Ground level environmental protein concentrations in various ecuadorian environments: Potential uses of aerosolized protein for ecological research

Large quantities of free protein in the environment and other bioaerosols are ubiquitous throughout terrestrial ground level environments and may be integrative indicators of ecosystem status. Samples of ground level bioaerosols were collected from various ecosystems throughout Ecuador, including pristine humid tropical forest (pristine), highly altered secondary humid tropical forest (highly altered), secondary transitional very humid forest (regrowth transitional), and suburban dry montane deforested (suburban deforested). The results explored the sensitivity of localized aerosol protein concentrations to spatial and temporal variations within ecosystems, and their value for assessing environmental change. Ecosystem specific variations in environmental protein concentrations were observed: pristine 0.32 ± 0.09 μg/m³, highly altered 0.07 ± 0.05 μg/m³, regrowth transitional 0.17 ± 0.06 μg/m³, and suburban deforested 0.09 ± 0.04 μg/m³. Additionally, comparisons of intra-environmental differences in seasonal/daily weather (dry season 0.08 ± 0.03 μg/m³ and wet season 0.10 ± 0.04 μg/m³), environmental fragmentation (buffered 0.19 ± 0.06 μg/m³ and edge 0.15 ± 0.06 μg/m³), and sampling height (ground level 0.32 ± 0.09 μg/m³ and 10 m 0.24 ± 0.04 μg/m³) demonstrated the sensitivity of protein concentrations to environmental conditions. Local protein concentrations in altered environments correlated well with satellite-based spectral indices describing vegetation productivity: normalized difference vegetation index (NDVI) (r² = 0.801), net primary production (NPP) (r² = 0.827), leaf area index (LAI) (r² = 0.410). Moreover, protein concentrations distinguished the pristine site, which was not differentiated in spectral indices, potentially due to spectral saturation typical of highly vegetated environments. Bioaerosol concentrations represent an inexpensive method to increase understanding of environmental changes, especially in densely vegetated ecosystems with high canopies or in areas needing high spatial and temporal resolution. Further research to expand understanding of the applicability of bioaerosol concentrations for environmental monitoring is supported by this pilot study.     

A comparison of airborne and dust-borne allergens and toxins collected from home,office and outdoor environments both in New Haven,United States and Nanjing,China

In this study, the airborne and dust-borne concentrations of endotoxin, (1,3)-β-d-glucan and five house dust allergens were measured in office, home, and outdoor environments both in New Haven, United States and Nanjing, China. Air samples were collected using a BioSampler at a flow rate of 12.5 l/min for 30 min. Dust samples were simultaneously collected using a surface sampler. Dust samples went through extraction and dilution before analysis, while air samples were analyzed directly. Limulus Amoebocyte Lysate (LAL) Pyrochrome and Glucatell assays were used to quantify endotoxin and (1,3)-β-d-glucan concentration levels, respectively. Enzyme-linked sorbent assay was used to measure the dust mites, cat, dog, and cockroach allergens. The experimental results indicated that endotoxin, (1,3)-β-d-glucan and allergen concentrations vary greatly both with samples and environments. In all tested environments, endotoxin concentration ranged from 0.8 to 83.7 ng/m³ for air, and 7.8 to 14.3 ng/mg for dust. (1,3)-β-d-glucan concentration ranged from 0.1 to 9.8 ng/m³ for air, and 6.6 to 110 ng/mg for dust. Cockroach allergens were detected only in New Haven office and outdoor environments, and other allergens ranged from 0.1 to 90 ng/mg for dust samples, and from 1.5 to 1,282 ng/m³ for air samples. In general, similar profiles of allergens and toxins were observed in New Haven and Nanjing environments. Linear regression analysis showed that there were better endotoxin and (1,3)-β-d-glucan linear correlations (R ² = 0.78, 0.87, respectively) between the dust and air samples compared to those of the allergens Der f 1 and Der p 1 (R ² = 0.5, 0.7, respectively). This research contributes to the development of robust biological exposure assessment and the elaboration of airborne and dust-borne bio-mass in the living environments.     

The Dry Aerosol Deposition Device (DADD): An instrument for depositing microbial aerosols onto surfaces

Concerns surrounding the contamination of infrastructure and equipment with biowarfare agents have led to the development of antimicrobial surfaces/coatings that are designed to “self-sterilize.” Surfaces will likely be contaminated via an aerosol exposure and thus antimicrobial efficacy measurements should also be performed using biological aerosols. Standard methods that use microbial agents suspended in aqueous buffers may provide misleading results that overestimate the performance of the surface. A settling chamber is the most common instrument for applying biological aerosols to surfaces. However, settling chambers have some drawbacks (e.g., slow loading times, large footprint, variable loading, etc.) that make them undesirable for many applications. We have developed a Dry Aerosol Deposition Device (DADD) that uses impaction rather than settling to load surfaces with biological aerosols. The use of impaction allows for rapid and highly reproducible loading of microorganisms onto surfaces. We have demonstrated that the DADD can deliver both Bacillus atrophaeus spores and Staphylococcus aureus vegetative cells to glass coupons at concentrations exceeding 1 × 10⁴ CFU/cm². The average coefficient of variation (CV) for sample-to-sample loading within an experiment was 13.6% for spores and 6.1% for S. aureus cells. The DADD is also a relatively simple and inexpensive device that can easily be contained within a 4-foot biological safety cabinet.     

A DNA aptamer recognizes the Asp f 1 allergen of Aspergillus fumigatus

Allergies are caused by the binding of IgE antibodies onto specific sites on allergens. However, in the assessment of exposure to airborne allergens, current techniques such as whole spore counts fail to account for the presence of these allergenic epitopes that trigger allergic reactions. The objective of the research is to develop a DNA aptamer for the Asp f 1 allergen of the pathogenic fungus Aspergillus fumigatus, using an IgE-binding epitope of the allergen as the target for aptamer selection. Through in vitro SELEX, an aptamer has been produced that binds with nanomolar affinity to the Asp f 1 IgE-epitope. The aptamer is also able to recognize the native Asp f 1 allergen, and does not bind to allergenic proteins from non-target mold species such as Alternaria alternata. Production of this aptamer provides proof-of-principle that allergen measurement methods can be developed to indicate the potent fraction, or allergenicity, of allergens.     

DNA aptamers bind specifically and selectively to (1 → 3)-β-d-glucans

(1 → 3)-β-d-Glucans are structural cell wall components of fungi, plants, and some bacteria and have been linked with human respiratory symptoms following aerosol exposure. A clear interpretation of the health impact of (1 → 3)-β-d-glucans is limited by the high cost and uncertainties associated with current glucan quantitation methods. The objective of this research is to develop DNA aptamers for the measurement of (1 → 3)-β-d-glucans. Aptamers are synthetic DNA functional binding molecules that fold into unique conformations, allowing them to bind specifically to their target. Through the in vitro selection process SELEX, we have produced aptamers that are able to bind with sub-micromolar affinity to curdlan, a linear unbranched form of (1 → 3)-β-d-glucans. These aptamers display high selectivity to curdlan and do not bind to non-(1 → 3)-β-d-polysaccharides, suggesting specificity for the β-(1 → 3)-glycosidic linkage. The aptamers produced here will enable the production of more cost-effective, less ambiguous assays for the environmental measurement of (1 → 3)-β-d-glucans.     

Detection of Jeotgalicoccus spp. in poultry house air

Investigations of bioaerosols collected from turkey, chicken and duck houses, as well as from a duck slaughterhouse, each in triplicate, revealed that 4–18% of 16S rRNA gene sequences in investigated 16S rRNA gene clone libraries were closely related to Jeotgalicoccus spp. J. halotolerans- and J. psychrophilus-related sequences were obtained in all investigated bioaerosol samples and formed a distinct group with sequences of both species type strains, which were collectively entitled Jeot-cluster-I. For a quantification of Jeot-cluster-I bacteria, a group specific PCR primer combination targeting the 16S rRNA genes was developed. Estimated concentrations by quantitative real-time PCR analyses revealed cell numbers between 10⁴ and 10⁶ Jeotgalicoccus cells m⁻³ air in turkey, duck, and chicken houses, respectively. These results indicated the remarkable proportion (1–39%) of total cell counts and the hitherto unknown wide distribution of Jeotgalicoccus spp. in the poultry rearing industry.     

A comparison between computer modeled bioaerosol dispersion and a bioaerosol field spray event

The observed deposition pattern from a field spray ofBacillus subtilus var.niger spores is compared with that of a computer simulated bioaerosol particle dispersion model. Using the same meteorological conditions as the field spray, the model produced a bioaerosol deposition pattern estimated to be reasonably similar (R ²=0.66) to the observed field pattern. Reasons for the differences between the deposition patterns are discussed. The comparison indicates that viable airborne particle deposition models may, with future testing, be useful tools for predicting near source aerial microbial dispersal and deposition. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.     

Qualitative and quantitative methodologies for determination of airborne microorganisms at concentrated animal-feeding operations

The generation of airborne microorganisms from concentrated animal-feeding operations (CAFOs) is a concern from a human and animal health perspective. To better understand the airborne microorganisms found in these environments, a number of collection and analytical techniques have been utilized and will be discussed in this review. The most commonly used bioaerosol collection method is the liquid impingement format, which is suitable with a number of culture-based and non-culture molecular-based approaches, such as polymerase chain reaction. However, the vast majority of airborne microorganism studies conducted at CAFOs utilize culture-based analyses. Because of the limitations often associated with culture-based analyses, we focused our discussion on the application of molecular-based techniques to identify and/or quantify microorganisms, as they have promising application in bioaerosol research. The ability to rapidly characterize airborne microorganisms will help to ensure protection of public and environmental health. The use or mention of any commercial products does not imply any endorsement of that product by either the authors or the US Department of Agriculture.     

Effects of humidity and other factors on the generation and sampling of a coronavirus aerosol

Suspensions of transmissible gastroenteritis virus (TGEV), a porcine coronavirus, were nebulized at rates of 0.1–0.2 ml/min into moving air using a Collison nebulizer or a plastic medical nebulizer operating at pressures ranging from 7 to 15 psi. The airborne viruses were collected on heating, ventilating, and air conditioning (HVAC) filters in an experimental apparatus and also sampled upstream of these test filters using AGI-30 and BioSampler impinger samplers. To study the effects of relative humidity (RH) on TGEV collection by the filters and samplers, the virus was nebulized into air at 30, 50, 70, and 90% RH. There were no significant changes in virus titer in the nebulizer suspension before and after nebulization for either nebulizer at any of the pressures utilized. Aerosolization efficiency – the ratio of viable virus sampled with impingers to the quantity of viable virus nebulized – decreased with increasing humidity. BioSamplers detected more airborne virus than AGI-30 samplers at all RH levels. This difference was statistically significant at 30 and 50% RH. Nebulizer type and pressure did not significantly affect the viability of the airborne virus. Virus recovery from test filters relative to the concentration of virus in the nebulizer suspension was less than 10%. The most and the least virus were recovered from filter media at 30% and 90% RH, respectively. The results suggest that TGEV, and perhaps other coronaviruses, remain viable longer in an airborne state and are sampled more effectively at low RH than at high humidity.