GlacialWater: A Dynamic Microbial Medium

Microbial communities and nutrient dynamics in glaciers and ice sheets continuously change as the hydrological conditions within and on the ice change. Glaciers and ice sheets can be considered bioreactors as microbiomes transform nutrients that enter these icy systems and alter the meltwater chemistry. Global warming is increasing meltwater discharge, affecting nutrient and cell export, and altering proglacial systems. In this review, we integrate the current understanding of glacial hydrology, microbial activity, and nutrient and carbon dynamics to highlight their interdependence and variability on daily and seasonal time scales, as well as their impact on proglacial environments

Xerotolerant bacteria : surviving through a dry spell

Water is vital for many biological processes and is essential for all living organisms. However, numerous macroorganisms and microorganisms have adapted to survive in environments in which water is scarce; such organisms are collectively termed xerotolerant. With increasing global desertification due to climate change and human-driven desertification processes, it is becoming ever more important to understand how xerotolerant organisms cope with a lack of water. In this Review, we discuss the environmental, physiological and molecular adaptations that enable xerotolerant bacteria to survive in environments in which water is scarce and highlight insights from modern 'omics' technologies. Understanding xerotolerance will inform and hopefully aid efforts to regulate and even reverse desertification.https://www.nature.com/nrmicrohj2018Genetic

In silico characterization of the global Geobacillus and Parageobacillus secretome

BACKGROUND : Geobacillus and Parageobacillus are two ecologically diverse thermophilic genera within the phylum Firmicutes. These taxa have long been of biotechnological interest due to their ability to secrete thermostable enzymes and other biomolecules that have direct applications in various industrial and clinical fields. Despite the commercial and industrial interest in these microorganisms, the full scope of the secreted protein, i.e. the secretome, of Geobacillus and Parageobacillus species remains largely unexplored, with most studies focusing on single enzymes. A genome-wide exploration of the global secretome can provide a platform for understanding the extracellular functional “protein cloud” and the roles that secreted proteins play in the survival and adaptation of these biotechnologically relevant organisms. RESULTS : In the present study, the global secretion profile of 64 Geobacillus and Parageobacillus strains, comprising 772 distinct proteins, was predicted using comparative genomic approaches. Thirty-one of these proteins are shared across all strains used in this study and function in cell-wall/membrane biogenesis as well as transport and metabolism of carbohydrates, amino acids and inorganic ions. An analysis of the clustering patterns of the secretomes of the 64 strains according to shared functional orthology revealed a correlation between the secreted profiles of different strains and their phylogeny, with Geobacillus and Parageobacillus species forming two distinct functional clades. CONCLUSIONS : The in silico characterization of the global secretome revealed a metabolically diverse set of secreted proteins, which include proteases, glycoside hydrolases, nutrient binding proteins and toxins.Additional file 1: Table S1. Similarity matrix. Table showing the percentage of orthology between the secretomes of the 64 genomes used in this study. This similarity matrix was used to generate the orthology dendogram in Fig. 6.Additional file 2: Table S2. Presence/absence matrix of the global secretome of Geobacillus and Parageobacillus. Table showing the presence or absence of the 772 protein sequences constituting the global secretome (annotated in the first row) across the 64 genomes used in this study (annotated in the first column). Presence/absence is indicated using a binary code of 1 and 0 to represent presence and absence, respectively.Additional file 3: Figure S1. Distribution of GH families across the 51 glycoside hydrolases present in the global secretome. Pie-chart showing the distribution of glycoside hydrolase families in the global secretome of Geobacillus and Parageobacillus. The four most abundant families represented in the dataset include beta-galactosidases (GH2), alpha-amylases (GH13), chitinases (GH18), and lytic transglycosylases (GH23). The following families were also found to be present in the global secretome: GH1– beta-glucosidases and beta-galactosidases; GH 3–beta-d-glucosidases, alpha-l-arabinofuranosidases; GH5–cellulases; GH10–endo-beta-1,3-xylanases; GH19–chitinases; GH25–chalaropsis-type lysozymes; GH27–alphagalactosidases and alpha-N-acetylgalactosaminidases; GH32–invertases; GH43–endo-alpha-l-arabinanases and beta-d-xylosidases; GH52–betaxylosidases; GH53–beta-1,4-galactanases; GH70–transglucosylases; GH73–beta-N-acetylglucosaminidases.Additional file 4: Figure S2. Xylanase activity assay of Geobacillus and Parageobacillus type strains on Oat Spelt Xylan. Bar-plot showing the xylan degrading activity of the supernatant of selected Geobacillus and Parageobacillus strains, as measured using the DNS protocol [91]. The concentration of reduced sugars was determined by measuring the average absorbance of each sample against a xylose standard. Strains were labelled as follow: T1–P. thermoglucosidasius DSM 2542T; T2–G. subterraneus DSM 15332T; T3–P. caldoxylosilyticus DSM 12041T; T4–G. thermodenitrificans DSM 465T; T5–G. stearothermophilus ATCC 12980T; T6–G. kaustophilus DSM 7263T; T7–P. thermoantarcticus M1T; T8 - P. toebii DSM 14590T.Additional file 5: Figure S3. Qualitative amylase activity plate assays. Description of data: 1% Starch agar plates showing the starch-degrading activity of the supernatant of the Geobacilus and Parageobacillus strains tested. The plates were stained with iodine tincture (2.5% w/v Iodine, 2.5% Potassium Iodide), and the areas of clearance represent starch degradation and corresponding amylase activity. The strains were labelled as described for Figure S2, and the positive control used in this assay (+) is α-amylase from Aspergillus oryzae, provided by Sigma-Aldrich® (Product Code: 9001-19-8).Additional file 6: Figure S4. PNPB Lipase activity assay of Geobacillus and Parageobacillus strains. Description of data: Bar-plot showing the degradation rates of PNPB by the supernatant of the eight Geobacillus and Parageobacillus strains tested. The labelling for the different strains is the same as described for Additional file 4: Figure S2.Additional file 7: Table S3. Blast results for proteins with homology to biotechnologically relevant enzymes. Description of data: Table showing the blast results for the most significant hits between protein sequences from the global secretome and enzymes from the Uniprot database that have been previously highlighted as being of biotechnological relevance. The scores and e-values, as well as the accession numbers were obtained using the Blast function against the UniprotDB.This study was funded through a University of Pretoria (UP) Postdoctoral Researcher fellowship.A University of Pretoria (UP) Postdoctoral Researcher fellowship.http://www.microbialcellfactories.comam2019BiochemistryGeneticsMicrobiology and Plant Patholog

In silico characterization of the global Geobacillus and Parageobacillus secretome

Additional file 1: Table S1. Similarity matrix. Table showing the percentage of orthology between the secretomes of the 64 genomes used in this study. This similarity matrix was used to generate the orthology dendogram in Fig. 6

Phylogenomic re-assessment of the thermophilic genus Geobacillus

Geobacillus is a genus of Gram-positive, aerobic, spore-forming obligate thermophiles. The descriptions and subsequent affiliations of the species in the genus have mostly been based on polyphasic taxonomy rules that include traditional sequence-based methods such as DNA–DNA hybridization and comparison of 16S rRNA gene sequences. Currently, there are fifteen validly described species within the genus. The availability of whole genome sequences has provided an opportunity to validate and/or re-assess these conventional estimates of genome relatedness. We have applied whole genome approaches to estimate the phylogenetic relatedness among the sixty-three Geobacillus strains for which genome sequences are currently publicly available, including the type strains of eleven validly described species. The phylogenomic metrics AAI (Average Amino acid Identity), ANI (Average Nucleotide Identity) and dDDH (digital DNA–DNA hybridization) indicated that the current genus Geobacillus is comprised of sixteen distinct genomospecies, including several potentially novel species. Furthermore, a phylogeny constructed on the basis of the core genes identified from the whole genome analyses indicated that the genus clusters into two monophyletic clades that clearly differ in terms of nucleotide base composition. The G + C content ranges for clade I and II were 48.8–53.1% and 42.1–44.4%, respectively. We therefore suggest that the Geobacillus species currently residing within clade II be considered as a new genusSupplementary Figure S1: AAI relationships among sixty-three strains of Geobacillus. The dendrogram was constructed using the distances matrices (derived from ANI and dDDH values) using the web server DendroUPGMA [14].Supplementary Table S1: Genome features of sixty-three Geobacillus strains included in this study. The original species and strain designations are indicated, as are the genome size, GenBank Assembly accession numbers or Integrate Microbial Genomics database project ID. The status of the original genome sequence (Complete or Draft), number of contigs for the original and final assembly are shown. The number of genes coded on the genome (as predicted with RAST) and G+C content (%) are indicated.Supplementary Table S2: ANI and dDDH relationships among sixty-three strains of Geobacillus species. The lower triangle shows the ANI values with the 96% threshold higlighted using bottom and left borders. The blue, white and red colour code (0-100%) was used to depict the contrast between the ANI values of the two major clades identified in this study. The upper triangle shows the dDDH values with 70% threshold demacated using upper and right borders. The red, yellow and green colour code (0-100%) was used to highlight the contrast between the dDDH values of the two major clades. The strains names were annotated with different colour fills to indicate species recognised in this study. The two major clades identified in this study are demarcated by a thick border line.Supplementary Table S3: AAI relationships among sixty-three strains of Geobacillus species. The green, yellow and red colour code (0-100%) was used to highlight the AAI among the Geobacillus species included in this study. The strains names were annotated with different colour fills to indicate species recognised in this study. The species grouping within the clades are highlighted using the different colour fills in the species names. The two major clades identified in this study are demarcated using a thick border line.The University of Pretoria (Habibu Aliyu—University of Pretoria Postdoctoral Fellowship funding), National Research Foundation (Pieter De Maayer—Research Career Advancement Fellowship, Grant # 91447) and the University of Pretoria Genomic Research Institute.http:// www.elsevier.de/syapm2017-12-30hb2016GeneticsMicrobiology and Plant Patholog

Microbial diversity in Antarctic Dry Valley soils across an altitudinal gradient

DATA AVAILABILITY STATEMENT : The datasets presented in this study can be found in online repositories. The names of the repository/repositories and accession number(s) can be found at: https://www.ebi.ac.uk/ena, PRJEB55870.INTRODUCTION : The Antarctic McMurdo Dry Valleys are geologically diverse, encompassing a wide variety of soil habitats. These environments are largely dominated by microorganisms, which drive the ecosystem services of the region. While altitude is a well-established driver of eukaryotic biodiversity in these Antarctic ice-free areas (and many non-Antarctic environments), little is known of the relationship between altitude and microbial community structure and functionality in continental Antarctica. METHODS : We analysed prokaryotic and lower eukaryotic diversity from soil samples across a 684 m altitudinal transect in the lower Taylor Valley, Antarctica and performed a phylogenic characterization of soil microbial communities using short-read sequencing of the 16S rRNA and ITS marker gene amplicons. RESULTS AND DISCUSSION : Phylogenetic analysis showed clear altitudinal trends in soil microbial composition and structure. Cyanobacteria were more prevalent in higher altitude samples, while the highly stress resistant Chloroflexota and Deinococcota were more prevalent in lower altitude samples. We also detected a shift from Basidiomycota to Chytridiomycota with increasing altitude. Several genera associated with trace gas chemotrophy, including Rubrobacter and Ornithinicoccus, were widely distributed across the entire transect, suggesting that trace-gas chemotrophy may be an important trophic strategy for microbial survival in oligotrophic environments. The ratio of trace-gas chemotrophs to photoautotrophs was significantly higher in lower altitude samples. Cooccurrence network analysis of prokaryotic communities showed some significant differences in connectivity within the communities from different altitudinal zones, with cyanobacterial and trace-gas chemotrophy-associated taxa being identified as potential keystone taxa for soil communities at higher altitudes. By contrast, the prokaryotic network at low altitudes was dominated by heterotrophic keystone taxa, thus suggesting a clear trophic distinction between soil prokaryotic communities at different altitudes. Based on these results, we conclude that altitude is an important driver of microbial ecology in Antarctic ice-free soil habitats.The National Research Foundation, the University of Pretoria, Antarctica New Zealand and the New Zealand Ministry of Business Innovation and Employment (MBIE).http://www.frontiersin.org/Microbiologyam2024BiochemistryGeneticsMicrobiology and Plant PathologySDG-15:Life on lan

The use of different 16S rRNA gene variable regions in biogeographical studies

DATA AVAILABILITY STATEMENT : All Illumina sequences generated and analyzed in this study were deposited into the European Nucleotide Archive (accession number PRJEB55051).SUPPORTING INFORMATION 1 : FIGURE S1. Samples located in four inland areas of the Prince Charles Mountains (ME1 from Mount Rubin, ME2 and ME3 from Mawson Escarpment, MM1 and MM2 from Mount Menzies, LT1 and LT2 from Lake Terrasovoje), in the Reinbolt Hills (RH1), and in coastal sites in proximity of the Prince Charles Mountains (C1 and C2; see Table S1). Map was produced using MODIS mosaic (125 m) imagery distributed by Quantarctica (https://cmr.earthdata.nasa.gov/; https://www.npolar.no/quantarctica/). FIGURE S2. Pearson's pairwise correlations between Bray–Curtis dissimilarity matrices calculated on relative abundance taxonomic dataset (genus level; A), and between Jaccard dissimilarity matrices calculated on presence/absence taxonomic dataset (genus level; B). Correlations were calculated for all the variable region datasets (V1–V3, V3–V4, V4, V4–V5 and V8–V9), and the mixed datasets (Mix 1, Mix 2 and Mix 3) constituted by randomly picked samples from V1–V3, V3–V4, V4, V4–V5 and V8–V9 (Table S4). Pearson's correlation coefficients (r) are reported only in case of significant correlation (p < 0.05).SUPPORTING INFORMATION 2 : TABLE S1. Sample specifics. TABLE S2. Geochemical data. TABLE S3. Relative abundance (%) of the taxonomic domains Bacteria and Archaea in sample (i.e., ME1, ME2, ME3, MM1, MM2, LT1, LT2, RH1, C1 and C2) for each variable region dataset (i.e., V1–V3, V3–V4, V4, V4–V5 and V8–V9). TABLE S4. Composition of mixed communities. TABLE S5. Number of reads at each step of the 16S rRNA gene processing pipeline. *counts reported as read pairs. TABLE S6. Number and percentage of unknown amplicon sequence variants (ASVs) at genus level for each phylum. TABLE S7. Relative abundance associated to unknown amplicon sequence variants at genus-level for each phylum. TABLE S8. Pearson's correlations from pairwise comparisons of variable region datasets performed on number of genera (A), dominant genera (i.e., genera represented by a relative abundance higher than 1% in at least one sample) (B), rare genera (i.e., genera represented by a relative abundance lower than 0.1% in all samples (C), Shannon index (D) and unique genera (E).16S rRNA gene amplicon sequencing is routinely used in environmental surveys to identify microbial diversity and composition of the samples of interest. The dominant sequencing technology of the past decade (Illumina) is based on the sequencing of 16S rRNA hypervariable regions. Online sequence data repositories, which represent an invaluable resource for investigating microbial distributional patterns across spatial, environmental or temporal scales, contain amplicon datasets from diverse 16S rRNA gene variable regions. However, the utility of these sequence datasets is potentially reduced by the use of different 16S rRNA gene amplified regions. By comparing 10 Antarctic soil samples sequenced for five different 16S rRNA amplicons, we explore whether sequence data derived from diverse 16S rRNA variable regions can be validly used as a resource for biogeographical studies. Patterns of shared and unique taxa differed among samples as a result of variable taxonomic resolutions of the assessed 16S rRNA variable regions. However, our analyses also suggest that the use of multi-primer datasets for biogeographical studies of the domain Bacteria is a valid approach to explore bacterial biogeographical patterns due to the preservation of bacterial taxonomic and diversity patterns across different variable region datasets. We deem composite datasets useful for biogeographical studies.Australian Antarctic Division, Australian Research Council and NRF SANAP.http://wileyonlinelibrary.com/journal/emi4hj2023BiochemistryGeneticsMicrobiology and Plant Patholog

Microdiverse bacterial clades prevail across Antarctic wetlands

DATA AVAILABILITY STATEMENT : The sequence data are publicly available at NCBI BioProject database (ID PRJNA719989, 64 sequence data links, https://www.ncbi.nlm.nih.gov/bioproject/PRJNA719989). R code for nearest taxon distance (NTD) and nucleotide similarity of β-nearest ASV indexes, and the modified version of feature-level βNTI index are available at GitHub (https://github.com/mvquiroga/NullModels).Antarctica's extreme environmental conditions impose selection pressures on microbial communities. Indeed, a previous study revealed that bacterial assemblages at the Cierva Point Wetland Complex (CPWC) are shaped by strong homogeneous selection. Yet which bacterial phylogenetic clades are shaped by selection processes and their ecological strategies to thrive in such extreme conditions remain unknown. Here, we applied the phyloscore and feature-level βNTI indexes coupled with phylofactorization to successfully detect bacterial monophyletic clades subjected to homogeneous (HoS) and heterogenous (HeS) selection. Remarkably, only the HoS clades showed high relative abundance across all samples and signs of putative microdiversity. The majority of the amplicon sequence variants (ASVs) within each HoS clade clustered into a unique 97% sequence similarity operational taxonomic unit (OTU) and inhabited a specific environment (lotic, lentic or terrestrial). Our findings suggest the existence of microdiversification leading to sub-taxa niche differentiation, with putative distinct ecotypes (consisting of groups of ASVs) adapted to a specific environment. We hypothesize that HoS clades thriving in the CPWC have phylogenetically conserved traits that accelerate their rate of evolution, enabling them to adapt to strong spatio-temporally variable selection pressures. Variable selection appears to operate within clades to cause very rapid microdiversification without losing key traits that lead to high abundance. Variable and homogeneous selection, therefore, operate simultaneously but on different aspects of organismal ecology. The result is an overall signal of homogeneous selection due to rapid within-clade microdiversification caused by variable selection. It is unknown whether other systems experience this dynamic, and we encourage future work evaluating the transferability of our results.ANPCyT - Argentina; European Union; Instituto Antártico Argentino - Dirección Nacional del Antártico; Junta de Castilla y León; NRF - South Africa; U.S. Department of Energy-BER program.https://wileyonlinelibrary.com/journal/mechj2024BiochemistryGeneticsMicrobiology and Plant PathologySDG-15:Life on lan

The soil microbiomics of intact, degraded and partially-restored semi-arid succulent thicket (Albany Subtropical Thicket)

This study examines the soil bacterial diversity in the Portulacaria afra-dominated succulent thicket vegetation of the Albany Subtropical Thicket biome; this biome is endemic to South Africa. The aim of the study was to compare the soil microbiomes between intact and degraded zones in the succulent thicket and identify environmental factors which could explain the community compositions. Bacterial diversity, using 16S amplicon sequencing, and soil physicochemistry were compared across three zones: intact (undisturbed and vegetated), degraded (near complete removal of vegetation due to browsing) and restored (a previously degraded area which was replanted approximately 11 years before sampling). Amplicon Sequence Variant (ASV) richness was similar across the three zones, however, the bacterial community composition and soil physicochemistry differed across the intact and degraded zones. We identified, via correlation, the potential drivers of microbial community composition as soil density, pH and the ratio of Ca to Mg. The restored zone was intermediate between the intact and degraded zones. The differences in the microbial communities appeared to be driven by the presence of plants, with plant-associated taxa more common in the intact zone. The dominant taxa in the degraded zone were cosmopolitan organisms, that have been reported globally in a wide variety of habitats. This study provides baseline information on the changes of the soil bacterial community of a spatially restricted and threatened biome. It also provides a starting point for further studies on community composition and function concerning the restoration of degraded succulent thicket ecosystems.The research presented here was part of a BSc (Hons) thesis (MS).Supplement 1 : Evidence of long-term degradation of the Sundays Arid Thicket (Albany Subtropical Thicket biome) on the slopes of the study site. Aerial images show that this degraded state has been in effect for at least 60 years: (A) satellite image from 2020 (Map data: ©2021 Google Earth, Maxar Technologies), (B) aerial photo taken in 1961 by the South African Chief Directorate of National Geo-spatial information (Reproduced under Government’s Printer Authorisation [Authorisation No. 11851 dated 08 September 2021]). Ground-based repeat photography demonstrates the loss of the majority of remaining trees since 1986: photos taken in (C) 2016 and (D) 1986 (Photo credit: MT Hoffman). Note that, in (C) and (D), the area in this study is not in the area photographed (it is off to the right). DOI: 10.7717/peerj.12176/supp-1Supplement 2 : Trends lines of soil relative humidity and temperature. Trend lines of soil relative humidity (blue) and temperature (red) over (A–C) the full duration of measurements or (D–F) the daily average. The pale points show the individual measurements and the grey border around the trend lines depicts the 95% confidence interval. DOI: 10.7717/peerj.12176/supp-2Supplement 3 : Comparison of soil temperature between the different vegetation types. (A) Boxplots of data points from three iButtons per zone. Significant differences were determined using the Wilcox test. (B) Mean daily maximum (solid lines) and minimum (dashed lines) temperature over the three zones. (C) Daily difference between the mean temperatures shown in (B). DOI: 10.7717/peerj.12176/supp-3Supplement 4 : Comparison of soil relative humidity between the different vegetation types. Boxplots of data points from three iButtons per zone (A). Significant differences were determined using the Wilcox test. Mean daily maximum (solid lines) and minimum (dashed lines) relative humidity over the three zones (B). Daily difference between the mean relative humidities shown in B (C). DOI: 10.7717/peerj.12176/supp-4Alpha diversity of samples as the number of (A) observed ASVs or (B) Shannon index. Significance was determined using the Wilcox test. DOI: 10.7717/peerj.12176/supp-5Supplement 6 : Heatmap of samples using weighted Jaccard distance. Overall the samples show low levels of similarity to one another. DOI: 10.7717/peerj.12176/supp-6Supplement 7 : Genus-level differences between zones. Relative abundance of genus-level ASVs that account for ≥1% of the reads in the different zones. Significance was determined using the Wilcox test. DOI: 10.7717/peerj.12176/supp-7Supplement 8 : Network taxa with significantly different abundances in intact vs degraded zones. Genus-level ASVs used in the network construction are displayed with the name of the genus, if available, and show the relative abundance in both the intact and degraded zones. Each genus is coloured according to the clustering in the degraded network (Fig. 5). Significance was determined using the Wilcox test and only the genera which had significant differences between their abundance in the different zones are shown. DOI: 10.7717/peerj.12176/supp-8Supplement 9 : Succulent thicket metadata. DOI: 10.7717/peerj.12176/supp-9Supplement 10 : Summary statistics of iButton measurements in the succulent thicket. DOI: 10.7717/peerj.12176/supp-10Supplement 11 : Core bacterial community of the succulent thicket. DOI: 10.7717/peerj.12176/supp-11Supplement 12 : Core bacterial community of the intact succulent thicket. DOI: 10.7717/peerj.12176/supp-12Supplement 13 : Core bacterial community of the degraded succulent thicket. DOI: 10.7717/peerj.12176/supp-13Supplement 14 : Core bacterial community of the restored succulent thicket. DOI: 10.7717/peerj.12176/supp-14Supplement 15 : Unique core bacterial community members of different vegetation conditions in the succulent thicket. DOI: 10.7717/peerj.12176/supp-15Supplement 16 : The number of unique to near-unique ASVs detected in the intact and degraded zone according to the prevalence threshold within and out of the specific zone. Prevalence thresholds are given both as a percentage (%) and as the equivalent number of sites (n) in the intact and degraded zones. The thresholds and resultant ASV counts analysed in this study are shown in bold DOI: 10.7717/peerj.12176/supp-16The University of Pretoria, the National Research Foundation of South Africa and the Department of Environment, Forestry and Fisheries: Natural Resource Management Programme.https://peerj.comam2022BiochemistryGeneticsMicrobiology and Plant Patholog

Gone with the wind : microbial communities associated with dust from emissive farmlands

Dust is a major vehicle for the dispersal of microorganisms across the globe. While much attention has been focused on microbial dispersal in dust plumes from major natural dust sources, very little is known about the fractionation processes that select for the “dust microbiome.” The recent identification of highly emissive, agricultural land dust sources in South Africa has provided the opportunity to study the displacement of microbial communities through dust generation and transport. In this study, we aimed to document the microbial communities that are carried in the dust from one of South Africa’s most emissive locations, and to investigate the selective factors that control the partitioning of microbial communities from soil to dust. For this purpose, dust samples were generated at different emission sources using a Portable In-Situ Wind Erosion Lab (PI-SWERL), and the taxonomic composition of the resulting microbiomes was compared with the source soils. Dust emission processes resulted in the clear fractionation of the soil bacterial community, where dust samples were significantly enriched in spore-forming taxa. Conversely, little fractionation was observed in the soil fungal communities, such that the dust fungal fingerprint could be used to identify the source soil. Dust microbiomes were also found to vary according to the emission source, suggesting that land use significantly affected the structure and fractionation of microbial communities transported in dust plumes. In addition, several potential biological allergens of fungal origin were detected in the dust microbiomes, highlighting the potential detrimental effects of dust plumes emitted in South Africa. This study represents the first description of the fractionation of microbial taxa occurring at the source of dust plumes and provides a direct link between land use and its impact on the dust microbiome.The South African National Research Foundation under the Swiss-South Africa Joint Research Program.http://link.springer.com/journal/2482022-02-07hj2021BiochemistryGeneticsMicrobiology and Plant Patholog