搜索结果：Extremophiles

Extremophiles are microorganisms thriving under extreme environmental conditions like high temperature, high salt concentration, very low temperature, varying pH and pressure, etc. Thermophiles are types of extremophiles that survive under very high temperatures ranging from 45 °C to 122 °C. This study provides information about thermophilic isolate from Hammam K'Sana, commonly called Fraksa, hot spring of Algeria at 60-70 °C. One of the isolates was used for the extraction of exopolysaccharides after its screening and biochemical characterisation. Additionally, the lyophilised product obtained was further analysed for total sugar estimation. The FTIR analysis revealed the presence of different functional groups such as hydroxyl, C-H stretching, vibration of aliphatic CH2 and glycosidic linkage, thus proving that the product obtained from bacteria was an exopolysaccharide. XRD graph shows that the product is amorphous in nature. Based on 16S rRNA sequence analysis, the isolate obtained from Algeria had close resemblance with Bacillus licheniformis strain (VTM4R61). This study establishes the capability of thermophilic Bacillus licheniformis strain HSK4 isolated from the Hammam K’Sana hot spring, Algeria, for the manufacture of beneficial exopolysaccharides (EPS). The characterized EPS exhibited important structural properties and may have important applications in biotechnology, pharmaceuticals, etc. The work also highlights hot spring extremophiles as promising sources of novel and justifiable biomolecules.

NASA cleanrooms, which are critical for assembling space mission components, are maintained under stringent decontamination protocols to minimize biological contamination. These environments are characterized by nutrient-poor and oligotrophic conditions, leading to low microbial loads. Despite extensive cleaning, oligotrophs capable of surviving in such conditions continue to persist, often remaining undetected due to their low abundance, resistance to environmental stresses, and difficulties in biomolecule extraction. Even with shotgun metagenome sequencing technologies, these microbes may go undetected or be underrepresented due to their robust cell walls and the absence of reference genomes in publicly available databases. Over a 6-month study of Mars 2020 mission cleanrooms, 182 bacterial strains belonging to 19 families were identified using a whole-genome sequencing (WGS) approach. Among these, 14 novel Gram-positive species were discovered, including eight spore formers. Though the novel species comprised only 0.001% of the sequencing data, their successful cultivation allowed for functional characterization. Through WGS data mining, genomic traits associated with resilience in extreme conditions were revealed. These species were found to be involved in nitrogen cycling, carbohydrate metabolism, and radiation resistance, traits essential for survival in extreme environments. Furthermore, 12 biosynthetic gene clusters were identified, including those linked to ectoine and [Formula: see text]-poly-L-lysine production, suggesting potential biotechnological applications. These findings highlight the hidden microbial diversity within cleanrooms and emphasize the necessity of advanced detection strategies. A better understanding of these microbes will provide insights into extremophiles with applications in biotechnology, medical research, and life support systems for future space exploration missions.IMPORTANCEDespite strict decontamination protocols, NASA cleanrooms harbor low-biomass microbial communities adapted to nutrient-poor environments. These oligotrophic microbes often go undetected in shotgun metagenomics methods due to their low abundance, resistance to lysis, and lack of reference genomes. Standard shotgun metagenome sequencing methods fail to retrieve them, as dominant microbial DNA overshadows rare species. Over 6 months of monitoring Mars 2020 mission cleanrooms, 182 bacterial strains from 19 families were identified, including 14 novel Gram-positive species, 8 of which were spore formers. Though present at 0.001% abundance in sequencing data, we successfully cultured them, enabling functional characterization. These microbes exhibited roles in nitrogen cycling, carbohydrate metabolism, and radiation resistance, with 12 biosynthetic gene clusters linked to ectoine and [Formula: see text]-poly-L-lysine production. These findings highlight the previously underestimated microbial diversity in cleanrooms and emphasize the need for advanced detection strategies to explore extremophiles with applications in biotechnology and space exploration.

Pch-GlmA is a hyperthermophilic GH35 exo-β-d-glucosaminidase whose structure closely resembles its archaeal homologs, yet its functional behavior differs markedly. Calorimetric and fluorimetric temperature scans consistently reveal a complex thermodynamic profile of the enzyme, characterized by distinct thermal transitions. The freshly purified protein appears to be monomeric and required thermal annealing to attain its biologically relevant dimeric state. Catalytic activity is observed only above 75 °C, where the enzyme specifically hydrolyses the glycosidic bond of GlcN-GlcNAc. These findings support a sequential role for Pch-GlmA alongside Pch-Dac in the processing of chitin-derived carbohydrates. Comparison with related GlmA proteins demonstrates that substantial structural similarity does not necessarily translate into equivalent enzymatic properties and that hyperthermophilic enzymes may operate within narrow temperature ranges. Overall, this work underscores the importance of experimental validation when interpreting or predicting the activity of enzymes derived from extremophiles.

Psychrophilic organisms are able to grow at temperatures down to -15 °C, while hyperthermophiles can multiply at temperatures up to 122 °C. What structural changes in extremophile proteins are needed to maintain stable and biochemically active structures under such conditions? Understanding how such extremophiles accomplish this is relevant for human health, biotechnology, and our search for life elsewhere in the universe. The purpose of the current study is to report and compare the structures of four rubredoxins (Rds), the first ever two experimental psychrophile bacteria structures (from Gram-positive Clostridium psychrophilum and Gram-negative Polaromonas glacialis) and two hyperthermophiles from the Gram-negative Thermotoga maritima bacterium and the archaeon Pyrococcus yayanosii, also a piezophile, as part of a program to understand structural variations that support both stability and function under extreme conditions. These structures were obtained using synchrotron radiation X-ray diffraction at 100 K. All four structures had the expected overall rubredoxin fold. Rubredoxin from the only aerobic psychrophilic bacterium Polaromonas glacialis had larger variations in sequence and structure, whereas the other psychrophilic bacterium showed properties closely related to hyperthermophile rubredoxins. Multi-subunit structures showed similar RMSD variability independent from their thermal adaptation status. We propose including functional information in the analysis since temperature optimization may not be the only determinant for a specific protein adaptation.

Aminoglycoside resistance is commonly mediated by enzymatic modification, target alteration, or efflux mechanisms; however, acquired resistance has not been characterized in radiation-resistant Deinococcus species. Here, we investigated the occurrence and genomic context of acquired aminoglycoside resistance genes in all publicly available Deinococcus radiodurans genomes. A total of 19 genomes were screened using ResFinder and CARD, followed by comparative genomic analyses. The aadA1 gene was identified in two genomes, being located on the plasmid pSP1 in strain R1 dM1, a known shuttle vector used for genetic manipulation. In contrast, aadA1 was found on a chromosomal contig in strain DRR11, suggesting a possible assembly artifact. Additionally, the aph(3')-Ia gene was detected in three genomes within a conserved chromosomal region that lacks this gene in reference strains. Sequence similarity analyses indicated that aph(3')-Ia is associated with laboratory vectors, being consistent with a potential non-natural origin. Considering the high recombination capacity and genomic plasticity of D. radiodurans, these findings suggest that the detected aminoglycoside resistance genes may be derived from laboratory constructs, potentially combined with assembly inconsistencies or chromosomal integration events. Therefore, this study highlights the importance of integrating genomic context with molecular and evolutionary plausibility to avoid misinterpretation of antimicrobial resistance in extremophiles and model organisms, and underscores the importance of complementary raw-read analyses to distinguish natural acquisition from technical or laboratory-derived origins.

Industrial activities and legacy contamination have generated metal-laden soils, radionuclide plumes, solvent-saturated sediments, and acidified pollutants. These are complex, hostile matrices where chemical treatments often redistribute rather than eliminate hazards, and where conventional mesophilic microbes cannot survive. Extremophiles, particularly species within the genus Deinococcus, represent a promising alternative for such environments. Their exceptional DNA repair systems and oxidative-stress resistance mechanisms enable metabolic activity under extreme conditions including ionizing radiation, prolonged desiccation, reactive oxygen species, and nutrient limitation. Deinococcus cells and biofilms adsorb metals through surface binding, and engineered strains can be designed to express redox pathways that convert soluble contaminants into insoluble, more readily recoverable forms. Deinococcus combines in situ applicability with minimal site preparation, exceptional stress resilience, and genetic adaptability, making it a strong candidate for bioremediation in environments resistant to conventional methods. This review explores the innate resilience of Deinococcus, its potential applications in bioremediation, and the prospects for enhancing its enzymatic repertoire through genetic engineering, culminating in a discussion of the challenges associated with scale-up and regulatory approval.

The Antarctic lichen Umbilicaria antarctica exhibits exceptional resilience to extreme cold, enabling survival in harsh polar environments. This study investigates the molecular and structural adaptations underlying its tolerance to subzero temperatures. Nuclear Magnetic Resonance analysis showed that at intermediate hydration level, water undergoes a transition from loosely bound to more strongly bound states between - 17 °C and - 24 °C indicating a non-cooperative water immobilization process rather than conventional freezing. Activation energy and average distances between relaxing proton pairs were determined using the Bloembergen-Purcell-Pound (BPP) model. Differential Scanning Calorimetry showed that freezing strongly depends on hydration, with all thermal peaks occurring below - 10 °C, confirming the presence of supercooled water. Heating protocols incorporating isothermal holding steps revealed an additional peak, consistent with diffusion of supercooled water toward pre-existing ice crystallites. Scanning Electron Microscopy detected sub-micrometer compartments within the thallus that physically confine water and solutes. This confinement-synergy effect stabilizes supercooled water, suppresses ice nucleation, and modulates molecular mobility, playing an important role in freezing avoidance. This integrative approach advances our understanding of cold tolerance mechanisms and highlights how coupled structural confinement and physicochemical interactions govern water behavior in extremophiles, offering broader insight into adaptation strategies in polar environments.

Thermophilic cyanobacteria and microalgae have a set of coordinated structural and molecular changes that allow them to survive under elevated temperatures. All these features make are their thermostable enzymes, strong stress response systems, and high-capacity carbon-fixation systems that make these organisms interesting candidates of biotechnological use and sustainability. Cyanobacteria and thermophilic microalgae are a unique group of extremophiles that can survive high temperatures and complex environments. Their morphological, physiological, and evolutionary characteristics enable them to survive in hot springs, arid soils, geothermal environments, and hydrophilic ecosystems. This involves production of heat-stable enzymes, osmolytes, pigments, and protective biomolecules, and increased thermostability of phycobilisomes, reliable repair of photosystem II components, and structural changes of photosystems. Microalgae and cyanobacteria exhibit remarkable morphological plasticity, transforming between unicellular, colonial, and filamentous forms while producing specialized cells like heterocysts, spores, and dormant vegetative cells to survive in various environments. Further, their ecological resilience is enhanced by adaptations to oxidative stress, nutrient limitation, UV radiation, and desiccation. These organisms have great potential for industrial biotechnology, particularly biofuels, bioprocessing, carbon capture, bioremediation, and the synthesis of high-value compounds, due to their unique thermostable enzymes, heat-stable pigments, and carbon fixation efficiency. This review highlights current understanding of the phylogeny, stress adaptation mechanisms, and ecological significance of thermophilic microalgae and cyanobacteria, emphasizing their growing importance in sustainable biotechnology.

High-altitude regions of the Pangi-Chamba Himalayas (PCH) provide a distinctive environment for isolating extremophilic lignocellulolytic bacteria. This study reports the isolation of lignocellulolytic enzyme-producing bacteria from decaying wood samples. Among 54 bacterial isolates, 24 demonstrated lignocellulose hydrolysis potential, producing laccase, xylanase, and cellulase enzymes. Eight morphologically distinct isolates belonging to the phylum Bacillota were selected for further experiments. Quantitative analysis identified Bacillus sp. PCH491 as an efficient producer of xylanase using alkaline-pretreated wheat straw, whereas Bacillus sp. PCH494 produced laccase using alkaline-pretreated sugarcane bagasse. Notably, Bacillus sp. PCH492 produced multiple enzymes, laccase, xylanase, and cellulase, using various agro-residues. Further, characterization of laccase and xylanase enzymes revealed activity across a broad pH (4.0-12.0) and temperature (4-90 ℃). Xylanase from Bacillus sp. PCH491 showed maximum activity (38.86 IU/mL) at pH 7.0 and 50 ℃, whereas laccase from Bacillus sp. PCH494 reached peak activity (31.20 IU/mL) at pH 3.0 and 50 ℃. SEM and FTIR analyses confirmed significant structural and functional group modifications in the biomass, highlighting these high-altitude isolates as robust candidates for industrial biorefineries.

The Na⁺/H⁺ antiporter (NHX) gene family in plants encodes proteins that maintain ion homeostasis, particularly under salt stress, by exchanging Na⁺ or K⁺ for H⁺ across cellular membranes. In cultivated barley (Hordeum vulgare L.), NHX genes have been only partially characterized. In this study, we conducted a genome-wide identification of NHX genes in barley, examining their evolutionary relationships, gene structure, and expression patterns under salt stress (200 mM NaCl) in two genotypes differing in salinity tolerance. Seven genes were identified in the H. vulgare genome, and they are unevenly distributed across chromosomes 2 H, 3 H, 4 H, 5 H, and 7 H. Phylogenetic analysis showed that these genes group into three major classes: Vac (HvNHX1, HvNHX2 and HvNHX3), Endo (HvNHX4, HvNHX5 and HvNHX6), and PM (HvNHX7/HvSOS1). Furthermore, exon-intron organization and conserved motif composition were highly conserved within each class. Vac-class NHX proteins were found to contain an amiloride-binding site in TM3 within their N-terminal region. Promoter analysis revealed that HvNHX1, HvNHX5, HvNHX6, and HvNHX7 possess the highest number of abscisic acid (ABA)-responsive elements (ABREs), suggesting potential regulation via the ABA signaling pathway. The protein-protein interaction (PPI) network indicated that several HvNHX proteins interact with HKT, GORK, CHX and KEA partners. Finally, the RT-qPCR analysis revealed a differential expression of NHX genes between the two contrasting barley genotypes in both roots and leaves under salinity. Our findings provide valuable insights into candidate genes that may be targeted in future genetic engineering strategies to enhance salinity tolerance in barley.

Microorganisms present in the rhizosphere of plants from extreme environments have become a subject of great interest as an alternative to chemical fertilizers for sustainable agriculture. This study focused on the isolation, identification and characterization of extremophilic rhizospheric fungi strains present in a habitat with challenging environmental conditions in terms of temperature, pH, and heavy metal concentrations. Studies were conducted with the aim of finding new microorganisms for the development of novel, robust inoculants that meet the agricultural needs of Solanum lycopersicum, a crop consumed worldwide that, at least in Mexico can be exposed to heat shock in certain seasons. All the strains showed at least five plant growth promoting traits. Noticeably two of the isolated strains (R_34 and R_40) produced indole related compounds (probably indoleacetic acid (IAA)); others hydrolytic enzymes (cellulases, xylanases, and chitinases), as well as siderophores and showed the ability to solubilize inorganic phosphate. All strains reduced the progression of infection caused by Botrytis cinerea on S. lycopersicum leaves and fruits compared to the control, and they also inhibited the growth of various phytopathogenic fungi under in vitro conditions, suggesting an important role in biological control. The microorganisms were identified at the species level through phylogenetic analysis. The fungal strains belonged to the genus Trichoderma sp., Penicillium sp., and Aspergillus sp. In addition, these fungi demonstrated the ability to enhance germination rates, and overall plant growth in S. lycopersicum compared to controls. This research demonstrates that extremophilic fungi can serve as effective probiotics for crops in regions affected by climate variability and heatwaves.

This study investigated the potential of native rhizobacteria from the Lut Desert, one of the hottest and most arid regions on Earth, to enhance drought tolerance in Maize (Zea mays L.). Bacterial isolates were screened for abiotic stress tolerance and plant growth-promoting traits. The selected strain, THU2, which demonstrated minimal growth inhibition under drought, heat, and salinity stress, was used in comprehensive greenhouse and field experiments under both optimal and water-deficit conditions. Results revealed that THU2 inoculation significantly improved maize growth and physiological performance, increasing shoot fresh weight by approximately 40-50% under optimal conditions and by over 100% under water-deficit conditions compared to mock. Key mechanisms identified included: (1) root and xylem modifications that improved water uptake and transport; (2) stomatal regulation leading to enhanced water-use efficiency and photosynthetic rate; and (3) biochemical protection through elevated proline content (up to 53% increase) and reduced oxidative damage (up to 35% reduction in MDA). Field trials confirmed the greenhouse findings, with THU2-inoculated plants showing superior growth, higher photosynthetic efficiency, and increased yield under drought stress. This research demonstrates that the extreme-adapted bacterium THU2 is a highly effective bio-inoculant, offering a sustainable strategy to improve crop resilience in water-limited environments.

Thermo-physical perturbation is expected to weaken protein stability and assembly. Yet, in the biological context, chaperones such as heat shock proteins (HSPs) must counter perturbative effects to preserve proteostasis. Herein, we report that the sHSP14, a small heat shock protein from the extremophile Sulfolobus, inverts this paradigm through thermal reinforcement. Fully atomistic in silico sampling is exploited to reveal that elevated temperatures enhance dimeric stability via enthalpic consolidation that persists even at high salinity. This archaeal chaperone operating with minimal molecular machinery achieves robustness through elegant design: β-strand swapping creates topological architecture, while a strategic charged residue network (Arg17, Asp28, Arg66, Asp41, Arg79, Lys74) and nearly 40 preserved hydrogen bonds maintain stabilization even upon temperature elevation. These findings redefine our understanding of extremophile adaptation and offer blueprints for engineering next-generation thermostable biomolecules.

Halotolerant microorganisms are promising cell factories for industrial biomanufacturing because they combine physiological robustness with practical advantages, including contamination-resistant fermentation, reduced sterilization requirements, and compatibility with saline feedstocks. However, the metabolic burden of stress adaptation, together with regulatory redundancy and pathway complexity, often limits production efficiency and genetic stability. Simplified metabolic pathway design has therefore emerged as a key strategy to improve halotolerant cell factories. Here, we review recent advances from three complementary perspectives: simplified chassis construction through genome streamlining and deletion of competing pathways; simplified pathway design through modularization and orthogonalization; and enabling tools, including genetic transformation, multiplex genome editing, dynamic regulation, evolutionary and computational approaches. Together, these developments define a conceptual and practical framework for rational simplification of halotolerant metabolism, providing design principles for both current industrial hosts and emerging extremophilic chassis.

Despite their vital physiological roles, oxidative imbalance caused by reactive oxygen, nitrogen, sulphur, and chlorine species damages essential body macromolecules such as proteins, lipids, and nucleic acids through oxidative stress. This stress is strongly associated with cancer, inflammation, neurological and cardiovascular disorders, and other chronic human diseases. Therefore, antioxidants, natural or synthetic, that counteract oxidative damage are important, with increasing interest in their use within the pharmaceutical, food, and cosmetic industries. However, due to toxicity concerns with the synthetic variants, natural antioxidants are increasingly preferred. Extremophile-derived antioxidants, such as superoxide dismutases, catalases, peroxidases, carotenoids, and melanin, are of renewed interest due to their remarkable stability, robustness, and potency under extreme conditions of temperature, pH, and salinity. These make them better than many mesophile-derived antioxidants and excellent candidates for cost-effective biotechnological, research, and industrial processes that require high operational efficiency. This review summarises key classes of selected enzymatic and pigment antioxidants, their mechanisms of action, and their industrial relevance, with a focus on extremophilic microalgae, bacteria, and fungi. The benefits of extremophilic antioxidants are discussed alongside their current applications and existing challenges, including the need to develop efficient delivery systems, scalability issues, and limited characterisation.

Transposable elements (TEs) are major drivers of genome plasticity, yet their diversity, dynamics, and evolutionary history remain poorly understood in archaea, which share a more recent common ancestry with eukaryotes than with bacteria. To address this issue, we systematically characterized insertion sequences (ISs), the predominant class of prokaryotic TEs, together with eukaryotic-like transposons (ELTs) across 17,237 archaeal genomes from 21 archaeal phyla. In this study, IS200/IS605 was the most widespread and abundant IS family across archaeal genomes. Although most archaeal phyla exhibited low IS and ELT content, we identified lineage-specific expansions and high IS family diversity within extremophilic groups, particularly the Thermoproteota and Halobacteriota. Analysis of complete genomes identified an IS-rich lineage within Sulfolobaceae, where genome size positively correlated with IS abundance. In the genus Saccharolobus, the increase in IS content was driven predominantly by the expansion of the ISH3 family. Notably, genes flanking these ISH3 insertions were frequently associated with environment-related metabolic functions, suggesting that ISH3 proliferation may contribute to adaptation to high-temperature environments. Sequence analysis further revealed overlaps between IS and ELT elements, including IS630-Tc1/mariner and IS3/IS481-LTR/Gypsy associations, while phylogenetic analysis of DDE transposases indicated extensive cross-domain gene exchange. Collectively, this large-scale survey illuminates the diversity, distribution, and evolutionary dynamics of transposable elements in archaea, providing new insights into their evolutionary connections with prokaryotes and eukaryotes.

Quinoa, a resilient crop adapted to marginal environments, offers a promising alternative under water-limited conditions. To gain new insights into its drought tolerance, we combined physiological analyses with quantitative proteomics under progressive drought (1-2 weeks) and subsequent recovery (2 weeks). Drought stress induced significant reductions in biomass (56%) and relative water content (46%) after two weeks, with leaf osmotic potential decreasing by up to 48%. However, plants exhibited strong recovery in these parameters upon rehydration. Proteomic analysis identified 114 differentially abundant proteins between drought treatments and control. Proteins involved in cell defense and cytoskeleton organization including S-adenosylmethionine synthetase, caffeoyl-CoA O-methyltransferase, actin, and Exocyst complex component EXO84A, showed an increase under short-term drought conditions. Antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) increased during prolonged drought and further during recovery, while heat shock proteins (HSP90) accumulated under stress and declined after rewatering, supporting protein stability and oxidative defense. Multiple ribulose bisphosphate carboxylase large and small subunits (RuBisCO) showed increased abundance under drought and further increased during recovery, while oxygen-evolving enhancer proteins (OEE1, OEE2) accumulated early (D1W), helping to stabilize PSII under stress. Interestingly, key proteins involved in amino acid metabolism, including ACT domain-containing protein (ACR11), glutamine synthetase, and Ferredoxin-dependent glutamate synthase (Fd-GOGAT), were identified as regulators of nitrogen assimilation and oxidative stress regulation. Betaine aldehyde dehydrogenase was decreased under stress and increased during recovery, reflecting osmoprotectant accumulation. This study, integrating physiological and proteomic data, demonstrates that quinoa deploys immediate protective mechanisms while activating adaptive processes related to stress memory and recovery-associated metabolic changes, highlighting its resilience under water deficit.