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. Emperor penguins are identified as the most vulnerable taxon, followed by other seabirds and dry soil nematodes. We find that implementing 10 key threat management strategies in parallel, at an estimated present-day equivalent annual cost of US$23 million, could benefit up to 84% of Antarctic taxa. Climate change is identified as the most pervasive threat to Antarctic biodiversity and influencing global policy to effectively limit climate change is the most beneficial conservation strategy. However, minimising impacts of human activities and improved planning and management of new infrastructure projects are cost-effective and will help to minimise regional threats. Simultaneous global and regional efforts are critical to secure Antarctic biodiversity for future generations.

Microdiverse bacterial clades prevail across Antarctic wetlands.

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 ßNTI 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.

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. Besides its ability to grow on multiple hydrocarbons as the sole carbon source and highly tolerant to several heavy metals, BU72 produces different exopolysaccharide-based surfactants (EBS) when grown with glucose or with crude oil as sole carbon source. These EBS demonstrated particular and specific functional groups as determined by Fourier transform infrared (FTIR) spectral analysis that showed a strong absorption peak at 3250 cm-1 generated by the -OH group for both EBS. The FTIR spectra of the produced EBS revealed major differences in functional groups and protein content. To better understand the EBS production coupled with the degradation of hydrocarbons and heavy metal resistance, the genome of strain BU72 was sequenced. Annotation of the genome revealed multiple genes putatively involved in EBS production pathways coupled with resistance to heavy metals genes such as arsenic tolerance and cobalt-zinc-cadmium resistance. The genome sequence analysis showed the potential of BU72 to synthesise secondary metabolites and the presence of genes involved in plant growth promotion. Here, we describe the physiological, metabolic, and genomic characteristics of Brucella pituitosa strain BU72, indicating its potential as a bioremediation agent.

Multiple energy sources and metabolic strategies sustain microbial diversity in Antarctic desert soils.

Numerous diverse microorganisms reside in the cold desert soils of continental Antarctica, though we lack a holistic understanding of the metabolic processes that sustain them. Here, we profile the composition, capabilities, and activities of the microbial communities in 16 physicochemically diverse mountainous and glacial soils. We assembled 451 metagenome-assembled genomes from 18 microbial phyla and inferred through Bayesian divergence analysis that the dominant lineages present are likely native to Antarctica. In support of earlier findings, metagenomic analysis revealed that the most abundant and prevalent microorganisms are metabolically versatile aerobes that use atmospheric hydrogen to support aerobic respiration and sometimes carbon fixation. Surprisingly, however, hydrogen oxidation in this region was catalyzed primarily by a phylogenetically and structurally distinct enzyme, the group 1l [NiFe]-hydrogenase, encoded by nine bacterial phyla. Through gas chromatography, we provide evidence that both Antarctic soil communities and an axenic Bacteroidota isolate (Hymenobacter roseosalivarius) oxidize atmospheric hydrogen using this enzyme. Based on ex situ rates at environmentally representative temperatures, hydrogen oxidation is theoretically sufficient for soil communities to meet energy requirements and, through metabolic water production, sustain hydration. Diverse carbon monoxide oxidizers and abundant methanotrophs were also active in the soils. We also recovered genomes of microorganisms capable of oxidizing edaphic inorganic nitrogen, sulfur, and iron compounds and harvesting solar energy via microbial rhodopsins and conventional photosystems. Obligately symbiotic bacteria, including Patescibacteria, Chlamydiae, and predatory Bdellovibrionota, were also present. We conclude that microbial diversity in Antarctic soils reflects the coexistence of metabolically flexible mixotrophs with metabolically constrained specialists.

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

IMPORTANCE: 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. While there has been a considerable amount of microbial ecology research performed on various Namib Desert edaphic microbiomes, little is known about the microbial communities inhabiting its multiple playas. In this work, we provide a comprehensive taxonomic and functional potential characterization of the microbial, including viral, communities of sediment mats and halites from two distant salt pans of the Namib Desert, contributing toward a better understanding of the ecology of this biome.

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. We detected a variety of antibiotic resistance genes (ARGs) that conferred resistance to antibiotics such as elfamycin, rifampicin, and fluoroquinolones, metal/biocide resistance genes (MRGs/BRGs) conferring resistance to metals such as arsenic and copper, and mobile genetic elements (MGEs) such as the ColE1-like plasmid. The presence of metal/biocide resistance genes in close proximity to ARGs indicated a potential for co-selection of resistance to antibiotics and metals/biocides. The co-existence of MGEs and horizontally acquired ARGs most likely contributed to a decoupling between bacterial community composition and ARG profiles. Overall, this study indicates that soil bacterial communities in Namib Desert soils host a diversity of resistance elements and that horizontal gene transfer, rather than host phylogeny, plays an essential role in their dynamics.

Genetic diversity of soil invertebrates corroborates timing estimates for past collapses of the West Antarctic Ice Sheet.

During austral summer field seasons between 1999 and 2018, we sampled at 91 locations throughout southern Victoria Land and along the Transantarctic Mountains for six species of endemic microarthropods (Collembola), covering a latitudinal range from 76.0°S to 87.3°S. We assembled individual mitochondrial cytochrome c oxidase subunit 1 (COI) sequences (n = 866) and found high levels of sequence divergence at both small (<10 km) and large (>600 km) spatial scales for four of the six Collembola species. We applied molecular clock estimates and assessed genetic divergences relative to the timing of past glacial cycles, including collapses of the West Antarctic Ice Sheet (WAIS). We found that genetically distinct lineages within three species have likely been isolated for at least 5.54 My to 3.52 My, while the other three species diverged more recently (<2 My). We suggest that Collembola had greater dispersal opportunities under past warmer climates, via flotation along coastal margins. Similarly increased opportunities for dispersal may occur under contemporary climate warming scenarios, which could influence the genetic structure of extant populations. As Collembola are a living record of past landscape evolution within Antarctica, these findings provide biological evidence to support geological and glaciological estimates of historical WAIS dynamics over the last ca 5 My.

The ecological assembly of bacterial communities in Antarctic wetlands varies across levels of phylogenetic resolution.

As functional traits are conserved at different phylogenetic depths, the ability to detect community assembly processes can be conditional on the phylogenetic resolution; yet most previous work quantifying their influence has focused on a single level of phylogenetic resolution. Here, we have studied the ecological assembly of bacterial communities from an Antarctic wetland complex, applying null models across different levels of phylogenetic resolution (i.e. clustering ASVs into OTUs with decreasing sequence identity thresholds). We found that the relative influence of the community assembly processes varies with phylogenetic resolution. More specifically, selection processes seem to impose stronger influence at finer (100% sequence similarity ASV) than at coarser (99%-97% sequence similarity OTUs) resolution. We identified environmental features related with the ecological processes and propose a conceptual model for the bacterial community assembly in this Antarctic ecosystem. Briefly, eco-evolutionary processes appear to be leading to different but very closely related ASVs in lotic, lentic and terrestrial environments. In all, this study shows that assessing community assembly processes at different phylogenetic resolutions is key to improve our understanding of microbial ecology. More importantly, a failure to detect selection processes at coarser phylogenetic resolution does not imply the absence of such processes at finer resolutions.

Differences in Precipitation Regime Shape Microbial Community Composition and Functional Potential in Namib Desert Soils.

Precipitation is one of the major constraints influencing the diversity, structure, and activity of soil microbial communities in desert ecosystems. However, the effect of changes in precipitation on soil microbial communities in arid soil microbiomes remains unresolved. In this study, using 16S rRNA gene high-throughput sequencing and shotgun metagenome sequencing, we explored changes in taxonomic composition and functional potential across two zones in the Namib Desert with contrasting precipitation regime. We found that precipitation regime had no effect on taxonomic and functional alpha-diversity, but that microbial community composition and functional potential (beta-diversity) changed with increased precipitation. For instance, Acidobacteriota and 'resistance to antibiotics and toxic compounds' related genes were relatively more abundant in the high-rainfall zone. These changes were largely due to a small set of microbial taxa, some of which were present in low abundance (i.e. members of the rare biosphere). Overall, these results indicate that key climatic factors (i.e. precipitation) shape the taxonomic and functional attributes of the arid soil microbiome. This research provides insight into how changes in precipitation patterns associated with global climate change may impact microbial community structure and function in desert soils.

Novel lichen-dominated hypolithic communities in the Namib Desert.

The ventral surfaces of translucent rocks from hot desert pavements often harbor hypolithic microbial communities, which are mostly dominated by cyanobacteria. The Namib Desert fog belt supports extensive hypolithic colonization of quartz rocks, which are also colonized by lichens on their dorsal surfaces. Here, we aim to evaluate whether lichens colonize the ventral surface of the rocks (i.e., show hypolithic lifestyle) and compare the bacterial composition of these coastal hypolithic communities with those found inland. Fungal DNA barcoding and fungal and bacterial Illumina metabarcoding were combined with electron microscopy to characterize the composition and spatial structure of hypolithic communities from two (coastal and inland) areas in the Namib Desert. We report, for the first time, the structure and composition of lichen-dominated hypolithic communities found in the coastal zone of the Namib Desert with extensive epilithic lichen cover. Lichen modified areoles with inverted morphology of the genus Stellarangia (three lineages) and Buellia (two lineages) were the main components of these hypolithic communities. Some of these lineages were also found in epilithic habitats. These lichen-dominated hypolithic communities differed in structural organization and bacterial community composition from those found in inland areas. The hypolithic lichen colonization characterized here seems not to be an extension of epilithic or biological soil crust lichen growths but the result of specific sublithic microenvironmental conditions. Moisture derived from fog and dew could be the main driver of this unique colonization.

Sub-lithic photosynthesis in hot desert habitats.

In hyper-arid soil environments, photosynthetic microorganisms are largely restricted to hypolithic (sub-lithic) habitats: i.e., on the ventral surfaces of translucent pebbles in desert pavements. Here, we combined fluorometric, spectroscopic, biochemical and metagenomic approaches to investigate in situ the light transmission properties of quartz stones in the Namib Desert, and assess the photosynthetic activity of the underlying hypolithic cyanobacterial biofilms. Quartz pebbles greatly reduced the total photon flux to the ventral surface biofilms and filtered out primarily the short wavelength portion of the solar spectrum. Chlorophylls d and f were not detected in biofilm pigment extracts; however, hypolithic cyanobacterial communities showed some evidence of adaptation to sub-lithic conditions, including the prevalence of genes encoding Helical Carotenoid Proteins, which are associated with desiccation stress. Under water-saturated conditions, hypolithic communities showed no evidence of light stress, even when the quartz stones were exposed to full midday sunlight. This initial study creates a foundation for future in-situ and laboratory exploration of various adaptation mechanisms employed by photosynthetic organisms forming hypolithic microbial communities.

Microbial anhydrobiosis.

The loss of cellular water (desiccation) and the resulting low cytosolic water activity are major stress factors for life. Numerous prokaryotic and eukaryotic taxa have evolved molecular and physiological adaptions to periods of low water availability or water-limited environments that occur across the terrestrial Earth. The changes within cells during the processes of desiccation and rehydration, from the activation (and inactivation) of biosynthetic pathways to the accumulation of compatible solutes, have been studied in considerable detail. However, relatively little is known on the metabolic status of organisms in the desiccated state; that is, in the sometimes extended periods between the drying and rewetting phases. During these periods, which can extend beyond decades and which we term 'anhydrobiosis', organismal survival could be dependent on a continued supply of energy to maintain the basal metabolic processes necessary for critical functions such as macromolecular repair. Here, we review the state of knowledge relating to the function of microorganisms during the anhydrobiotic state, highlighting substantial gaps in our understanding of qualitative and quantitative aspects of molecular and biochemical processes in desiccated cells.

Pollution shapes the microbial communities in river water and sediments from the Olifants River catchment, South Africa.

Human activities such as agriculture and mining are leading causes of water pollution worldwide. Individual contaminants are known to negatively affect microbial communities. However, the effect of multifaceted pollution on these communities is less well understood. We investigated, using next-generation sequencing of the 16S rRNA genes, the effects of multisource (i.e., fertilizer industry and mining) chronic pollution on bacterial and archaeal communities in water and sediments from the Olifants River catchment, South Africa. Water samples showed less microbial species diversity than sediments and both habitats displayed different microbial communities. Within each of these habitats, pollution had no effect on alpha diversity but shaped the microbial composition and taxonomy-based predicted functions. Certain prokaryotic taxa and functional groups were indicative of different degrees of pollution. Heterotrophic taxa (e.g., Flavobacterium sp.) and sulphur-oxidizing bacteria (i.e., Thiobacillus sp.) were indicators of pollution in water and sediments, respectively. Ultimately, this information could be used to develop microbial indicators of water quality degradation.

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.

Distinct assembly mechanisms underlie similar biogeographical patterns of rare and abundant bacteria in Tibetan Plateau grassland soils.

Rare biosphere represents the majority of Earth's biodiversity and performs vital ecological functions, yet little is known about its biogeographical patterns and community assembly processes in terrestrial ecosystems. Herein, we investigated the community composition and phylogeny of rare (relative abundance <0.1%) and abundant (>1%) bacteria in dryland grassland soils on the Tibetan Plateau. Results revealed similar biogeographical patterns of rare and abundant bacteria at both compositional and phylogenetic levels, but rare subcommunity was more heavily influenced by stochasticity (72%) than the abundant (57%). The compositional variation of rare bacteria was less explained by environmental factors (41%) than that of the abundant (80%), while the phylogeny of rare bacteria (36%) was more explained than that of the abundant (29%). The phylogeny of rare bacteria was equally explained by local factors (soil and vegetation) and geospatial distance (11.5% and 11.9% respectively), while that of the abundant was more explained by geospatial distance (22.1%) than local factors (11.3%). Furthermore, a substantially tighter connection between the community phylogeny and composition was observed in rare (R2 = 0.65) than in abundant bacteria (R2 = 0.08). Our study provides novel insights into the assembly processes and biographical patterns of rare and abundant bacteria in dryland soils.

Time-Course Transcriptome of Parageobacillus thermoglucosidasius DSM 6285 Grown in the Presence of Carbon Monoxide and Air.

Parageobacillus thermoglucosidasius is a metabolically versatile, facultatively anaerobic thermophile belonging to the family Bacillaceae. Previous studies have shown that this bacterium harbours co-localised genes coding for a carbon monoxide (CO) dehydrogenase (CODH) and Ni-Fe hydrogenase (Phc) complex and oxidises CO and produces hydrogen (H2) gas via the water-gas shift (WGS) reaction. To elucidate the genetic events culminating in the WGS reaction, P. thermoglucosidasius DSM 6285 was cultivated under an initial gas atmosphere of 50% CO and 50% air and total RNA was extracted at ~8 (aerobic phase), 20 (anaerobic phase), 27 and 44 (early and late hydrogenogenic phases) hours post inoculation. The rRNA-depleted fraction was sequenced using Illumina NextSeq, v2.5, 1x75bp chemistry. Differential expression revealed that at 8 vs 20, 20 vs 27 and 27 vs 44 hours post inoculation, 2190, 2118 and 231 transcripts were differentially (FDR < 0.05) expressed. Cluster analysis revealed 26 distinct gene expression trajectories across the four time points. Of these, two similar clusters, showing overexpression at 20 relative to 8 hours and depletion at 27 and 44 hours, harboured the CODH and Phc transcripts, suggesting possible regulation by O2. The transition between aerobic respiration and anaerobic growth was marked by initial metabolic deterioration, as reflected by up-regulation of transcripts linked to sporulation and down-regulation of transcripts linked to flagellar assembly and metabolism. However, the transcriptome and growth profiles revealed the reversal of this trend during the hydrogenogenic phase.

Characterization and homology modelling of a novel multi-modular and multi-functional Paenibacillus mucilaginosus glycoside hydrolase.

Glycoside hydrolases, particularly cellulases, xylanases and mannanases, are essential for the depolymerisation of lignocellulosic substrates in various industrial bio-processes. In the present study, a novel glycoside hydrolase from Paenibacillus mucilaginosus (PmGH) was expressed in E. coli, purified and characterised. Functional analysis indicated that PmGH is a 130 kDa thermophilic multi-modular and multi-functional enzyme, comprising a GH5, a GH6 and two CBM3 domains and exhibiting cellulase, mannanase and xylanase activities. The enzyme displayed optimum hydrolytic activities at pH 6 and 60 °C and moderate thermostability. Homology modelling of the full-length protein highlighted the structural and functional novelty of native PmGH, with no close structural homologs identified. However, homology modelling of the individual GH5, GH6 and the two CBM3 domains yielded excellent models based on related structures from the Protein Data Bank. The catalytic GH5 and GH6 domains displayed a (ß/α)8 and a distorted seven stranded (ß/α) fold, respectively. The distinct homology at the domain level but low homology of the full-length protein suggests that this protein evolved by exogenous gene acquisition and recombination.

The Functional Potential of the Rhizospheric Microbiome of an Invasive Tree Species, Acacia dealbata.

Plant-microbe interactions mediate both the invasiveness of introduced plant species and the impacts that they have in invaded ecosystems. Although the phylogenetic composition of the rhizospheric microbiome of Acacia dealbata (an invasive Australian tree species) has been investigated, little is known about the functional potential of the constituents of these altered microbial communities. We used shotgun DNA sequencing to better understand the link between bacterial community composition and functional capacity in the rhizospheric microbiomes associated with invasive A. dealbata populations in South Africa. Our analysis showed that several genes associated with plant growth-promoting (PGP) traits were significantly overrepresented in the rhizospheric metagenomes compared to neighbouring bulk soils collected away from A. dealbata stands. The majority of these genes are involved in the metabolism of nitrogen, carbohydrates and vitamins, and in various membrane transport systems. Overrepresented genes were linked to a limited number of bacterial taxa, mostly Bradyrhizobium species, the preferred N-fixing rhizobial symbiont of Australian acacias. Overall, these findings suggest that A. dealbata enriches rhizosphere soils with potentially beneficial microbial taxa, and that members of the genus Bradyrhizobium may play an integral role in mediating PGP processes that may influence the success of this invader when colonizing novel environments.

Comparative genomic analysis of Parageobacillus thermoglucosidasius strains with distinct hydrogenogenic capacities.

BACKGROUND: The facultatively anaerobic thermophile Parageobacillus thermoglucosidasius produces hydrogen gas (H2) by coupling CO oxidation to proton reduction in the water-gas shift (WGS) reaction via a carbon monoxide dehydrogenase-hydrogenase enzyme complex. Although little is known about the hydrogenogenic capacities of different strains of this species, these organisms offer a potentially viable process for the synthesis of this alternative energy source. RESULTS: The WGS-catalyzed H2 production capacities of four distinct P. thermoglucosidasius strains were determined by cultivation and gas analysis. Three strains (DSM 2542T, DSM 2543 and DSM 6285) were hydrogenogenic, while the fourth strain (DSM 21625) was not. Furthermore, in one strain (DSM 6285) H2 production commenced earlier in the cultivation than the other hydrogenogenic strains. Comparative genomic analysis of the four strains identified extensive differences in the protein complement encoded on the genomes, some of which are postulated to contribute to the different hydrogenogenic capacities of the strains. Furthermore, polymorphisms and deletions in the CODH-NiFe hydrogenase loci may also contribute towards this variable phenotype. CONCLUSIONS: Disparities in the hydrogenogenic capacities of different P. thermoglucosidasius strains were identified, which may be correlated to variability in their global proteomes and genetic differences in their CODH-NiFe hydrogenase loci. The data from this study may contribute towards an improved understanding of WGS-catalysed hydrogenogenesis by P. thermoglucosidasius.

LEA Proteins and the Evolution of the WHy Domain.

The late embryogenesis abundant (LEA) family is composed of a diverse collection of multidomain and multifunctional proteins found in all three domains of the tree of life, but they are particularly common in plants. Most members of the family are known to play an important role in abiotic stress response and stress tolerance in plants but are also part of the plant hypersensitive response to pathogen infection. The mechanistic basis for LEA protein functionality is still poorly understood. The group of LEA 2 proteins harbor one or more copies of a unique domain, the water stress and hypersensitive response (WHy) domain. This domain sequence has recently been identified as a unique open reading frame (ORF) in some bacterial genomes (mostly in the phylum Firmicutes), and the recombinant bacterial WHy protein has been shown to exhibit a stress tolerance phenotype in Escherichia coli and an in vitro protein denaturation protective function. Multidomain phylogenetic analyses suggest that the WHy protein gene sequence may have ancestral origins in the domain Archaea, with subsequent acquisition in Bacteria and eukaryotes via endosymbiont or horizontal gene transfer mechanisms. Here, we review the structure, function, and nomenclature of LEA proteins, with a focus on the WHy domain as an integral component of the LEA constructs and as an independent protein.