Microbial functional signature in the atmospheric boundary layer

Abstract

Abstract. Microorganisms are ubiquitous in the atmosphere and some airborne microbial cells were shown to be particularly resistant to atmospheric physical and chemical conditions (e.g., UV radiation, desiccation, presence of radicals). In addition to surviving, some cultivable microorganisms of airborne origin were shown to be able to grow on atmospheric chemicals in laboratory experiments. Metagenomic investigations have been used to identify specific signatures of microbial functional potential in different ecosystems. We conducted a preliminary comparative metagenomic study on the overall microbial functional potential and specific metabolic and stress-related microbial functions of atmospheric microorganisms in order to determine whether airborne microbial communities possess an atmosphere-specific functional potential signature as compared to other ecosystems (i.e. soil, sediment, snow, feces, surface seawater etc.). In absence of a specific atmospheric signature, the atmospheric samples collected at nine sites around the world were similar to their underlying ecosystems. In addition, atmospheric samples were characterized by a relatively high proportion of fungi. The higher proportion of sequences annotated as genes involved in stress-related functions (i.e. functions related to the response to desiccation, UV radiation, oxidative stress etc.) resulted in part from the high concentrations of fungi that might resist and survive atmospheric physical stress better than bacteria.

Functional Genes Profile of Atmospheric Dust in the East Mediterranean Suggests Widespread Anthropogenic Influence on Aerobiome Composition

“…Previous studies on atmospheric metagenome tried to determine whether a preselected set of genes were significantly enriched in atmospheric samples compared with other environments. The genes of choice were mainly associated with stress resistance (Aalismail et al., 2019; Tignat‐Perrier, Dommergue, Thollot, Magand, Vogel, et al., 2020) and metabolism of compounds present in the atmosphere (Amato et al., 2019). Thus, the relative abundance of each gene was tested individually and, in some cases, compared to other environments.…”

“…Fewer studies on the aerobiome have collected sufficient material to obtain the DNA concentrations required for metagenomic and metatranscriptomic sequencing. These studies explored different anthropogenic environments, such as farms and cities (Be et al., 2014; Cao et al., 2014; Tringe et al., 2008; Yooseph et al., 2013), natural environments in various geographic locations (Tignat‐Perrier, Dommergue, Thollot, Magand, Vogel, et al., 2020), and different aerosol types, for example, cloud‐condensation droplets (Amato et al., 2019) and atmospheric dust (Aalismail et al., 2019; Peng et al., 2021). The studies provided preliminary insights into the aerobiome's potential functions.…”

The Biogeography of Dust in the Eastern Mediterranean

“…12,64,66,67 Recent studies suggest that aerosol microbiomes are most affected by the microbiomes of underlying environments. 19,64,68 Variations over seasons and in airmass origin were also linked to changes in aerosol microbial community composition. 1,2,6,9,69,70 The aerobiome community composition displays mixtures of sources, and detecting a constant and stable indigenous microbial community was not yet reported.…”

“…Dust is a well-recognized vector for the long-range microbial transport of microorganisms and pollution. 12,64,66,67 Recent studies suggest that aerosol microbiomes are most affected by the microbiomes of underlying environments. 19,64,68 Variations over seasons and in airmass origin were also linked to changes in aerosol microbial community composition.…”

“…Previous studies have suggested that the adaptation of airborne microorganisms to atmospheric conditions would bene t from the presence of functions such as UV resistance, osmotic stress resistance, envelope stress resistance, sporulation, methane oxidation, formate degradation, acetic acid degradation and oxidative stress resistance. 3,8,64,65 Thus, these studies targeted these functions in metagenomic as well as metatranscriptomic analyses of different atmospheric samples. Consistent with this, we focused on these functional genes, as well as many other environmentally relevant functional genes, in our analysis to better de ne the contribution of mineral dust to the potential functionality of the aerobiome.…”