Chromium (Cr) compounds are usually toxins and exist abundantly in two different forms, Cr(VI) and Cr(III), in nature. Their contamination in any environment is a major problem. Many extreme ...environments including cold climate, warm climate, acidic environment, basic/alkaline environment, hypersaline environment, radiation, drought, high pressure, and anaerobic conditions have accumulated elevated Cr contamination. These harsh physicochemical conditions associated with Cr(VI) contamination damage biological systems in various ways. However, several unique microorganisms belonging to phylogenetically distant taxa (bacteria, fungi, and microalgae) owing to different and very distinct physiological characteristics can withstand extremities of Cr(VI) in different physicochemical environments. These challenging situations offer great potential and extended proficiencies in extremophiles for environmental and biotechnological applications. On these issues, the present review draws attention to Cr(VI) contamination from diverse extreme environmental regions. The study gives a detailed account on the ecology and biogeography of Cr(VI)-resistant microorganisms in inhospitable environments, and their use for detoxifying Cr(VI) and other applications. The study also focuses on physiological, multi-omics, and genetic engineering approaches of Cr(VI)-resistant extremophiles.
Energy-converting hydrogenases (Ech) are ancient, membrane-bound enzymes that use reduced ferredoxin (Fd) as an electron donor to reduce protons to molecular H2. Experiments with whole cells, ...membranes and vesicle-fractions suggest that proton reduction is coupled to proton translocation across the cytoplasmatic membrane, but this has never been demonstrated with a purified enzyme. To this end, we produced a His-tagged Ech complex in the thermophilic and anaerobic bacterium Thermoanaerobacter kivui. The enzyme could be purified by affinity chromatography from solubilized membranes with full retention of its eight subunits, as well as full retention of physiological activities, i.e., H2-dependent Fd reduction and Fd2--dependent H2 production. We found the purified enzyme contained 34.2 ± 12.2 mol of iron/mol of protein, in accordance with seven predicted 4Fe-4S-clusters and one Ni-Fe-center. The pH and temperature optima were at 7 to 8 and 66 °C, respectively. Notably, we found that the enzymatic activity was inhibited by N,N′-dicyclohexylcarbodiimide, an agent known to bind ion-translocating glutamates or aspartates buried in the cytoplasmic membrane and thereby inhibiting ion transport. To demonstrate the function of the Ech complex in ion transport, we further established a procedure to incorporate the enzyme complex into liposomes in an active state. We show the enzyme did not require Na+ for activity and did not translocate 22Na+ into the proteoliposomal lumen. In contrast, Ech activity led to the generation of a pH gradient and membrane potential across the proteoliposomal membrane, demonstrating that the Ech complex of T. kivui is a H+-translocating, H+-reducing enzyme.
Virus research has advanced significantly since the discovery of the tobacco mosaic virus (TMV), the characterization of its infection mechanisms and the factors that determine their pathogenicity. ...However, most viral research has focused on pathogenic viruses to humans, animals and plants, which represent only a small fraction in the virosphere. As a result, the role of most viral genes, and the mechanisms of coevolution between mutualistic viruses, their host and their environment, beyond pathogenicity, remain poorly understood. This review focuses on general aspects of viruses that interact with extremophile organisms, characteristics and examples of mechanisms of adaptation. Finally, this review provides an overview on how knowledge of extremophile viruses sheds light on the application of new tools of relevant use in modern molecular biology, discussing their value in a biotechnological context.
ABSTRACT
When it comes to the investigation of key ecosystems in the world, we often omit salt from the ecological recipe. In fact, despite occupying almost half of the volume of inland waters and ...providing crucial services to humanity and nature, inland saline ecosystems are often overlooked in discussions regarding the preservation of global aquatic resources of our planet. As a result, our knowledge of the biological and geochemical dynamics shaping these environments remains incomplete and we are hesitant in framing effective protective strategies against the increasing natural and anthropogenic threats faced by such habitats. Hypersaline lakes, water bodies where the concentration of salt exceeds 35 g/l, occur mainly in arid and semiarid areas resulting from hydrological imbalances triggering the accumulation of salts over time. Often considered the ‘exotic siblings’ within the family of inland waters, these ecosystems host some of the most extremophile communities worldwide and provide essential habitats for waterbirds and many other organisms in already water‐stressed regions. These systems are often highlighted as natural laboratories, ideal for addressing central ecological questions due to their relatively low complexity and simple food web structures. However, recent studies on the biogeochemical mechanisms framing hypersaline communities have challenged this archetype, arguing that newly discovered highly diverse communities are characterised by specific trophic interactions shaped by high levels of specialisation. The main goal of this review is to explore our current understanding of the ecological dynamics of hypersaline ecosystems by addressing four main research questions: (i) why are hypersaline lakes unique from a biological and geochemical perspective; (ii) which biota inhabit these ecosystems and how have they adapted to the high salt conditions; (iii) how do we protect biodiversity from increasing natural and anthropogenic threats; and (iv) which scientific tools will help us preserve hypersaline ecosystems in the future? First, we focus on the ecological characterisation of hypersaline ecosystems, illustrate hydrogeochemical dynamics regulating such environments, and outline key ecoregions supporting hypersaline systems across the globe. Second, we depict the diversity and functional aspects of key taxa found in hypersaline lakes, from microorganisms to plants, invertebrates, waterbirds and upper trophic levels. Next, we describe ecosystem services and discuss possible conservation guidelines. Finally, we outline how cutting‐edge technologies can provide new insights into the study of hypersaline ecology. Overall, this review sheds further light onto these understudied ecosystems, largely unrecognised as important sources of unique biological and functional diversity. We provide perspectives for key future research avenues, and advocate that the conservation of hypersaline lakes should not be taken with ‘a grain of salt’.
Viviparity, a reproductive form that supplies nutrients to the embryo during gestation, has repeatedly and independently occurred in multiple lineages of animals. During the convergent evolution of ...viviparity, various modifications of development, structure, and physiology emerged. A new species of nematode,
, was discovered in the alkaline, hypersaline, and arsenic-rich environment of Mono lake. Its reproductive form is viviparity because it is obligately live-bearing and the embryo increases in size during development. However, the magnitude of the increase in size and nutrient provisioning are unclear. We measured egg and embryo sizes at three developmental stages in
.
. Eggs and embryos of
.
at the threefold stage were respectively 2.6- and 3.6-fold larger than at the single-cell stage. We then obtained
embryos at the single-cell, lima bean, and threefold developmental stages and investigated the egg hatching frequency at three different concentrations of egg salt buffer. Removal of embryos from the uterus halted embryonic development at the single-cell and lima bean stages in
irrespective of the solution used for incubation, indicating the provision of nutrients within the uterus. Ultrastructural and permeability evaluation showed that the permeability barrier did not form during embryonic development, resulting in increased molecular permeability. This high permeability caused by the absence of the permeability barrier likely enables supply of nutrients from the mother. The structural and physiological modifications in
.
are like those in other viviparous animals. We conclude that
.
is a viviparous rather than an ovoviviparous nematode.
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will facilitate investigation of the evolution of viviparity in animals.
The snow-covered surfaces of Antarctica comprise an extreme environment that favors the development of life forms with adaptations to adverse low-temperature habitats. The ability to survive and such ...temperatures might involve the production of antifreeze proteins and ice-binding proteins that attenuate the effects of intense cold temperatures. He, we sequenced and reconstructed the nuclear and mitochondrial genomes of the endemic Antarctic fungus Antarctomyces pellizariae UFMGCB 12416. We then have identified a putative ice-binding protein-coding gene, mapped the presence of secondary metabolite gene clusters, and reconstructed the phylogenetic relationships of a A. pellizariae with others Leotiomycetes from the alignment of hundreds of orthologous single-copy proteins. Our results will deepen the understanding of microbial ice-binding proteins and the genomic aspects of psychrophilic fungi.
The GenBank/EMBL/DDBJ accession number for the gene sequence of ice-binding protein from A. pellizariae determined in this study is MN867686. The Whole Genome Shotgun project of strain A. pellizariae UFMGCB 12416 has been deposited at DDBJ/ENA/GenBank under accession WCAA00000000. The version described in this paper is version WCAA01000000. The mitochondrial genome has been deposited under accession MT197497.
The thermal ecology of ectotherm animals has gained considerable attention in the face of human-induced climate change. Particularly in aquatic species, the experimental assessment of critical ...thermal limits (CTmin and CTmax) may help to predict possible effects of global warming on habitat suitability and ultimately species survival. Here we present data on the thermal limits of two endemic and endangered extremophile fish species, inhabiting a geothermally heated and sulfur-rich spring system in southern Mexico: The sulfur molly (Poecilia sulphuraria) and the widemouth gambusia (Gambusia eurystoma). Besides physiological challenges induced by toxic hydrogen sulfide and related severe hypoxia during the day, water temperatures have been previously reported to exceed those of nearby clearwater streams. We now present temperature data for various locations and years in the sulfur spring complex and conducted laboratory thermal tolerance tests (CTmin and CTmax) both under normoxic and severe hypoxic conditions in both species. Average CTmax limits did not differ between species when dissolved oxygen was present. However, critical temperature (CTmax=43.2°C) in P. sulphuraria did not change when tested under hypoxic conditions, while G. eurystoma on average had a lower CTmax when oxygen was absent. Based on this data we calculated both species' thermal safety margins and used a TDT (thermal death time) model framework to relate our experimental data to observed temperatures in the natural habitat. Our findings suggest that both species live near their thermal limits during the annual dry season and are locally already exposed to temperatures above their critical thermal limits. We discuss these findings in the light of possible physiological adaptions of the sulfur-adapted fish species and the anthropogenic threats for this unique system.
Microbial exopolysaccharides (EPSs) exhibit diverse functionalities and offer a variety of structural options that can be altered to fit a specific purpose. EPSs can degrade within the body via ...biological processes, and polysaccharides are regarded as generally safe. More so, microbial EPS is replicable from several known, inexpensive, and plentiful sources. Drug delivery-related research involving polysaccharides have continuously cited minimal to zero cytotoxicity and, where tested, sufficient drug release and a competent release profile. Transdermal drug delivery systems as films not only avoids first-pass metabolism, but also provides pain-free administration, assists patients with dysphagia, has increased patient compliance, can be self-administered, and can be removed at any time. Commonly used synthetic polymers in the field of drug delivery have been related to problems regarding toxicity and immunogenicity, escalating the need for an alternative. Ultimately, the risks while using synthetic polymers could result in serious negative influences involving physiological, physiochemical, and molecular events. Research involving exopolysaccharides from extremophiles is only recently gaining attention. However, commercial use of microbial polysaccharides in other areas as well as the positive results from preliminary research suggests microbial EPSs have a promising future in biomedical engineering and medicine, especially as an alternative to current synthetic polymers.
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Due to their ability to withstand "extreme" conditions, Earth's extremophilic organisms can constrain habitability windows for other planetary systems. However, there are many other considerations to ...microbial growth requirements beyond environmental extremes, such as nutrient availability. Here, we conduct a literature review of the most extremotolerant extremophiles in culture, since working with cultured organisms allows environmental and nutrient variables to be constrained with a high level of specificity. We generated a database that includes the isolation environment, carbon source(s) used, and growth preferences across temperature, pressure, salinity, and pH extremes. We found that the "most extreme" conditions were primarily sustained by heterotrophs, except for hyperthermophiles. These results highlight the importance of considering organic carbon availability when using extremophiles for habitability constraints. We also interrogated polyextreme potential across temperature, pressure, salinity, and pH conditions. Our findings suggest that the investigation of growth tolerance rather than growth optimum may reveal wider habitability parameters. Overall, these results highlight the potential polyextremes, environments, nutrient requirements, and additional analyses that could improve the application of cultured investigations to astrobiology questions.
Extremophilic microorganisms have adopted a variety of ingenious strategies for survival under high or low temperature, extreme pressure, and drastic salt concentrations. A novel application area for ...extremophiles is the use of “extremolytes,” organic osmolytes from extremophilic microorganisms, to protect biological macromolecules and cells from damage by external stresses. In extremophiles, these low molecular weight compounds are accumulated in response to increased extracellular salt concentrations, but also as a response to other environmental changes, e.g., increased temperature. Extremolytes minimize the denaturation of biopolymers that usually occurs under conditions of water stress and are compatible with the intracellular machinery at high (>1 M) concentrations. The ectoines, as the first extremolytes that are produced in a large scale, have already found application as cell protectants in skin care and as protein-free stabilizers of proteins and cells in life sciences. In addition to ectoines, a range of extremolytes with heterogenous chemical structures like the polyol phosphates di-myoinositol-1,1'-phosphate, cyclic 2,3-diphosphoglycerate, and α-diglycerol phosphate and the mannose derivatives mannosylglycerate (firoin) and mannosylglyceramide (firoin-A) were characterized and were shown to have protective properties toward proteins and cells. A range of new applications, all based on the adaptation to stress conditions conferred by extremolytes, is in development.
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