Spatiotemporal patterns of microbial composition and diversity in precipitation

Aho, Ken; Weber, Carolyn F.; Christner, Brent C.; Vinatzer, Boris A.; Morris, Cindy E.; Joyce, Rachel E.; Failor, Kevin C.; Werth, Jason T.; Bayless‐Edwards, Aurora L. H.; Schmale, David G.

doi:10.1002/ecm.1394

Cited by 16 publications

(12 citation statements)

References 121 publications

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“…When compared to low intensity rainfall, moderately intense rainfall produces larger drop sizes, which tend to be more efficient at scavenging below-cloud aerosols (Figure 4). Our results are consistent with recent observations showing the fungal composition of rain correlated with lower altitude characteristics of storms, whereas the smaller-sized bacteria assemblages correlated with macroscale drivers that implied nonlocal sources [45]. It should be noted our calculations have ignored the contribution of microbial aerosols within the cloud that are subject to scavenging as drops descend through the cloud.…”

Section: Discussionsupporting

confidence: 90%

Scavenging of Sub-Micron to Micron-Sized Microbial Aerosols during Simulated Rainfall

et al. 2020

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The processes removing aerosols from the atmosphere during rainfall are generically referred to as scavenging. Scavenging influences aerosol distributions in the atmosphere, with consequent effects on cloud properties, radiative forcing, and human health. In this study, we investigated the below-cloud scavenging process, specifically focusing on the scavenging of 0.2 to 2 µm-sized microbial aerosols by populations of water drops with average diameters of 3.0 and 3.6 mm. Rainfall was simulated in convective boundary layer air masses by dispensing the water drops from a 55 m bridge and collecting them at ground level. Particles and microbial cells scavenged by the water drops were visualized, enumerated, and sized using scanning electron and epifluorescence microscopy. Aerosolized particles and DNA-containing microbial cells of 2 µm diameter were scavenged at efficiencies similar to those reported previously in empirical studies; however, the efficiencies derived for smaller aerosols were significantly higher (one to three orders of magnitude) than those predicted by microphysical modeling. Application of the derived scavenging efficiencies to cell data from rainfall implies that, on average, approximately 50 to 70% of the 1 µm microbial cells in the precipitation originated from within the cloud. Further study of submicron to micron-sized aerosol scavenging over a broader raindrop size distribution would improve fundamental understanding of the scavenging process and the capacity to estimate (bio)aerosol abundances in the source cloud through analysis of rainfall.

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Section: Discussionsupporting

confidence: 90%

Scavenging of Sub-Micron to Micron-Sized Microbial Aerosols during Simulated Rainfall

et al. 2020

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“…Similarly, another study showed that diurnal cycles in the boundary layer resulted in fungal and bacterial aerosols shifting with temperature, humidity, and CO 2 conditions 48 . Both dry and wet deposition significantly influence bioaerosol patterns and it is worth emphasizing our flights occurred in non-cloudy, precipitation-free areas 49 . With a multiyear campaign lasting seven years at an alpine field site in Spain, dynamic, seasonal shifts in 16S rRNA measurements (yielding mostly Alphaproteobacteria and Betaproteobacteria) were found 4 .…”

Section: Discussionmentioning

confidence: 99%

Sierra Nevada sweep: metagenomic measurements of bioaerosols vertically distributed across the troposphere

Jaing

Thissen

Morrison

et al. 2020

Sci Rep

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To explore how airborne microbial patterns change with height above the Earth's surface, we flew NASA's C-20A aircraft on two consecutive days in June 2018 along identical flight paths over the US Sierra Nevada mountain range at four different altitudes ranging from 10,000 ft to 40,000 ft. Bioaerosols were analyzed by metagenomic DnA sequencing and traditional culturing methods to characterize the composition and diversity of atmospheric samples compared to experimental controls. The relative abundance of taxa changed significantly at each altitude sampled, and the diversity profile shifted across the two sampling days, revealing a regional atmospheric microbiome that is dynamically changing. the most proportionally abundant microbial genera were Mycobacterium and Achromobacter at 10,000 ft; Stenotrophomonas and Achromobacter at 20,000 ft; Delftia and Pseudoperonospora at 30,000 ft; and Alcaligenes and Penicillium at 40,000 ft. Culturebased detections also identified viable Bacillus zhangzhouensis, Bacillus pumilus, and Bacillus spp. in the upper troposphere. to estimate bioaerosol dispersal, we developed a human exposure likelihood model (7-day forecast) using general aerosol characteristics and measured meteorological conditions. By coupling metagenomics to a predictive atmospheric model, we aim to set the stage for field campaigns that monitor global bioaerosol emissions and impacts. Aerosols (mostly desert dust, black carbon and ocean spray) regularly disperse across the Pacific Ocean with springtime atmospheric winds-in fact, models suggest that as much as 64 Teragrams of Asian aerosols can be transported to North America annually 1. Past studies have reported microorganisms co-transported with globally-dispersed aerosols, and that both DNA signatures and viable cells can be detected in air masses 2-4. For example, thousands of taxonomic signatures were measured in springtime Asian dust plumes delivering free tropospheric bioaerosols to an alpine research station in central Oregon 3. In a separate flight project surveying airborne microorganisms in the western region of the United States, several taxa were found to be enriched in the upper atmosphere, including bacterial families Lachnospiraceae, Ruminococcaceae and Erysipelotrichaceae 2. Despite harsh conditions in the atmosphere, viable bacterial isolates were recovered from the same study 2 , including Bacillus sp., Micrococcus sp., Arthrobacter sp. and Staphylococcus sp. Previous aerobiology campaigns using aircraft were flown at single altitudes in order to refine collection methods and demonstrate some of the first measurements of an atmospheric microbiome 2,5-7. To date, there are only a few studies that have examined microbiological changes across a vertical gradient in Earth's troposphere 8-10. More studies using advanced genomic techniques such as shotgun metagenomic sequencing will be essential to formulating predictive models of bioaerosols and how the atmospheric microbiome is influenced by meteorological

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“…(iv) Potential phylogenetic and geographic sources of ice-nucleating bacteria. The 16S rRNA gene sequences from 45 of the 65 precipitation events were successfully amplified, sequenced, and analyzed (69). Of the OTUs that correlate significantly with INP concentrations (Table S6), many are related to bacterial taxa documented in soils, plant ecosystems, air, and precipitation (69,114,115).…”

Section: Discussionmentioning

confidence: 99%

“…The 16S rRNA gene sequences from 45 of the 65 precipitation events were successfully amplified, sequenced, and analyzed (69). Of the OTUs that correlate significantly with INP concentrations (Table S6), many are related to bacterial taxa documented in soils, plant ecosystems, air, and precipitation (69,114,115). Although there were no significant trends between INPs and the known ice-nucleating genera Pseudomonas or Pantoea, there are significant correlations between OTUs from Xanthomonadaceae (i.e., containing the IN species Xanthomonas campestris) and the total Ϫ5 to Ϫ11 , total Ϫ11 to Ϫ14 , and bio Ϫ5 to Ϫ10 factors.…”

Section: Discussionmentioning

confidence: 99%

“…The V4 region of the 16S rRNA gene was successfully PCR amplified using DNA extracted from 45 of the 65 precipitation events, and the amplicons were sequenced on a MiSeq platform (Illumina, Inc., San Diego, CA, USA). Contamination was assessed by attempting PCR amplification with the V4 primers on extracts from the procedural controls, as described by Aho et al (69). The sequences obtained were analyzed using the mothur software (70) and aligned to a SILVA bacterial 16S rRNA gene reference alignment (71).…”

Section: Methodsmentioning

confidence: 99%

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Biological Ice-Nucleating Particles Deposited Year-Round in Subtropical Precipitation

Joyce

Lavender

Farrar

et al. 2019

Appl Environ Microbiol

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Airborne bacteria that nucleate ice at relatively warm temperatures (>−10°C) can interact with cloud water droplets, affecting the formation of ice in clouds and the residency time of the cells in the atmosphere. We sampled 65 precipitation events in southeastern Louisiana over 2 years to examine the effect of season, meteorological conditions, storm type, and ecoregion source on the concentration and type of ice-nucleating particles (INPs) deposited. INPs sensitive to heat treatment were inferred to be biological in origin, and the highest concentrations of biological INPs (∼16,000 INPs liter−1 active at ≥–10°C) were observed in snow and sleet samples from wintertime nimbostratus clouds with cloud top temperatures as warm as –7°C. Statistical analysis revealed three temperature classes of biological INPs (INPs active from −5 to –10°C, −11 to –12°C, and −13 to –14°C) and one temperature class of INPs that were sensitive to lysozyme (i.e., bacterial INPs, active from −5 to –10°C). Significant correlations between the INP data and abundances of taxa in the Bacteroidetes, Firmicutes, and unclassified bacterial divisions implied that certain members of these phyla may possess the ice nucleation phenotype. The interrelation between the INP classes and fluorescent dissolved organic matter, major ion concentrations (Na+, Cl−, SO42−, and NO3−), and backward air mass trajectories indicated that the highest concentrations of INPs were sourced from high-latitude North American and Asian continental environments, whereas the lowest values were observed when air was sourced from marine ecoregions. The intra- and extracontinental regions identified as sources of biological INPs in precipitation deposited in the southeastern United States suggests that these bioaerosols can disperse and affect meteorological conditions thousands of kilometers from their terrestrial points of origin. IMPORTANCE The particles most effective at inducing the freezing of water in the atmosphere are microbiological in origin; however, information on the species harboring this phenotype, their environmental distribution, and ecological sources are very limited. Analysis of precipitation collected over 2 years in Louisiana showed that INPs active at the warmest temperatures were sourced from terrestrial ecosystems and displayed behaviors that implicated specific bacterial taxa as the source of the ice nucleation activity. The abundance of biological INPs was highest in precipitation from winter storms and implied that their in-cloud concentrations were sufficient to affect the formation of ice and precipitation in nimbostratus clouds.

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Spatiotemporal patterns of microbial composition and diversity in precipitation

Cited by 16 publications

References 121 publications

Scavenging of Sub-Micron to Micron-Sized Microbial Aerosols during Simulated Rainfall

Scavenging of Sub-Micron to Micron-Sized Microbial Aerosols during Simulated Rainfall

Sierra Nevada sweep: metagenomic measurements of bioaerosols vertically distributed across the troposphere

Biological Ice-Nucleating Particles Deposited Year-Round in Subtropical Precipitation

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