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Diagram displaying atmosphere layers, temperature and airborne emission sources. Yellow line marks atmospheric temperature. Bottom of the figures shows the common sources of aerosolized bacteria, with special attention to dust storms.
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The atmosphere is an extreme environment where organisms are subject to low temperatures and high radiation. Many of the microorganisms detected there appear in resistant forms or show mechanisms of adaptation designed to withstand these extreme conditions. Airborne microorganisms may play an important role in the global climate system, biogeochemi...
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... the ozone layer (between 18 and 35 km into stratosphere), ultraviolet (UV) and cosmic radiation become lethal factors. Once in the mesosphere (above 50 km), life is difficult to imagine; however microorganisms of terrestrial origin could arrive to the stratosphere from lower layers via different phenomena (human activity, thunderstorms, dust storms, or volcanic activity), and bacteria have been found isolated up to 41 km or in dust samples from the International Space Station (Figure 1) [6,29]. Therefore, airborne microbes are always present in the atmosphere [11,30,31], and their permanence is dynamic, resulting in an environment with enormous variability. ...
Citations
... The atmosphere is the largest biome on Earth, but it probably remains the most obscure environment when it comes to microbial functioning (Péguilhan et al., 2023). Atmospheric bacteria are subjected to various environmental stressors, such as UV radiation, extreme temperatures, desiccation, oxygen deficit and lack of nutrients (Aguilera et al., 2018;Chen et al., 2023;Fröhlich-Nowoisky et al., 2016;Lin et al., 2022;Smith et al., 2011). Although the source of atmospheric bacteria is still not fully explained, their origin is likely linked to terrestrial vegetation, soils and bodies of water (Smets et al., 2016). ...
... Researchers in Spain outfitted a CASA-212 turboprop with an air intake on the roof of the aircraft and a filter holder, flow meter, and vacuum pump inside the cabin (Aguilera et al., 2018;González-Toril et al., 2020). The filter holder inside the cabin was designed to be replaced in flight, which could potentially allow for contamination of the sample. ...
... Atmospheric capture of nucleic acids thus far shares similar hurdles to the aquatic realm, including potentially low biomass in an "ocean of air" as well as contamination prevention and assessment, but other challenges also exist for aircraft platforms used in genetic research. For example, achieving isokinetic conditions desired for sampling can be difficult for high velocity aircraft (Aguilera et al., 2018). Contamination is a persistent challenge in aerobiology research (Smith, 2013). ...
... The sampler must be installed on the airplane in a location that avoids chemical contamination from flight operation and is protected from foreign genetic material or cross-contamination (i.e., not from the air being sampled or insects clogging the system, or non-biological particles). Air intakes that are on the fuselage of the aircraft are difficult to sterilize (Aguilera et al., 2018). Ease of cleaning or disinfecting the sampler between runs should be considered to minimize sample contamination (Mainelis, 2020). ...
Air is a medium for dispersal of environmental DNA (eDNA) carried in bioaerosols, yet the atmosphere is mostly unexplored as a source of genetic material encompassing all domains of life. In this study, we designed and deployed a robust, sterilizable hardware system for airborne nucleic acid capture featuring active filtration of a quantifiable, controllable volume of air and a high-integrity chamber to protect the sample from loss or contamination. We used our hardware system on an aircraft across multiple height transects over major aerosolization sources to collect air eDNA, coupled with high-throughput amplicon sequencing using multiple DNA metabarcoding markers targeting bacteria, plants, and vertebrates to test the hypothesis of large-scale genetic presence of these bioaerosols throughout the planetary boundary layer in the lower troposphere. Here, we demonstrate that the multi-taxa DNA assemblages inventoried up to 2,500 m using our airplane-mounted hardware system are reflective of major aerosolization sources in the survey area and show previously unreported airborne species detections ( i.e ., Allium sativum L). We also pioneer an aerial survey flight grid standardized for atmospheric sampling of genetic material and aeroallergens using a light aircraft and limited resources. Our results show that air eDNA from terrestrial bacteria, plants, and vertebrates is detectable up to high altitude using our airborne air sampler and demonstrate the usefulness of light aircraft in monitoring campaigns. However, our work also underscores the need for improved marker choices and reference databases for species in the air column, particularly eukaryotes. Taken together, our findings reveal strong connectivity or mixing of terrestrial-associated eDNA from ground level aerosolization sources and the atmosphere, and we recommend that parameters and indices considering lifting action, atmospheric instability, and potential for convection be incorporated in future surveys for air eDNA. Overall, this work establishes a foundation for light aircraft campaigns to comprehensively and economically inventory bioaerosol emissions and impacts at scale, enabling transformative future opportunities in airborne DNA technology.
... Biological exposures were not always studied from a human-centric perspective. For example, ecologists may be interested in profiling the diversity of microbial species in the air [58], water [59], and land [60]. Still, they are not necessarily concerned about how these diverse microbial species could impact the health of humans or other organisms. ...
Abstract The exposome depicts the total exposures in the lifetime of an organism. Human exposome comprises exposures from environmental and humanistic sources. Biological, chemical, and physical environmental exposures pose potential health threats, especially to susceptible populations. Although still in its nascent stage, we are beginning to recognize the vast and dynamic nature of the exposome. In this review, we systematically summarize the biological and chemical environmental exposomes in three broad environmental matrices—air, soil, and water; each contains several distinct subcategories, along with a brief introduction to the physical exposome. Disease‐related environmental exposures are highlighted, and humans are also a major source of disease‐related biological exposures. We further discuss the interactions between biological, chemical, and physical exposomes. Finally, we propose a list of outstanding challenges under the exposome research framework that need to be addressed to move the field forward. Taken together, we present a detailed landscape of environmental exposome to prime researchers to join this exciting new field.
... Therefore, the two acidophilic plants are classified as calcitolerant and slightly siderophilic ("metal-loving"), but not strongly acidophilic. Several studies have reported that airborne bacteria, fungal spores, pollen grains, and other bioparticles, which are associated with atmospheric dust, survive even at stratospheric altitudes and become active again in their new habitats (Kellogg and Griffin, 2006;Meola et al., 2015;Aguilera et al., 2018;Greilinger et al., 2018). In addition, fragments and propagules of BSCs are likely to be present in the atmosphere and transported long distances by dust storms, potentially acting as a source for the "passive restoration" of soil crusts (Rossi et al., 2017;Warren et al., 2019). ...
There is considerable evidence that mineral dust has an important impact on alpine ecosystems, but the relationship remains unclear in some instances. In an attempt to fill this knowledge gap, we investigated 1) the mineralogical composition of dust components at Hochtor (Hohe Tauern, Austria), 2) its effects on soil formation and biological soil crusts (BSCs), and 3) the effect of mineral dust on plant growth in this interdisciplinary study. Mineral particles such as silicates, carbonates, oxides, volcanic quartz phenocrysts, opaque ore minerals, and spheres, such as microtektites, micrometeorites and fly ash aggregates, were detected using a scanning electron microscope (SEM) equipped with an energy dispersive X-ray spectrometer (SEM-EDX). Rare micrometeorites are of extra-terrestrial origin (cosmic dust) and the decorated spheres are aggregates of fly ashes from anthropogenic origin. In terms of size, fine particles (<100 µm) and coarse particles (>100 µm) characterize the dust composition, originating mainly from adjacent rock outcrops, while the transport from the North African desert appears to be less important and diluted by local sources. The research was carried out as part of the pan-European biodiversity project “Soil Crusts International” (Soil Crust International). The results suggest that mineral dust aids in the rapid formation of BSCs in highly disturbed treated plots, and thus, both fine sand and available phosphorus are statistically proven to be determinants of the rapid growth of biocrusts. The number of plant individuals also increases between 2016 and 2020, however at a relatively moderate rate due to permanent mechanical erosion and debris flow within the treatment plots. Silica dust is believed to be a contributing factor to the widespread distribution of silicate plants in limestone habitats, such as Primula minima and Cerastium uniflorum, two “acidophilic” species that have been tested more closely. Finally, it is deduced that 1) aeolian dust plays a role in the continuous process of soil and crust formation, and 2) it works as a growth regulator in complex biological communities such as BSCs and vascular plant communities by creating new habitats and increasing biodiversity.
... The atmosphere is considered by some to be the 'last extreme environment', due in large part to temperature extremes and high levels of ultraviolet radiation particularly in the upper portions of the earth's atmosphere [120]. Nevertheless, biological material is considered universally present in the atmosphere [121]. ...
Biological soil crusts (BSCs) are created where a diverse array of microorganisms colonize the surface and upper few millimeters of the soil and create a consolidated crust. They were originally described from arid ecosystems where vascular vegetation is naturally sparse or absent. They have since been discovered in all terrestrial ecosystems. Where present, they perform a variety of important ecological functions, including the capture and accumulation of water and essential plant nutrients, and their release in forms useful to vascular plants. They also stabilize the soil surface against wind and water erosion. BSC organisms include fungi (free-living, lichenized, and mycorrhizal), archaea, bacteria (cyanobacteria and chemotrophic and diazotrophic bacteria), terrestrial algae (including diatoms), and bryophytes (mosses and worts). BSC organisms reproduce primarily asexually via thallus or main body fragmentation or production of asexual spores that are readily dispersed by water and wind. Asexual and sexual propagules of BSC organisms are commonly lifted into the air with vast quantities of dust from the world's arid areas. BSC organisms and/or their propagules have been detected as high as the stratosphere. Some have also been detected in the mesosphere. Airborne dust, microorganisms, and their propagules contribute to the formation of essential raindrop and snowflake nuclei that, in turn, facilitate precipitation events. While airborne in the atmosphere, they also reflect the sun's rays passing laterally through the troposphere and stratosphere at dawn and dusk, often causing brilliant colors at sunrise and sunset.
... Aquatic diatoms are generally dispersed by water currents. However, terrestrial diatoms (e.g., vegetative cells and auxospores) are typically dispersed through the atmosphere under very dry conditions (Sharma and Singh, 2010;Aguilera et al., 2018). Research has shown that diatoms can reach the atmosphere in various ways including volcanic eruptions (Pike, 2013;Van Eaton et al., 2013) and dust and sand storms (Griffin et al., 2002). ...
Biological soil crusts (BSCs) consist of a diverse and highly integrated community of organisms that effectively colonize and collectively stabilize soil surfaces. BSCs vary in terms of soil chemistry and texture as well as the environmental parameters that combine to support unique combinations of organisms—including cyanobacteria dominated, lichen-dominated, and bryophyte-dominated crusts. The list of organismal groups that make up BSC communities in various and unique combinations include—free living, lichenized, and mycorrhizal fungi, chemoheterotrophic bacteria, cyanobacteria, diazotrophic bacteria and archaea, eukaryotic algae, and bryophytes. The various BSC organismal groups demonstrate several common characteristics including—desiccation and extreme temperature tolerance, production of various soil binding chemistries, a near exclusive dependency on asexual reproduction, a pattern of aerial dispersal over impressive distances, and a universal vulnerability to a wide range of human-related perturbations. With this publication, we provide literature-based insights as to how each organismal group contributes to the formation and maintenance of the structural and functional attributes of BSCs, how they reproduce, and how they are dispersed. We also emphasize the importance of effective application of molecular and microenvironment sampling and assessment tools in order to provide cogent and essential answers that will allow scientists and land managers to better understand and manage the biodiversity and functional relationships of soil crust communities.
