seated directly next to the source. An average 99.97 to 99.98% reduction was measured for the breathing zones tested in the 767 and 777, respectively. Contamination of surfaces from aerosol sources was minimal, and DNA-tagged 3 µm tracer aerosol collection techniques agreed with fluorescent methodologies.

Airborne transmission of hospital pathogens

For decades, there have been a number of controversial issues regarding the airborne transmission of hospital pathogens. Here we decided to perform a critical review on this topic in light of the current COVID-19 pandemic. We summarise the existing knowledge on biological aerosols including techniques of their generation, propagation of bioaerosol particles in a hospital environment, particle size-, shape- and composition-dependent airborne transmission, and microorganisms inhabitating such particles. It is still unclear which of the particles transfer the pathogens, which of the pathogens are capable of adhering to the particulate matter, and whether such adhesion affects pathogen virulence. Intriguingly, viruses, bacteria and fungi seemingly have distinct patterns of interactions with the bioaerosols. Moreover, particle formation and their colonization may be separated in time, further complicating the puzzle. Apparently, pathogen interactions with the particulate matter are of paramount importance to better understand the role of bioaerosol particles as a potential pathogen reservoir in the hospital environment and to properly assess the influence of environmental pollutants, novel biomedical materials and treatment technologies on airborne transmission of hospital pathogens.

Airborne Bacterial and Eukaryotic Community Structure across the United Kingdom Revealed by High-Throughput Sequencing

Primary biological aerosols often include allergenic and pathogenic microorganisms posing potential risks to human health. Moreover, there are airborne plant and animal pathogens that may have ecological and economic impact. In this study, we used high-throughput sequencing techniques (Illumina, MiSeq) targeting the 16S rRNA genes of bacteria and the 18S rRNA genes of eukaryotes, to characterize airborne primary biological aerosols. We used a filtration system on the UK Facility for Airborne Atmospheric Measurements (FAAM) research aircraft to sample a range of primary biological aerosols across southern England overflying surface measurement sites from Chilbolton to Weybourne. We identified 30 to 60 bacterial operational taxonomic units (OTUs) and 108 to 224 eukaryotic OTUs per sample. Moreover, 16S rRNA gene sequencing identified significant numbers of genera that have not been found in atmospheric samples previously or only been described in limited number of atmospheric field studies, which are rather old or published in local journals. This includes the genera Gordonia, Lautropia, and Psychroglaciecola. Some of the bacterial genera found in this study include potential human pathogens, for example, Gordonia, Sphingomonas, Chryseobacterium, Morganella, Fusobacterium, and Streptococcus. 18S rRNA gene sequencing showed Cladosporium to be the major genus in all of the samples, which is a well-known allergen and often found in the atmosphere. There were also genetic signatures of potentially allergenic taxa; for example, Pleosporales, Phoma, and Brassicales. Although there was no significant clustering of bacterial and eukaryotic communities depending on the sampling location, we found meteorological factors explaining significant variations in the community composition. The findings in this study support the application of DNA-based sequencing technologies for atmospheric science studies in combination with complementary spectroscopic and microscopic techniques for improved identification of primary biological aerosols.

Molecular markers of biomass burning and primary biological aerosols in urban Beijing: size distribution and seasonal variation

Biomass burning and primary biological aerosol particles account for an important part of urban aerosols. Floods of studies have been conducted on the chemical compositions of fine aerosols (PM2.5) in megacities where the haze pollution is one of the severe environmental issues in China. However, little is known about their size distributions in atmospheric aerosols in the urban boundary layer. Here, size-segregated aerosol samples were collected in Beijing during haze and clear days from April 2017 to January 2018. Three anhydrosugars, six primary saccharides and four sugar alcohols in these samples were identified and quantified by gas chromatography/mass spectrometry (GC/MS). Higher concentrations of a biomass burning tracer, levoglucosan, were detected in autumn and winter than in other seasons. Sucrose, glucose, fructose, mannitol and arabitol were more abundant in the bloom and glowing seasons. A particularly high level of trehalose was found in spring, which was largely associated with the Asian dust outflows. Anhydrosugars, xylose, maltose, inositol and erythritol are mainly present in the fine mode (<2.1 µm), while the others showed the coarse-mode preference. The concentrations of measured tracers of biomass burning particles and primary biological particles in the haze events were higher than those in the non-hazy days, with enrichment factors of 2–10. Geometric mean diameters (GMDs) of molecular markers of biomass burning and primary biological aerosols showed that there was no significant difference in the coarse mode (>2.1 µm) between the haze and non-haze samples, while a size shift towards large particles and large GMDs in the fine fraction (<2.1 µm) was detected during the hazy days, which highlights that the stable meteorological conditions with high relative humidity in urban Beijing may favor the condensation of organics onto coarse particles.The contributions of reconstructed primary organic carbon (POC) by tracer-based methods from plant debris, fungal spores and biomass burning to aerosol OC in the total-mode particles were in the ranges of 0.09 %–0.30 % (on average 0.21 %), 0.13 %–1.0 % (0.38 %) and 1.2 %–7.5 % (4.5 %), respectively. This study demonstrates that the contribution of biomass burning was significant in Beijing throughout the whole year with the predominance in the fine mode, while the contributions of plant debris and fungal spores dominated in spring and summer in the coarse mode, especially in sizes >5.8 µm. Our observations demonstrate that the sources, abundance and chemical composition of urban aerosol particles are strongly size dependent in Beijing, which is important to better understand the environmental and health effects of urban aerosols and should be considered in air quality and climate models.