Search Results (117)

DNA-protecting proteins (Dps) are crucial for safeguarding chromosomal DNA in starved cells during the stationary phase under stressful conditions. In previous research, the two Dps proteins in Deinococcus geothermalis, Dgeo_0257 (Dps3) and Dgeo_0281 (Dps1), were found to complement each other in protecting DNA from oxidative damage. This study investigates the physiological changes and transposition of insertion sequences (ISs) in a double-knockout (DK) mutant lacking both dps genes. Comparisons between the wild-type and mutant strains revealed significant phenotypic differences in viability under oxidative stress conditions induced by hydrogen peroxide and ferrous ions, particularly during the stationary phase. Notably, oxidative stress triggered the transposition of the IS families IS701 and IS5, with IS66 being transposed exclusively in the DK mutant into a gene encoding phytoene desaturase. Transcriptomic analysis using RNA-seq revealed substantial fold changes in gene expression across the genome. For example, the dgeo_1459–1460 gene cluster, which encodes a DUF421 domain-containing protein and a hypothetical protein, was highly upregulated under both oxidative and non-oxidative conditions. Interestingly, catalase, encoded by a single gene in D. geothermalis, was upregulated in the DK mutant during the stationary phase, with expression levels exceeding those observed in the single dps gene-deficient mutants. Conversely, a prominent downregulation of the Fur family regulator was detected. These findings highlight the growth phase-dependent physiological adaptation of the dps-DK mutant and reveal a novel IS transposition event of the ISBst12 group involving the IS66 family. Therefore, this study provides new observations into the influence of DNA-protective protein deficiency on oxidative stress responses and IS transposition in D. geothermalis, as well as the regulatory mechanisms of the catalase induction pathway, raising the need for further investigation into the role of OxyR. Full article

The rising popularity of raw goat milk has heightened concerns about its safety. This study examined how differences in milking and cleaning practices influence the quality and microbiota of goat milk from small-scale Oregon farms during July and August. Milk quality was assessed through somatic cell counts (SCCs) and components, while microbiota was evaluated using viable counts and 16S rRNA sequencing. Sequencing revealed a diverse microbial community, dominated by genera such as Staphylococcus, Escherichia-Shigella, and Pseudomonas, with pathogenic taxa like Salmonella and Campylobacter largely absent or detected at negligible levels. Alpha diversity varied significantly among sample types but not across farms, and beta diversity indicated considerable dissimilarity in microbial composition. Importantly, regression models identified significant associations between hygiene practices and bacterial abundance: the absence of glove use and hand sanitation was linked to increased levels of Escherichia-Shigella, Kocuria, Enterococcus, and Corynebacterium, while the use of bleach-chlorhexidine sanitizer was associated with higher Deinococcus. These findings highlight the role of rigorous hygiene protocols in shaping the microbiota of raw goat milk and emphasize the need for targeted practices to minimize contamination risks. Full article

A growing interest is focused on the efficient production of deinoxanthin (DEIX) and its use as a bioactive antioxidant. Here, we produced DEIX from Deinococcus radiodurans and examined how DEIX regulates hydrogen peroxide (H₂O₂)-mediated oxidative behaviors in mouse-derived bone marrow (BM) stromal cells and BM monocytes. We also evaluated whether oral supplementation with DEIX has radioprotective potential against total body irradiation (TBI)-mediated impairments in growth, organs, survival, and hematopoietic development using a mouse model. The direct addition of DEIX recovered H₂O₂-mediated oxidative disorders in the proliferation and the balance between osteoblast and osteoclast activity of the BM-derived cells in a dose-dependent manner. We found that recovery was closely associated with the DEIX’s potencies to remove cellular reactive oxygen species and to restore the expression of key molecules that tightly control bone homeostasis. Long-term oral supplementation with DEIX (25 mg/kg body weight, once per day for 42 consecutive days) protected mice against sub-lethal TBI (5 Gy)-mediated decreases in organ and body weights and lifespan. Supplemental DEIX also inhibited TBI-mediated structural damage in organs and restored endogenous antioxidant defense systems in the liver of TBI-exposed mice. Moreover, supplemental DEIX recovered a dysregulated hematopoietic process in TBI-exposed mice. Collectively, our results introduce an efficient method to produce DEIX and demonstrate its potency to recover oxidative cellular complication in H₂O₂-exposed BM-derived cells. Overall, our findings suggest that DEIX is a great antioxidative molecule to prevent or protect TBI-mediated systemic damages. Full article

The accumulation of high levels of manganese ions complexed with small molecules has been proposed as a pivotal factor contributing to the extraordinary radiation resistance of Deinococcus radiodurans. However, the molecular mechanisms governing the manganese ion homeostasis remain elusive. In this study, we characterize the role of the MntABC transporter system for Mn ion accumulation in D. radiodurans. Its cellular membrane localization is unequivocally demonstrated through fluorescence labeling techniques. Mutation of the protein components of the MntABC led to a significant decrease in intracellular Mn ion accumulation, concomitant with impaired cellular growth, decreased resistance against hydrogen peroxide, and gamma-ray irradiation-induced oxidative stresses, indicating that the MntABC system plays an indispensable role in resistance of D. radiodurans to oxidative stresses. Protein structure modeling and molecular docking are employed to analyze the key active sites of the MntABC proteins and their intermolecular interactions. The results demonstrate that the MntABC system is essential for maintaining Mn ion homeostasis and the oxidative stress resistance of D. radiodurans. Full article

Extracellular vesicles (EVs) derived from bacteria are emerging as potent bioactive carriers that affect host immunity. Deinococcus radiodurans, an extremophilic bacterium with strong antioxidant capacity, produces EVs enriched in deinoxanthin (DX), a carotenoid with a reactive oxygen species–scavenging activity. Here, we assessed the antioxidant activity of D. radiodurans-derived EVs (R1-EVs) in biochemical assays and their immunomodulatory effects on dendritic cells (DCs). R1-EVs exhibited significantly higher antioxidant activity than EVs from a DX-deficient mutant strain (ΔcrtI-EVs), consistent with DX enrichment. Bone marrow-derived DCs treated with R1-EVs in the presence of lipopolysaccharide displayed reduced expression of surface maturation markers and pro-inflammatory cytokines, while interleukin-10 (IL-10) production and antigen uptake were preserved, indicating a tolerogenic phenotype. This tolerogenic program led to decreased proliferation and cytokine production in allogeneic CD4⁺ and CD8⁺ T cells. Mechanistically, R1-EVs inhibited mitogen-activated protein kinase (MAPK) and nuclear factor kappa B (NF-κB) signaling pathways, key regulators of the DC activation. Importantly, IL-10 neutralization reversed these effects, restoring DC and T cell activation. Notably, ΔcrtI-EVs showed weaker antioxidant and immunoregulatory activities. Together, our findings identify R1-EVs as dual-functions, DX- and IL-10-dependent nanoplatform that integrates antioxidant and tolerogenic properties, with potential applications in inflammatory and autoimmune disease control. Full article

In this paper, we analyse the effectiveness of microbubble technology in inactivating/reducing gram-negative, gram-positive, and radiation-resistant bacteria, including Escherichia coli, Bacillus subtilis, and Deinococcus radiodurans, respectively, in model water. Key water quality parameters such as dissolved oxygen, conductivity, pH, and total dissolved solids are recorded and presented to demonstrate their range in the current investigation. The study results indicate a reduction of 95% in E. coli, 100% in D. radiodurans, and 45% in B. subtilis following microbubble treatment. These findings suggest that ambient air microbubbles, generated using a low-cost, reagent-free, and eco-friendly venturi-type microbubble generator, represent a promising technique for reducing bacterial loads in water. Full article

Background: Deinococcus radiodurans, renowned for its exceptional resistance to radiation, provides a robust model for elucidating cellular stress responses and DNA repair mechanisms. Previous studies have established PprI as a key regulator contributing to radiation resistance through its involvement in DNA damage repair pathways, oxidative stress response, and metabolic regulation. Methods: Building upon these foundations, our study employs label-free quantitative (LFQ) proteomics coupled with high-resolution mass spectrometry to systematically map pprI deletion protein networks by comparing the global proteomic profiles of pprI knockout and wild-type D. radiodurans strains. Results: Under stringent screening criteria, we identified 719 significantly higher and 281 significantly lower abundant proteins in the knockout strain compared to wild-type strains. Functional analysis revealed that PprI deficiency disrupts homologous recombination (HR) repair, activates nucleotide excision repair (NER) and base excision repair (BER) as a compensatory mechanism, and impairs Mn/Fe homeostasis and carotenoid biosynthesis, leading to increased oxidative stress. Furthermore, PprI deficiency induces significant metabolic reprogramming, including impaired purine synthesis, compromised cell wall integrity, etc. Conclusions: These proteomic findings delineate the extensive regulatory network influenced by PprI, revealing coordinated perturbations across multiple stress response systems when PprI is absent. Full article

This study systematically evaluates the effects of dietary supplementation with phytogenic feed additive (0.2%, 0.4%, and 0.8%) on white-feathered broilers (n = 88) through a 42-day controlled trial with the weight of approximately 50 g. The experimental design incorporates a triplicate-group-replicated protocol with daily feed intake monitoring, culminating in comprehensive assessments of the growth performance, slaughter traits, meat quality, and cecal microbiome dynamics. The results demonstrated that the 0.8% supplementation significantly enhanced average daily weight gain (p < 0.05), optimized meat characteristics (elevated the redness of meat, reduced pH; p < 0.05), and restructured cecal microbiota by enriching Deinococcus-Thermus, Bacteroidetes, Actinobacteria, and Cyanobacteria (p < 0.05). Based on microbiota-based functional prediction analyses (COG/KEGG/MetaCyc), phytogenic feed additive significantly activated lipid metabolism pathways in broilers. The immunomodulatory correlations between Deinococcus/Thermus/Cyanobacteria and immune indicators suggested their potential immune-enhancing effects mediated through host immune regulation. The findings established the 0.8% phytogenic feed additive as a multifunctional phytogenic additive that synchronously improves zootechnical performance, meat quality, and microbiome homeostasis, offering a scientifically validated strategy for antibiotic-free precision nutrition in sustainable poultry production. Full article

Deinococcus radiodurans is a remarkably unique microorganism, exhibiting extraordinary tolerance to extreme conditions such as ionizing radiation, ultraviolet light, and desiccation. However, the response mechanisms of D. radiodurans under low-temperature stress remain largely unexplored and have yet to be fully elucidated. The DohD protein is a hydrophilic member of the late embryogenesis abundant 3 (LEA3) family of D. radiodurans, playing a pivotal role in abiotic stress adaptation. Bioinformatics analysis revealed that DohD contains tandem repeats and disordered domains, with a remarkably high α-helix content (91.41%). Furthermore, DohD exhibits extremely low homology with other proteins, highlighting its uniqueness to D. radiodurans. Under low-temperature stress (15 °C), the expression of dohD was significantly upregulated (5-fold), regulated by a dual mechanism involving positive control by DrRRA and negative regulation by Csp. Circular dichroism spectroscopy unveiled temperature-dependent structural plasticity: as the temperature increased from 0 °C to 50° C, the α-helix content decreased from 23.5% to 18.7%, while the antiparallel β-sheet content increased from 31.3% to 50.8%. This suggests an α-helix to β-sheet interconversion mechanism as a strategy for thermal adaptation. Additionally, deletion of dohD impaired the tolerance of D. radiodurans to cold, desiccation, oxidative, and high-salt stresses, accompanied by the reduced activities of antioxidant enzymes (SOD, CAT, POD) and the downregulation of related gene expression. This study elucidates the multifunctional role of DohD in stress resistance through structural dynamics, transcriptional regulation, and redox homeostasis, providing valuable insights into the adaptation mechanisms of extremophiles. Full article

Salt stress adversely impacts plant physiology by causing ionic, osmotic, and oxidative stress, ultimately hindering growth and yield. The genus Deinococcus contains unique stress resistance genes, and previous studies have shown that proteins such as IrrE, Csp, and WHy enhance stress tolerance in plants and microbial cells. However, their role in Brassica napus L. (oilseed rape) remains unexamined. In this study, a synthetic stress-resistance module, DICW, was constructed using the Deinococcus-derived genes IrrE, Csp, and WHy and heterologously overexpressed in B. napus to assess its impact on salt tolerance. The results demonstrated that the DICW module significantly improved seed germination and seedling growth under salt stress. Transgenic B. napus plants exhibited reduced membrane damage, higher leaf relative water content, enhanced accumulation of osmoregulatory substances, and elevated antioxidant enzyme activity compared to wild-type plants. Additionally, qRT-PCR analysis revealed the upregulation of stress-related genes (BnRD29A, BnP5CS, BnKIN1, BnLEA1, BnNHX1, and BnSOS1) and antioxidant enzyme-related genes (BnSOD, BnPOD, and BnCAT) in transgenic lines. In conclusion, the DICW module plays a crucial role in enhancing salt tolerance in B. napus by regulating stress responses and antioxidant mechanisms. This study provides valuable molecular insights into improving the survival and growth of B. napus in saline environments. Full article

Cadmium (Cd) and lead (Pb) are the primary hazardous heavy metals that accumulate in crops and pose substantial risks to public health via the food chain. Limiting the migration of these toxic metals from contaminated environments to rice is the most direct and crucial remediation approach. Bioremediation with microorganisms has been extensively utilized for managing heavy metal contamination in the natural environment, and the interplay between microbes and crops is important to alleviate heavy metal stress. Here, we express Lpp-OmpA fused with two metal-binding domains (PbBD and MTT5) in the outer membrane of Deinococcus radiodurans to enhance both Cd and Pb adsorption. Our results showed that the recombinant strain LOPM, which displayed an increased tolerance to both Cd and Pb stress, exhibited a 4.9-fold higher Cd adsorption and 3.2-fold higher Pb adsorption compared to wild-type strain R1. After LOPM cells colonized the rice root, Cd content reduced to 47.0% in root and 43.4% in shoot; Pb content reduced to 55.4% in root and 26.9% in shoot, as compared to the plant’s exposure to Cd and Pb. In addition, cells of LOPM strain colonized on rice roots alleviate Cd- and Pb-induced oxidative stress by reducing ROS levels and enhancing antioxidant enzyme activities in rice. This study supplies a promising application of genetic-engineering extremophile bacteria in reducing heavy metal accumulation and toxicity in rice. Full article

Perchlorate is one of the major inorganic pollutants in the natural environment and the living environment, which is toxic to organisms and difficult to degrade due to its special structure. As previously reported, the Phoenix Mars lander detected approximately 0.6% perchlorate in the Martian soil, indicating challenges for Earth-based life to survive there. Currently, biological approaches using dissimilatory perchlorate-reducing bacteria (DPRB) are the most promising methods for perchlorate degradation. However, the majority of DPRB exhibit limited radiation resistance, rendering them unsuitable for survival on Mars. In this study, we obtained the transcriptome data of Deinococcus deserti, and predicted and identified multiple constitutive expression promoters of D. deserti with varying activities. The top-five most active promoters were separately fused to specific genes involved in the degradation of perchlorate from DPRB Dechloromonas agitata CKB, and transformed into Deinococcus radiodurans R1, forming a novel dissimilatory perchlorate-reducing bacterium, R1−CKB. It exhibited both efficient perchlorate degradation capability and strong radiation resistance, potentially offering a valuable tool for the further enhancement of the Martian atmosphere in the future. Full article

Reactive oxygen species (ROS), byproducts of cellular metabolism and environmental factors, are linked to diseases like cancer and aging. Antioxidant peptides (AOPs) have emerged as effective countermeasures against ROS-induced damage. The Deinococcus genus is well known for its extraordinary resilience to ionizing radiation (IR) and possesses complex antioxidant systems designed to neutralize ROS generated by IR. In this study, we developed four peptides, each containing 9 to 11 amino acids, from the leaderless mRNA (lmRNA) sequences of D. deserti. Lacking a 5′ untranslated region, lmRNAs directly initiate protein synthesis, potentially encoding small peptides such as AOPs. Of the four peptides, Ddes-P3 was found to exhibit significant antioxidant capabilities in vitro, effectively scavenging ABTS radicals. Ddes-P3 provided considerable defense against IR-induced oxidative stress in CHO-K1 cells, demonstrating a notable reduction in ROS production and lipid peroxidation. The peptide’s potential was highlighted by its ability to enhance cell survival and maintain mitochondrial membrane potential under irradiative stress, suggesting its utility as a nontoxic and effective radioprotector in mitigating radiation-induced cellular damage. This study explores the potential role of lmRNA in synthesizing AOPs within Deinococcus. Identifying lmRNAs that encode AOPs could deepen our understanding of their cellular resistance to oxidative stress and pave the way for creating innovative biotechnological and therapeutic AOPs. Full article

Photovoltaic technology has proven to be a reliable, economical, and clean energy source that is capable of adapting to diverse geographical conditions. However, factors such as soiling overshadow these qualities, thus leading to production losses and affecting the profitability of this technology. For these reasons, soiling is a highly studied topic, which involves considering the physicochemical characterization of the deposited material, mitigation strategies, effect predictions, and cleaning mechanisms. However, there is a relatively unexplored area related to the microbiological contribution to soiling. The surface of photovoltaic modules, along with the deposited material and local atmospheric factors, fosters favorable conditions for the colonization of microorganisms. These microorganisms influence the soiling mechanisms and optical properties of photovoltaic modules. This work presents a detailed characterization of the microbial diversity present in the soiling deposited on photovoltaic modules installed in the Atacama Desert. Two study sites were defined: Antofagasta and the Solar Platform of the Atacama Desert, which have warm and cold desert climates, respectively. Mineralogical characterization tests, heavy metal analyses, TOC, and inorganic element analyses were conducted on the deposited material. Additionally, the culturable isolates and the metagenomic DNA of the soiling samples and biofilms grown on standard PV glass were characterized using next-generation sequencing. The results show that the deposited soiling contained a microbiological component that had adapted to extreme desert conditions. The presence of the genera Arthrobacter, Kocuria, and Dietzia were identified in the culturable isolates from Antofagasta, while Arthrobacter and Dietzia were obtained from the Solar Platform of the Atacama Desert. The metagenomic DNA was mainly represented by the genera Pontibacter, Noviherbaspirillum, Massilia, Arthrobacter, Hymenobacter, and Deinococcus at Antofagasta. However, at the Solar Platform of the Atacama Desert, the analyzed samples presented DNA concentrations below 0.5 ng/µL, which made their preparation unviable. At the PSDA, the biofilms formed by the genera Peribacillus and Kocuria were identified, whereas the UA showed a greater abundance of bacteria that favored biofilm formation, including those that belonged to the genera Bacillus, Sporosarcina, Bhargavaea, Mesaobacillus, Cytobacillus, Caldakalibacillus, and Planococcus. Based on these results, we propose a soiling mechanism that considers the microbiological contribution to material cementation. Full article

Radiation protection is an important field of study, as it relates to human health and environmental safety. Radiation-resistance mechanisms in extremophiles are a research hotspot, as this knowledge has great application value in bioremediation and development of anti-radiation drugs. Mount Everest, an extreme environment of high radiation exposure, harbors many bacterial strains resistant to radiation. However, owing to the difficulties in studying them because of the extreme terrain, many remain unexplored. In this study, a novel species (herein, S7-12^T) was isolated from the moraine of Mount Everest, and its morphology and functional and genomic characteristics were analyzed. The strain S7-12^T is white in color, smooth and rounded, non-spore-forming, and non-motile and can survive at a UV intensity of 1000 J/m², showing that it is twice as resistant to radiation as Deinococcus radiodurans. Radiation-resistance genes, including IbpA and those from the rec and CspA gene families, were identified. The polyphasic taxonomic approach revealed that the strain S7-12^T (=KCTC 59114T =GDMCC 1.3458T) is a new species of the genus Knoellia and is thus proposed to be named glaciei. The in-depth study of the genome of strain S7-12^T will enable us to gain further insights into its potential use in radiation resistance. Understanding how microorganisms resist radiation damage could reveal potential biomarkers and therapeutic targets, leading to the discovery of potent anti-radiation compounds, thereby improving human resistance to the threat of radiation. Full article