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Sign In. Advanced Search. Search Menu. Article Navigation. Close mobile search navigation Article Navigation. Volume Article Contents Abstract. The atmosphere. Airborne microbial biodiversity. Aerial growth and survival. Airborne microbial activity. Aerial dispersal and colonization. Life at the edge. Airborne microorganisms and climate change. Microorganisms in the atmosphere over Antarctica. Pearce , David A. Correspondence: David A. Oxford Academic. Paul D. Kevin A. Birgit Sattler.
Roland Psenner. Nick J. Editor: Ian Head. Revision received:. Cite Cite David A. Select Format Select format. Permissions Icon Permissions. Abstract Antarctic microbial biodiversity is the result of a balance between evolution, extinction and colonization, and so it is not possible to gain a full understanding of the microbial biodiversity of a location, its biogeography, stability or evolutionary relationships without some understanding of the input of new biodiversity from the aerial environment.
Antarctica , aerobiology , aerial , polar , atmosphere. Open in new tab Download slide. The Antarctic troposphere. Open in new tab. Microflora of central Antarctic glacier and methods for sterile ice-core sampling for microbiological analyses. Google Scholar Crossref. Search ADS. Ice-nucleation negative fluorescent pseudomonads isolated from Hebridean cloud and rain water produce biosurfactants.
The sea surface microlayer as a source of viral and bacterial enrichment in marine aerosols. New directions:the role of bioaerosols in atmospheric chemistry and physics. The broad-scale distribution of microfungi in the Windmill Islands region continental Antarctica. The contribution of bacteria and fungal spores to the organic carbon content of cloud water precipitation and aerosols.
Also people tend to stay inside more during the winter season, forcing us to breath in stuffy rooms shared by many other people. Airborne microbes are biological airborne contaminants also known as bioaerosols like bacteria, viruses or fungi as well as airborne toxins passed from one victim to the next through the air, without physical contact, causing irritation at the very least Earth Materials and Health, pg.
This usually happens when an infected subject sneezes, coughs, or just plain breathes. It is hard to prevent such a method of transmission. Airborne microbes are a major cause of respiratory ailments such as allergies and pathogenic infections virus or bacteria. In order to educate you about airborne microbes in different environments, I will let you know a little bit about when, where and how you can find these little, microscopic buggers and what kind of affect they'll have on you or your family.
Everyone has their own natural microorganisms that live on, in and around their own bodies. These bacteria are known as natural flora and our own bodies specifically the immune system recognize that they are good for us. We, as humans, would not survive without such creatures. However, this website gives information regarding pathogenic microorganisms in general. That is, things that you can't see causing physical harm. One example of an airborne toxin is called endotoxin or lipopolysaccharide which may be one of the most important human allergens Earth Materials and Health, pg.
Endotoxin is continually released from the cell wall of a gram negative bacteria during bacterial the Gram-negative kinds cell growth and decay. When comparing a gram-negative bacteria to a gram-positive, negative are more resistant against antibodies, because of their outer membrane, which the positive lack. These bacteria exist in soils and can be aerosolized; driving a tractor across a field on a dry day is a good example of causing high exposure to endotoxin.
Fierer et al. Patient room airborne bacterial sampling conducted by Kembel et al. The influence of environmental factors temperature, RH, air exchange rate, and occupant density on bacterial abundance in the air has been reported by some studies, but a general relationship has not been confirmed.
All of these observations support the proposal that microbiome data collection should be accompanied by the measurement of physicochemical factors, such as temperature, humidity, air exchange rate, and occupant density.
Humans are constantly exposed to environmental microbes that can impact their microbiome. Here, we reviewed the sources of bacteria and the factors influencing the airborne bacterial communities and concentration in built environments.
Bacteria in these spaces originate from different sources, and their communities are directly and indirectly affected by physical factors such as temperature and humidity. It is now clear that fungal aerosols can cause human disease, and guidelines for fungi in indoor air have existed since reviewed by Rao et al.
Moreover, many countries, including the United States, Canada, and France, have established humidity standards for indoor environments because humidity significantly affects the growth of common fungi linked to allergies and breathing problems. China and South Korea have established air quality standards in buildings Kim et al. Brazil, Hong Kong, and Singapore have already regulated the concentrations of airborne microorganisms in indoor environments.
Given the health risks posed by airborne microorganisms, which are easily transmitted to different areas, it is important to note that the built environment equates to the sum total of all the assembled items that surround us, both natural and man-made.
By understanding the effects of temperature, RH, air exchange rate, and occupant density on microbial communities in built-up areas, we can design healthier living spaces in future. Ramos and Stephens , Glass et al. Therefore, in line with other researchers, we recommend the routine measurement of four environmental factors temperature, RH, air exchange rate, and occupant density to assess airborne bacteria in built environments, as a minimum requirement.
By improving data collection, we can begin to understand the airborne bacteria environment of the built environment in more detail as a meta-community. This knowledge will provide insights into the relationship between humans and bacterial communities in this environment, and will help improve our air quality of life.
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Adams, R. Ten questions concerning the microbiomes of buildings. C , — Chamber bioaerosol study: outdoor air and human occupants as sources of indoor airborne microbes.
Adar, S. The respiratory microbiome: an underappreciated player in the human response to inhaled pollutants? Afshinnekoo, E. Geospatial resolution of human and bacterial diversity with city-scale metagenomics. Cell Syst. Aydogdu, H. Indoor and outdoor airborne bacteria in child day-care centers in Edirne City Turkey , seasonal distribution and influence of meteorological factors. The ecology of microscopic life in household dust.
B Blaser, M. Bouillard, L. Bacterial contamination of indoor air, surfaces, and settled dust, and related dust endotoxin concentrations in healthy office buildings. PubMed Abstract Google Scholar. Bowers, R. Seasonal variability in bacterial and fungal diversity of the near-surface atmosphere. Spatial variability in airborne bacterial communities across land-use types and their relationship to the bacterial communities of potential source environments.
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Cardini, U. Microbial dinitrogen fixation in coral holobionts exposed to thermal stress and bleaching. Chan, C. Air pollution in mega cities in China. Chase, J. Geography and location are the primary drivers of office microbiome composition. Cole, J. Sediment microbial communities in Great Boiling Spring are controlled by temperature and distinct from water communities. Dannemiller, K. Influence of housing characteristics on bacterial and fungal communities in homes of asthmatic children.
Indoor Air 26, — Fungal and bacterial growth in floor dust at elevated relative humidity levels. Indoor Air 27, — Dillon, H. Review of methods applicable to the assessment of mold exposure to children. Health Perspect. Dong, L. Concentration and size distribution of total airborne microbes in hazy and foggy weather.
Total Environ. Species assemblages and indicator species:the need for a flexible asymmetrical approach. Dunn, R. Home life: factors structuring the bacterial diversity found within and between homes. Eckburg, P. Diversity of the human intestinal microbial flora. Science , — Elin, R. Workload, space, and personnel of microbiology laboratories in teaching hospitals.
Fabian, M. Ambient bioaerosol indices for indoor air quality assessments of flood reclamation. Aerosol Sci. Fahlgren, C. Annual variations in the diversity, viability, and origin of airborne bacteria. Fang, Z. Profile and characteristics of culturable airborne bacteria in hangzhou, Southeast of China. Air Quality Res. Fierer, N. Short-term temporal variability in airborne bacterial and fungal populations.
Frankel, M. Seasonal variations of indoor microbial exposures and their relation to temperature, relative humidity, and air exchange rate. Fujimura, K. House dust exposure mediates gut microbiome Lactobacillus enrichment and airway immune defense against allergens and virus infection. Glass, E. Grice, E. The skin microbiome. Hasegawa, K. Indoor environmental problems and health status in water-damaged homes due to tsunami disaster in Japan.
Heo, K. Effects of human activities on concentrations of culturable bioaerosols in indoor air environments. Hewitt, K. Office space bacterial abundance and diversity in three metropolitan areas. Hoge, C. An epidemic of pneumococcal disease in an overcrowded, inadequately ventilated jail. Hoisington, A. The microbiome of the built environment and mental health. Microbiome Characterizing the bacterial communities in retail stores in the United States. Honda, K. A possible solution to the low biomass of the atmosphere is to increase sampling time, but in the case of flights, we are limited to the flight autonomy of the aircraft.
Although scarce, some studies from airplanes have been conducted. The first studies that were conducted in airplanes were carried out by impaction on a petri plate with enrichment means, which allowed isolating microorganisms from the upper troposphere and even from the stratosphere [ 21 , 57 , 60 ].
However, advances in molecular ecology have caused the most recent studies to favor filtration [ 40 , 58 ]. The European Facility for Airborne Research EUFAR program brings together infrastructure operators of both instrumented research aircraft and remote sensing instruments with the scientific user community. However, it lacked aircraft prepared for microbiological sampling.
Now, these two aircraft are a unique tool for the study of atmospheric microbial diversity and the different environments of the EUFAR program. Our research group has a CASA aircraft with an air intake located on the roof of the aircraft. A metal tube fits the entrance and is fitted inside the aircraft to a filter holder, a flowmeter, and a pump Figure 3. This simple system is easy to sterilize, and both the metal tube and the filter holder can be replaced in flight by other sterile ones if we want to take different samples.
Using PM10 fiberglass filters, we can obtain isokinetic conditions and pass L of air per hour through the filter, as indicated by the flowmeter. In a series of recent experiments, we tried to install a multi-sampler system in our aircraft, where we had five systems in parallel and connected to the same intake of the plane: one filter holder, two impingement systems, and two impactors Figure 4.
The results clearly showed that in the case of our aircraft, filtration was more efficient data not shown. A Impinger sampler, design and manufacture own. Aerobiology studies have traditionally focused on the collection of bacterial cells and the analysis of samples by total counting and culture-based techniques.
It is known that such methods capture only a small portion of the total microbial diversity [ 61 ]. The almost exclusive use, for years, of these methodologies is one of the reasons for these limitations in the knowledge of aerobiology.
In addition, culture-dependent methods do not allow us to study the interactions between different species of microorganisms.
Culture-independent methods have been used to assess microbial diversity, increasing the specificity of microbial identification and the sensitivity of environmental studies, especially in extreme environments. These methods have recently been applied to various areas of airborne microbiology [ 62 , 63 , 64 , 65 ] revealing a greater diversity of airborne microorganisms when compared to culture-dependent methods. Some good studies approach the challenges and opportunities of using molecular methodologies to address airborne microbiology [ 20 , 66 ].
Although molecular ecology methods allow the rapid characterization of the diversity of complex ecosystems, the isolation of the different components is essential for the study of their phenotypic properties in order to evaluate their role in the system and their biotechnological potential. A combination of culture-dependent and culture-independent methods is ideal to address the complete study of the system.
Modern culture-independent approaches to community analysis, for example, metagenomics and individual cell genomics, have the potential to provide a much deeper understanding of the atmospheric microbiome. However, molecular ecology techniques face several particular challenges in the case of the atmospheric microbiome: 1 very low biomass [ 20 ]; 2 inefficient sampling methods [ 20 ]; 3 lack of standard protocols [ 9 , 20 ]; 4 the composition of airborne microbes continuously changes due to meteorological, spatial, and temporal patterns [ 7 , 62 , 67 , 68 , 69 , 70 ]; and 5 avoidance of the presence of foreign DNA in the system [ 59 ].
Because these issues are not yet resolved, most of the non-culturing approaches focus on microbial diversity, where they are highly efficient. Often, this approach is more efficient due to the greater efficiency and sensitivity of this process, as opposed to gene cloning and Sanger sequencing; thus some authors are inclined toward metagenomics instead of amplification. This provides more information and avoids an intermediate step, but bioinformatic processing is tedious and often only provides data in relation to diversity, making the annotation of the rest of the information very complicated [ 20 ].
These approaches can be complemented with quantitative methods such as qPCR, flow cytometry, or fluorescence in situ hybridization FISH [ 41 , 47 , 66 , 71 ]. FISH is surely the best and most specific cell quantification methodology that exists. However, in the case of aerobiology, it cannot always be used.
A minimum number of cells must exist so that we can observe and count them under a fluorescence microscope. Due to the variability of microbial populations in the air, this is not always achieved.
In our research group, we have obtained very good results in this regard, optimizing cell concentration. Figure 5 shows epifluorescence micrographs of bacteria from an air sample. Sampling was conducted for 2 hours at ground level, pumping a total of 36, L of air. After this time, the sample was paraformaldehyde fixed and filtered through a 0. The second half was hybridized with the probe NON [ 74 ] as negative control.
In this case, an average of cells per liter of air was counted. Epifluorescence micrographs of bacteria from an air sample. All micrographs correspond to the same hybridization process, performed with a sample obtained after 4 hours sampling at ground. C and D show microorganisms attaches to a mineral particles arrow sign. DNA gives us much information about the diversity of the system, but if we wish to obtain information about the metabolic activity that is taking place in the ecosystem, metabolomic and metatranscriptomic approaches are needed [ 50 , 66 ].
In the case of the atmosphere, this is crucial, since we are not fully certain if the cells present are active. Some studies indicate that a part of the microorganisms in the atmosphere are developing an activity [ 6 ], but until we conduct RNA-based and metabolite-based studies, we will not have the certainty that this is the case. The big problem is that it is very difficult to carry out these studies using the current microbial capture systems. Scanning electron microscopy SEM also provides much information of the aerobiology [ 7 ].
Specifically, it allows the characterization of eukaryotic cells e. Figure 6A shows pine tree pollen observed via SEM in a sample obtained after a 30 minutes flight of the C aircraft. SEM images of different airborne samples. A Pinus pollen. Ground sample after 2 hours sampling. B Air sample collected from C aircraft during a Saharan dust intrusion February 24, Filter appear completely cover of mineral particles.
B and C Biological particles sampled using C aircraft. E Diatomea sampled by C aircraft in a fligth along the northern coast of Spain 9 March F Cell attached to mineral particles and organic matter. As mentioned above, factors, such as the shortage of nutrients and substrates, high UV radiation, drying, changes in temperature and pH, or the presence of reactive oxygen species, make the atmosphere an extreme environment.
However, it is possible that the high variability of its conditions is the one characteristic that makes this environment more extreme [ 1 , 20 ].
Among the cells present in the atmosphere, a considerable portion appears in the resistance forms capable of withstanding low-temperature and high-radiation conditions. This is what probably happens with fungi and gram-positive bacteria. Bacillus strains recurrently isolated from the atmosphere have characteristics and a capacity to sporulate very similar to strains isolated from the soil.
Undoubtedly, another part of the cells will be in the form of latency and may even suffer modifications of the cell wall and slow down or stop their metabolic activity [ 75 , 76 ]. These transformations can improve resistance to physical stresses, such as UV radiation [ 58 ].
On the other hand, some of the bacteria present in the atmosphere, such as Geodermatophilus , show pigmentation that undoubtedly protects it from excessive radiation. The microorganisms that are usually detected in the atmosphere originate mainly from the soil, which means they will share similar mechanisms of resistance. In some strains, metabolic adaptations have been observed to lack nutrients such as cytochrome bd biosynthesis to survive iron deprivation [ 77 ]. Deinococcus is also a recurrent genus in the atmosphere, which, like those in soil, has multiresistance mechanisms based on high DNA-repair efficiency.
Another strategy of resistance could be cell clustering and adhesion to particles.
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