Functional redundancy buffers the effect of poly-extreme environmental conditions on southern African dryland soil microbial communities.

Drylands' poly-extreme conditions limit edaphic microbial diversity and functionality. Furthermore, climate change exacerbates soil desiccation and salinity in most drylands. To better understand the potential effects of these changes on dryland microbial communities, we evaluated their taxonomic and functional diversities in two Southern African dryland soils with contrasting aridity and salinity.

Microbial diversity in the arid and semi-arid soils of Botswana.

To date, little research has been conducted on the landscape-scale distribution of soil microbial communities and the factors driving their community structures in the drylands of Africa. We investigated the influence of landscape-scale variables on microbial community structure and diversity across different ecological zones in Botswana. We used amplicon sequencing of bacterial 16S rRNA gene and fungal internal transcribed spacers (ITS) and a suite of environmental parameters to determine drivers of microbial community structure.

Kinetics and pathways of sub-lithic microbial community (hypolithon) development.

Type I hypolithons are microbial communities dominated by Cyanobacteria. They adhere to the underside of semi-translucent rocks in desert pavements, providing them with a refuge from the harsh abiotic stresses found on the desert soil surface. Despite their crucial role in soil nutrient cycling, our understanding of their growth rates and community development pathways remains limited.

Brucella pituitosa strain BU72, a new hydrocarbonoclastic bacterium through exopolysaccharide-based surfactant production.

Hydrocarbon and heavy metal pollution are amongst the most severe and prevalent environmental problems due to their toxicity and persistence. Bioremediation using microorganisms is considered one of the most effective ways to treat polluted sites. In the present study, we unveil the bioremediation potential of Brucella pituitosa strain BU72.

Changes in nutrient availability substantially alter bacteria and extracellular enzymatic activities in Antarctic soils.

In polar regions, global warming has accelerated the melting of glacial and buried ice, resulting in meltwater run-off and the mobilization of surface nutrients. Yet, the short-term effects of altered nutrient regimes on the diversity and function of soil microbiota in polyextreme environments such as Antarctica, remains poorly understood. We studied these effects by constructing soil microcosms simulating augmented carbon, nitrogen, and moisture.

Temporal dynamics of microbial transcription in wetted hyperarid desert soils.

Rainfall is rare in hyperarid deserts but, when it occurs, it triggers large biological responses essential for the long-term maintenance of the ecosystem. In drylands, microbes play major roles in nutrient cycling, but their responses to short-lived opportunity windows are poorly understood. Due to its ephemeral nature, mRNA is ideally suited to study microbiome dynamics upon abrupt changes in the environment.

Documenting the diversity of the Namibian Ju|'hoansi intestinal microbiome.

We investigate the bacterial and fungal composition and functionality of the Ju|'hoansi intestinal microbiome (IM). The Juǀ'hoansi are a hunter-gatherer community residing in northeastern Namibia. They formerly subsisted by hunting and gathering but have been increasingly exposed to industrial dietary sources, medicines, and lifestyle features.

Biogeographic survey of soil bacterial communities across Antarctica.

Background: Antarctica and its unique biodiversity are increasingly at risk from the effects of global climate change and other human influences. A significant recent element underpinning strategies for Antarctic conservation has been the development of a system of Antarctic Conservation Biogeographic Regions (ACBRs). The datasets supporting this classification are, however, dominated by eukaryotic taxa, with contributions from the bacterial domain restricted to Actinomycetota and Cyanobacteriota.

With a pinch of salt: metagenomic insights into Namib Desert salt pan microbial mats and halites reveal functionally adapted and competitive communities.

The hyperarid Namib Desert is one of the oldest deserts on Earth. It contains multiple clusters of playas which are saline-rich springs surrounded by halite evaporites. Playas are of great ecological importance, and their indigenous (poly)extremophilic microorganisms are potentially involved in the precipitation of minerals such as carbonates and sulfates and have been of great biotechnological importance.

Characterization of the soil resistome and mobilome in Namib Desert soils.

The study of the soil resistome is important in understanding the evolution of antibiotic resistance and its dissemination between the clinic and the environment. However, very little is known about the soil resistome, especially of those from deserts. Here, we characterize the bacterial communities, using targeted sequencing of the 16S rRNA genes, and both the resistome and the mobilome in Namib Desert soils, using shotgun metagenomics.

Clearing the air: unraveling past and guiding future research in atmospheric chemosynthesis.

Atmospheric chemosynthesis is a recently proposed form of chemoautotrophic microbial primary production. The proposed process relies on the oxidation of trace concentrations of hydrogen (≤530 ppbv), carbon monoxide (≤90 ppbv), and methane (≤1,870 ppbv) gases using high-affinity enzymes. Atmospheric hydrogen and carbon monoxide oxidation have been primarily linked to microbial growth in desert surface soils scarce in liquid water and organic nutrients, and low in photosynthetic communities.

The core bacteriobiome of Côte d'Ivoire soils across three vegetation zones.

The growing understanding that soil bacteria play a critical role in ecosystem servicing has led to a number of large-scale biogeographical surveys of soil microbial diversity. However, most of such studies have focused on northern hemisphere regions and little is known of either the detailed structure or function of soil microbiomes of sub-Saharan African countries. In this paper, we report the use of high-throughput amplicon sequencing analyses to investigate the biogeography of soil bacteria in soils of Côte d'Ivoire.

Microbial diversity in Antarctic Dry Valley soils across an altitudinal gradient.

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.

Glacial Water: 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.

The soil microbiomes of forest ecosystems in Kenya: their diversity and environmental drivers.

Soil microbiomes in forest ecosystems act as both nutrient sources and sinks through a range of processes including organic matter decomposition, nutrient cycling, and humic compound incorporation into the soil. Most forest soil microbial diversity studies have been performed in the northern hemisphere, and very little has been done in forests within African continent. This study examined the composition, diversity and distribution of prokaryotes in Kenyan forests top soils using amplicon sequencing of V4-V5 hypervariable region of the 16S rRNA gene.

Rickettsia felis DNA recovered from a child who lived in southern Africa 2000 years ago.

The Stone Age record of South Africa provides some of the earliest evidence for the biological and cultural origins of Homo sapiens. While there is extensive genomic evidence for the selection of polymorphisms in response to pathogen-pressure in sub-Saharan Africa, e.g.

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

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.

Threat management priorities for conserving Antarctic biodiversity.

Antarctic terrestrial biodiversity faces multiple threats, from invasive species to climate change. Yet no large-scale assessments of threat management strategies exist. Applying a structured participatory approach, we demonstrate that existing conservation efforts are insufficient in a changing world, estimating that 65% (at best 37%, at worst 97%) of native terrestrial taxa and land-associated seabirds are likely to decline by 2100 under current trajectories.

Engineering enhanced thermostability into the nitrile hydratase.

Nitrile hydratases (NHases) are important biocatalysts for the enzymatic conversion of nitriles to industrially-important amides such as acrylamide and nicotinamide. Although thermostability in this enzyme class is generally low, there is not sufficient understanding of its basis for rational enzyme design. The gene expressing the Co-type NHase from the moderate thermophile, RAPc8 (NRRL B-59396), was subjected to random mutagenesis.

Atmospheric chemosynthesis is phylogenetically and geographically widespread and contributes significantly to carbon fixation throughout cold deserts.

Cold desert soil microbiomes thrive despite severe moisture and nutrient limitations. In Eastern Antarctic soils, bacterial primary production is supported by trace gas oxidation and the light-independent RuBisCO form IE. This study aims to determine if atmospheric chemosynthesis is widespread within Antarctic, Arctic and Tibetan cold deserts, to identify the breadth of trace gas chemosynthetic taxa and to further characterize the genetic determinants of this process.

The plant rhizosheath-root niche is an edaphic "mini-oasis" in hyperarid deserts with enhanced microbial competition.

Plants have evolved unique morphological and developmental adaptations to cope with the abiotic stresses imposed by (hyper)arid environments. Such adaptations include the formation of rhizosheath-root system in which mutualistic plant-soil microbiome associations are established: the plant provides a nutrient-rich and shielded environment to microorganisms, which in return improve plant-fitness through plant growth promoting services. We hypothesized that the rhizosheath-root systems represent refuge niches and resource islands for the desert edaphic microbial communities.

Microbial Biogeochemical Cycling of Nitrogen in Arid Ecosystems.

Arid ecosystems cover ∼40% of the Earth's terrestrial surface and store a high proportion of the global nitrogen (N) pool. They are low-productivity, low-biomass, and polyextreme ecosystems, i.e.

Out of Thin Air? Astrobiology and Atmospheric Chemotrophy.

The emerging understanding of microbial trace gas chemotrophy as a metabolic strategy to support energy and carbon acquisition for microbial survival and growth has significant implications in the search for past, and even extant, life beyond Earth. The use of trace gases, including hydrogen and carbon monoxide as substrates for microbial oxidation, potentially offers a viable strategy with which to support life on planetary bodies that possess a suitable atmospheric composition, such as Mars and Titan. Here, we discuss the current state of knowledge of this process and explore its potential in the field of astrobiological exploration.