Abstract Malassezia furfur is fungi associated with various diseases; however, the mechanisms underlying its pathogenicity and the relationship between probiotics and fungi remain largely unknown. In the present study, Caenorhabditis elegans was used as the model host to evaluate M. furfur pathogenicity. Additionally, effects of lactic acid bacteria against M. furfur pathogenicity were evaluated. Compared to Escherichia coli OP50 (OP, control), both live and heat-killed M. furfur reduced the lifespan and body size of C. elegans, although heat-killed M. furfur was less effective than live M. furfur in lifespan shortening. Furthermore, unlike heat-killed M. furfur, live M. furfur disrupted the nematode intestinal barrier. Loss-of-function mutants of nsy-1 and sek-1, which encode components of the MAPK signaling pathway, were susceptible to M. furfur, suggesting their involvement in the defense against M. furfur infection. Expression of genes involved in host defense and of those coding for C-type lectin domain-containing proteins and antimicrobial peptides was upregulated in M. furfur-infected C. elegans. Lacticaseibacillus rhamnosus (LR) significantly ameliorated lifespan shortening and body size reduction in M. furfur-infected C. elegans and protected against intestinal barrier disruption, suggesting that LR protects nematodes from M. furfur virulence. This study highlights M. furfur pathogenicity and intestinal barrier disruptive ability in C. elegans and suggests that the M. furfur virulence is partially attenuated by LR.
Abstract Despite their ecological importance and protected status, the diversity, host associations, and evolutionary relationships of coccidia infecting shrews (Eulipotyphla: Soricidae) remain poorly understood. In particular, the extent of host specificity, the occurrence of host-switching events, and the relationships among coccidian lineages infecting different shrew hosts remain unclear. Here, we investigated coccidian diversity and phylogenetic relationships across several shrew genera and species to clarify parasite-host associations and provide new insights into the evolutionary processes shaping coccidian diversity in shrews. Faecal samples from 188 shrews representing the genera Crocidura, Neomys, Sorex, and Suncus, collected across multiple localities in Europe and two localities in Asia, were examined. Coccidia were detected in one quarter of the samples, generally at low intensities. Phylogenetic analyses based on partial COX1, COX3, and 18S rRNA sequences identified four distinct clusters: three were host-specific (two associated with Crocidura and one with Neomys), whereas one lineage was shared among Crocidura, Neomys, and Sorex. Two Isospora sequences from Sorex araneus clustered with isosporans previously reported from moles. No clear geographic structuring was observed, and the phylogenetic structure also did not mirror the observed morphological characters. The results indicate that host switching and subsequent repeated dispersal occur in eimerians of shrews, suggesting that these processes may be more widespread across small-mammal hosts than previously recognized. The findings expand current knowledge on coccidian diversity in shrews and provide new insights into the host specificity, ecology, and evolutionary dynamics of the parasitic protists.
Acute respiratory infections caused by influenza A/B (Flu A/Flu B), respiratory syncytial virus (RSV), and adenovirus (ADV) remain a major global health burden. The COVID-19 pandemic profoundly altered respiratory virus transmission through nonpharmaceutical interventions (NPIs). Samples from patients with respiratory tract infections at Hangzhou Hospital of Traditional Chinese Medicine from January 2020 to October 2024 were collected. ADV, Flu A, Flu B, and RSV were detected to evaluate the impact of NPIs on viral epidemiology. Statistical analyses were performed using SPSS software and GraphPad Prism. Multivariable binary logistic regression models, adjusting for age group and sex, were constructed to evaluate the independent effect of NPI relaxation (strict NPI period 2020-2022 vs. post-relaxation period 2023-2024) on virus positivity. Stratified analyses by age group and demographic comparability assessments between periods were also performed. Overall virus positivity declined from 27.4% (2020) to 14.5% (2021) during strict NPIs, then rebounded to 35.1% in 2023 after relaxation. Flu A resurged atypically in summer 2022 and dominated the 2023 winter peak, while Flu B increased annually and peaked in 2024. ADV regained its prepandemic summer seasonality by 2024, whereas RSV showed limited seasonal variation. Higher ADV positivity was observed in males, and higher Flu B positivity in females. By 2024, influenza burden shifted toward adults and geriatric populations, while children under five remained most vulnerable to RSV and ADV. However, after adjusting for demographic shifts-including a significant increase in adult patients (18-60 years: 22.1%-40.0%) and altered sex ratios between periods (both P < 0.001)-the post-relaxation period showed lower adjusted odds of positivity for all four pathogens (Flu A: aOR = 0.64, 95% CI: 0.61-0.67; Flu B: aOR = 0.67, 95% CI: 0.63-0.70; ADV: aOR = 0.72, 95% CI: 0.68-0.76; RSV: aOR = 0.62, 95% CI: 0.59-0.65; all P < 0.001), whereas no significant sex differences were observed after multivariable adjustment (all P > 0.05). Stratified analyses further revealed that the magnitude of period-related risk reduction increased with age for all pathogens. This study demonstrates that the postpandemic resurgence of respiratory viruses in Hangzhou, Zhejiang Province, was not a monolithic recrudescence following NPIs relaxation, but a multifaceted shifting epidemiology driven by three convergent forces: expanded school-based and community screening that broadened the tested denominator, demographic case-mix shifts toward higher-risk adult populations, and pathogen-specific alterations in seasonal and age-specific transmission patterns. The consistently lower adjusted odds of positivity during the post-relaxation period indicate that crude resurgence signals must be interpreted through the lens of surveillance structure. This study demonstrates that the postpandemic resurgence of respiratory viruses in Hangzhou (2020-2024) was not a uniform transmission rebound following NPI relaxation, but a shifting epidemiology shaped by surveillance structural changes, pathogen-specific resilience, and altered population immunity. Multivariable models showed lower adjusted odds after restriction easing, while age-stratified analyses revealed heterogeneous period effects superimposed on stable risk hierarchies. In this subtropical Chinese city, influenza reasserted prepandemic seasonality, whereas RSV and ADV exhibited delayed recovery. These insights advocate for adaptive, age-targeted public health strategies-prioritizing adult vaccination for influenza and sustained pediatric prevention for RSV and ADV-that account for both biological transmission dynamics and surveillance artifacts in the post-COVID-19 era.
Abstract Infectious mononucleosis is clinically difficult to distinguish from bacterial causes of tonsillitis/pharyngitis. First-line investigations include monospot testing, despite 63% sensitivity in certain cohorts. Therefore, national recommendations include repeating an initial negative monospot within five to seven days. A point-of-care clinical scoring tool could improve clinical outcomes, increase diagnostic accuracy and reduce unnecessary testing. We conducted a retrospective cohort study at Luton and Dunstable University Hospital including patients aged 15-24 presenting with sore throat, lymphadenopathy or fever between 01/01/2021-31/01/2024 who underwent monospot testing. Extracted data included demographics, observations, and laboratory results. Patients were randomly split into training (80%) and testing (20%) cohorts. Eleven parameters were used to develop four predictive models; classical multivariate logistic regression, machine-learning logistic regression with LIBLINEAR approximation, machine-learning decision tree classifier, and a simplified clinical risk-stratification model from machine-learning methods. 278 presentations from 264 patients were included. The machine-learning decision tree classifier demonstrated superior performance, achieving 100% sensitivity, 98.0% specificity and 98.2% diagnostic accuracy using only three parameters: lymphocyte count, neutrophil count and alanine aminotransferase. The simplified clinical risk-stratification model demonstrated 83.3% sensitivity, 98.0% specificity and overall 96.4% accuracy. All four models represent potential methods for developing clinical tools to predict monospot positivity. Our risk-stratification model showed significant promise as an easily memorisable, point-of-care clinical scoring tool. Using this, we propose an alternative diagnostic pathway with early counselling and de-escalation of antibiotics in high-risk cases, and reduced testing in low-risk cases; reducing population-level morbidity and epidemiological spread, whilst improving diagnostic accuracy and conserving resources.
Extremophiles are used to study both the limits of life and its potential elsewhere. Categories are commonly employed to describe extreme conditions, however, changing the focus to the underlying chemical alterations of cellular biomolecules permits a clearer delineation of the limits of life. This also provides a common basis for interdisciplinary studies of life in extreme environments intersecting biology, chemistry, geology, environmental and planetary sciences. Using this perspective, four general principles can be drawn from the past decades of research into extremophiles: 1-Microbial survival after exposure to environmental stressors is challenged by damage incurred at the molecular level, 2-Damage-susceptibility of cellular (macro)molecules vary by structure, chemical composition, and surrounding molecules, 3-Local physicochemical states alter the chemistry underpinning microbial survival, and 4-The same macromolecular chemical and/or structural damages produced by different stressors can be resisted by the same cellular mechanisms. These general principles provide a common basis for interdisciplinary studies of the limits of life. This chemistry-focused approach has implications for defining the limits of life, paleoenvironment reconstruction, site selection for sampling, and choice of appropriate model systems for development of detection methods for microbial cells and extraction of molecules. This approach also contributes to the field of astrobiology, constraining the concept of habitability in the solar system and exoplanets. Descriptive terms are useful in science, but for extremophile microbiology and astrobiology, it is useful to recognize that life resists chemistry, not conditions.
In the next decades, space telescope missions will search for life evidence on exoplanets, focusing on robust biosignatures associated with oxygenic photosynthesis, including atmospheric oxygen accumulation and the Vegetation Red-Edge in surface reflectance spectra. Many habitable rocky exoplanets orbit M dwarf stars, whose spectral energy distribution may condition the rise and evolution of oxygenic photosynthesis. M dwarf stars emit predominantly far-red (700-750 nm) and near-infrared (750-1000 nm) light, and relatively little visible (400-700 nm) radiation, which on Earth predominantly drives photochemistry in most oxygenic phototrophs. Previous experiments proved some oxygenic phototrophs can photosynthesize under simulated M dwarf light but less efficiently than under solar radiation simulated in the range 365-780 nm. Indeed, tested organisms present photosynthetic apparatus evolved to harvest Sun's visible light, however, M dwarfs' irradiation might select adaptations optimized for harvesting far-red/near-infrared light. We measured sensitivities of a far-red/near-infrared-utilizing cyanobacterium, Acaryochloris marina sp. str. Moss Beach to simulated M dwarf spectrum and primeval anoxic, CO2-rich atmosphere. This strain constitutively presents a high content of chlorophyll d, with in vivo absorption peak at 710 nm. Its permanently red-shifted photosynthetic apparatus required no acclimation to the stellar spectrum, maintaining strong growth and oxygen production, higher than that registered under simulated solar light. Moreover, abundant chlorophyll d caused a shift in whole-cell reflectance: the red-edge was beyond 700 nm, resulting in a Chl d-near-infrared-edge. Overall, a potentially similar metabolism on exoplanets orbiting M dwarfs could successfully produce both a gaseous biosignature and a characteristic surface biosignature.
Enterococcus faecium has become a significant nosocomial and opportunistic pathogen, increasingly implicated in severe infections such as urinary tract infections, bacteraemia, and endocarditis. Due to acquired resistance to vancomycin and ampicillin and high intrinsic resistance to other antibiotics, E. faecium infections are often challenging to treat. However, relatively little is known about the molecular factors used by E. faecium during infection. Here, we employed desthiobiotin-ATP as an activity-based probe to investigate the activity profile of ATP-binding proteins in E. faecium upon growth in standard rich laboratory media and in response to host-derived cues. We present a chemoproteomic dataset containing 230 selectively enriched putative ATP-binding proteins. Thirty-one proteins were specifically activated in response to human colonic organoid extract, 19 in response to human serum including the ABC transporter, TcyA, and a sensor histidine kinase, ArlS. Our findings suggest that E. faecium adapts its metabolic and regulatory pathways in response to host-derived signals from human serum and organoid extract, which could be crucial for its survival and pathogenicity in various host tissues. Our study highlights the potential relevance of TcyA and ArlS, that have been implicated in virulence in other pathogens, for further functional characterization in E. faecium.
Microbial multidrug resistance is a major public health concern, underscoring the urgent need for new antimicrobial natural products. In this study, strain F11, identified as Bacillus halotolerans, was selected based on its strong antimicrobial activity and taxonomic identification. Whole-genome sequencing revealed a single circular chromosome of 4.15 Mb with a GC content of 43.82%, encoding 4122 predicted proteins. Pangenome analysis identified 17 unique genes. Genome mining predicted 10 biosynthetic gene clusters (BGCs), including a complete fengycin cluster. Comparative analyses using BiG-SCAPE/CORASON and clinker revealed evolutionary divergence within the fengycin BGCs, including those identified in B. halotolerans F11 and B. halotolerans HMB20199. This divergence was further supported by NRPS substrate specificity predictions, which revealed two amino acid variations at positions 6 and 8 in the predicted fengycin decapeptide of strain B. halotolerans F11 compared to the canonical sequence. In contrast, B. halotolerans HMB20199 exhibited a mosaic fengycin-iturin hybrid organization, characterized by an extended NRPS assembly line comprising 19 modules. Furthermore, untargeted metabolomic profiling of B. halotolerans F11 detected 9719 metabolites, of which 3453 were successfully annotated. Integration of genomic and metabolomic datasets enabled the correlation of two compounds-bacillaene and bacillibactin-with their corresponding BGCs. However, the lack of detection of fengycin, surfactin, and subtilosin A was attributable to methodological constraints. Collectively, these findings expand our understanding of B. halotolerans strains as promising genomic reservoirs of novel NRPS-derived lipopeptides and highlight Algerian Sahara soils as a valuable source of antimicrobial natural products.
Heat killing is commonly employed to kill microorganisms, including Cryptococcus neoformans (C. neoformans), particularly in immunological studies and vaccine development. To assess the reliability of existing methods, we systematically reviewed 50 publications and identified 23 distinct protocols differing in temperature, duration, suspension concentration, and sample volume. Using two virulent strains, H99 and B3501, we experimentally tested these conditions and found that only 9 protocols achieved complete (100%) killing, whereas 14 resulted in partial killing. Consistent with this, only 17 publications (34%) reported complete killing, and just 20 studies described plating suspensions for validation, raising concerns that incomplete killing may have gone undetected. Further analysis revealed that suspension volume and fungal concentration critically influenced outcomes. These findings highlight substantial variability and insufficient validation across reported protocols, which may undermine reproducibility and biosafety. Our study provides evidence-based guidance for selecting effective heat-killing conditions, thereby supporting safer and more reliable use of heat-killed C. neoformans in experimental research.
Considering the harsh surface conditions on Mars, terrestrial organisms that can survive and remain detectable after exposure to similar conditions provide invaluable models for guiding current and future search-for-life missions. To this end, we evaluated the extremophilic archaeon Acidianus manzaensis grown on ESA01-E Mars analog material as a model organism. We exposed cell-mineral mixtures to one month of desiccation and 2 weeks of Mars-like conditions in a Mars simulation chamber to evaluate the potential for cell survival after exposure to these conditions. In the search for reliable biomarkers in other planetary environments, such as Mars, molecules that are stable over geological timescales while preserving information indicative of their potential biological origin are crucial. Thiophene-bearing quinones fulfill these requirements, and thiophenes, which are their basic moieties, have been discovered on Mars. Therefore, we analysed the thiophene-bearing quinone composition of A. manzaensis using mass spectrometry-based metabolomics and discussed potential molecular alterations. Successful recultivation after 1 month of desiccation and 2 weeks of exposure to Mars-like conditions proved the durability of the organism and its capability for cell recovery after exposure to extreme conditions, paving the way for further investigation.
White filamentous microbial mats are complex benthic communities, typically structured by sulfur-oxidizing bacteria from the Beggiatoaceae family, yet their diversity and ecological responses in mangrove ecosystems remain poorly characterized. Here, we provide a high-resolution analysis of bacterial communities associated with white microbial mats in marine mangrove sediments of Guadeloupe using 16S rRNA metabarcoding. Bacterial community composition was compared across sites with different levels of anthropogenic impact (protected, natural, and urban). While overall diversity remained stable, richness differed significantly between conditions, and beta diversity analyses revealed clear compositional structuring along the disturbance gradient. A conserved core microbiome was identified across all sites, whereas rare taxa were detected exclusively in urban sites, including Ferrimicrobium, Thermonospora, Alcanivorax, and Serratia, which has been previously associated with human-induced environmental changes. In contrast, Prosthecochloris and Chlorobaculum were highly abundant in protected sites, whereas Sulfurovum and Sulfurimonas dominated urban environments. The relative abundance of Beggiatoaceae also varied across sites, suggesting sensitivity to anthropogenic disturbance. Despite these compositional shifts, measured physicochemical parameters did not significantly correlate with the community structure, suggesting that microbial mat organization is influenced by fine-scale or unmeasured environmental gradients. Together, these findings indicate that white microbial mats respond to anthropogenic disturbance primarily through taxonomic restructuring rather than loss of diversity, highlighting their potential as sensitive indicators of environmental change in mangrove ecosystems.
Pyrenean ice caves are the least studies cryogenic environments that preserve perennial ice. These caves host microbial communities adapted to extreme oligotrophy, low temperatures, and episodic water availability, making them valuable analogues for subsurface habitats on icy planetary bodies. This study investigated four ice caves in the Central Pyrenees (Devaux, Cotiella A294, Sarrios 1 and Somola SO-01) to (i) characterize bacterial and microeukaryotic assemblages, (ii) assess how ice origin, physicochemical gradients, and cave geology structure these communities, and (iii) evaluate their relevance as terrestrial analogs for cold oligotrophic ecosystems. Amplicon sequencing of 16S and 18S rRNA genes, combined with detailed chemical profiling, revealed marked cave-specific differences associated with pH, major ions, short-chain organics, and ice-formation processes. Liquid water samples contained distinct assemblages dominated by ultra-small Patesibacteria, whereas firn-derived and congelation ice hosted stratified or hydrologically entrained communities. Microeukaryotic diversity was highest in light-exposed ice from Cotiella A294 and lowest in Sarrios 1, where fungal taxa prevailed. Redundancy analyses identified acetate, nitrate, sulfate, pH, and trace metals as the environmental variables most strongly aligned with microbial gradients. These findings provide a data-driven characterization of microbial organization in Pyrenean ice caves and offer empirical baseline parameters to inform future studies of microbial persistence and biosignature formation in cold terrestrial and extraterrestrial environments.
Persistent Staphylococcus aureus infections treated with prolonged daptomycin (DAP) can select for DAP resistance (DAP-R), reinforcing the need for combination strategies that both improve killing and constrain resistance evolution. Prior work suggests the DAP+ceftaroline (CPT) combination can deliver synergistic killing, prevent emergence of DAP-R, and resensitize DAP-R subpopulations toward a DAP-susceptible (DAP-S) phenotype. Here, using a clinically derived, MSSA isogenic DAP-S (616)/DAP-R (703) strain pair, we evaluated DAP+CPT activity across in vitro assays, ex vivo models, and an in vivo experimental infective endocarditis (IE) model, and integrated ultra-deep targeted sequencing to link phenotypic responses to genomic adaptation. DAP+CPT produced enhanced killing of both strains in vitro and ex vivo, improved target-tissue clearance of the DAP-R strain in vivo, prevented emergence of DAP-R in the DAP-S parental strain in vitro and ex vivo, and resensitized the DAP-R strain toward a DAP-S phenotype ex vivo. Genomically, ultra-deep sequencing of resistance loci (thousands-fold coverage) identified fixed background divergence versus the N315 reference and revealed regimen-dependent selection in membrane-stress pathways, including a high-frequency mixed mprF subpopulation consistent with DAP-driven heterogeneity under monotherapy, contrasted by distinct locus-level changes under combination exposure. In addition, coverage profiling detected a large, combination-associated mobile-element/prophage gene-content event in the 703 background affecting an immune-evasion/β-hemolysin-converting region, highlighting that antibiotic pressure can couple resistance dynamics with pathogenesis-relevant genome remodeling. Together, these data show that DAP+CPT provides potent activity beyond synergistic killing-improving clearance while constraining or reshaping resistance evolution-and they define genomic signatures that help explain divergent evolutionary trajectories under DAP alone versus DAP+CPT.
Desert cyanobacteria of the Chroococcidiopsis genus, due to their remarkable desiccation and radiation tolerance, are considered model candidates in the field of astrobiology. For this reason, three strains, namely Chroococcidiopsis sp. CCMEE 029, 057, and 064 have been exposed in the dried state to space- and Mars-like conditions throughout laboratory simulations and real space exposure using the EXPOSE facility installed outside the International Space Station. However, how they can recover upon rehydration and repair the damage accumulated under extreme conditions on Earth and in space remains to be fully elucidated through omics-based investigations. Hence, comparative genomics of these three Chroococcidiopsis strains offered a powerful lens to explore the genetic components of their capability to persist under extreme conditions. The analysis of newly obtained gapless genome assemblies of the laboratory-maintained reference strains of CCMEE 029, 057, and 064 allowed the identification of conserved and non-shared genes involved in reactive oxygen species detoxification, desiccation tolerance, DNA protection, and repair. Moreover, a biosynthetic gene cluster for scytonemin production was identified in every strain, while strain CCMEE 057 also harbored the genes for the biosynthesis of a mycosporine-like amino-acid. Such insights are crucial for understanding the adaptation strategies employed by microorganisms to survive in dry, radiation-intense environments, offering clues about the potential for life beyond Earth.
Methane-arrested anaerobic digestion (AAD) is a waste management strategy that produces carboxylic acid precursors to industrial products (fuels, bio-based polymers, and pharmaceuticals) from organic wastes. A major challenge preventing application of AAD is highly variable product profiles resulting from an inability to control the microbial communities underlying waste decomposition and product biosynthesis. Over time, lactic acid bacteria (LAB) often dominate AAD bioreactors and overproduce shorter chain acids causing acidosis. Here an AAD bioreactor where caproic acid production increased from an average of 3.9 g/l to an average of 12.3 g/l when the feedstock was switched from manure and paperboard to food waste. Time series shotgun metagenomics is used to investigate how microbial dynamics drive performance shifts. The dominant LAB shifted from Lactobacillus amylovorus spp. to Lactiplantibacillus pentosus spp. following the feedstock switch, corresponding with increased diversity and relative abundance (26.2%) of Caproicibacter spp. (putative chain elongator). Additionally, L. amylovorus MAGs encoded biosynthesis genes to produce the bacteriocin helveticin often produced by LAB to target closely related species. Lactiplantibacillus pentosus MAG.84 encodes bacteriocin-degrading enzymes and helveticin resistance genes, suggesting putitive mechanisms for bacteriocin resistance. These results suggest that bacteriocins may be an underappreciated mechanism for shaping microbial community dynamics in AAD.
Iron-rich microbial mats at low-temperature sites in deep-sea hydrothermal environments make a significant contribution to element cycling, especially the iron cycle. From these mats collected at the MIR zone (Trans-Atlantic Geotraverse hydrothermal field, Mid-Atlantic Ridge), enrichment cultures were performed to isolate strains involved in iron metabolism. Two strains, affiliated to Vibrio diazotrophicus (HER2-O and HER2-R), were isolated from this environment and might be able to oxidize iron under autotrophic and anaerobic or microaerophilic conditions, in addition to grow under organoheterotrophic conditions. In particular, genomic analyses revealed the presence of a c4 -type cytochrome (cyc1) that could be involved in electron transfer in the Fe(II)-oxidation pathway and a complete inorganic carbon fixation pathway (reductive glycine pathway), arguing in favor of growth based on autotrophic metabolism, using iron as an energy source. Prophages were identified in both genomes. Caudoviricetes-type virus morphotypes were evidenced by direct observations during growth under organoheterotrophic conditions. Genes providing metabolic adaptations to deep-sea hydrothermal vent conditions were also identified and could confer an ecological advantage to these two novel strains to thrive and compete effectively in metal-rich deep-sea environments. Their unexpected abilities regarding their potential to oxidize Fe(II), in addition to their physiological capacities, may help to explain their presence in iron-rich microbial mats.
Exposure to natural or artificial ionizing radiation induces direct damage to intracellular macromolecules and promotes the formation of reactive oxygen species, which can further amplify cellular injury. Although many organisms tolerate high radiation doses, the basis of this resilience is not fully understood. A proposed determinant is the intracellular manganese-to-iron ratio (Mn/Fe-ratio), thought to reduce oxidative stress. To evaluate its relevance, Mn and Fe levels were measured in 19 archaeal, bacterial, and two eukaryotic yeast species and compared these values with their survivability after ionizing radiation exposure. There was no consistent relationship between Mn/Fe-ratios and radiation tolerance across this broad phylogenetic range. Integrating our results with prior studies suggests that while elevated Mn/Fe-ratios may contribute to exceptional resistance in certain specialized microorganisms, the ratio is not a reliable, universal predictor of survivability. These findings highlight the multifactorial nature of radiation tolerance and indicate that other processes (e.g. DNA repair mechanisms, antioxidant defenses, and metabolic adaptations) likely play central roles. By clarifying the limitations of Mn/Fe-ratio as a generalizable marker, this study provides a more nuanced understanding of the biochemical determinants of radiation resistance and informs future research into mechanisms of cellular resilience under extreme stress.
Traditional plant-based products provide nutritional benefits and support cultural heritage; however, their sale in urban informal markets raises potential food safety considerations. We characterized the microbiota of five traditional dried plant products (baobab, masau, nyii, dinawa, and lude) obtained from three informal markets in South Africa (n = 51 samples) using 16S rRNA gene sequencing and quantitative real-time PCR; bacterial isolates (n = 87) were further evaluated using selected phenotypic assays. Bacterial abundance and composition varied across products and vendors. Baobab exhibited the highest microbial richness (1460 ASVs) but relatively low bacterial loads (106 16S rRNA gene copies g-1), whereas dried leafy greens showed the lowest richness (470 ASVs) but the highest bacterial abundance (109 copies g-1). Across products, higher bacterial diversity correlated with genera such as Bifidobacterium and Prevotella, while higher bacterial abundance correlated with genera such as Salmonella, Vibrio, and Acinetobacter. Notably, health implications of detected taxa cannot be inferred from genus-level identification based on 16S rRNA gene sequencing. Phenotypic traits observed among selected isolates included growth in the presence of several antibiotics (particularly sulfadiazine and ampicillin), protease activity, and inhibition of indicator strains under laboratory conditions. Overall, traditional dried plant foods harbor diverse microbial communities shaped by plant characteristics and vendor-related practices, highlighting the importance of improved handling and drying practices.
Escherichia coli TisB/IstR1 is a type I toxin-antitoxin system. The TisB toxin targets the inner membrane and disrupts the proton motive force (PMF). Under normal growth conditions, tisB transcription is repressed by the LexA SOS repressor, and IstR1 blocks its translation. DNA damage lifts LexA repression, allowing tisB mRNA to overcome IstR1 inhibition and produce TisB. Although spontaneous tisB expression has been reported, its physiological significance remains unclear. We show that tisB is spontaneously induced and TisB is synthesized during the transition to stationary phase, coinciding with decreased LexA repression and a transient decline in istR1 promoter activity. Deletion of tisB does not affect exponential growth but delays entry into and exit from stationary phase, reduces fitness under nutrient limitation and alkaline pH, and impairs stringent response induction, intracellular pH homeostasis, and glycogen accumulation-phenotypes consistent with metabolic dysregulation. These findings indicate that low-level spontaneous TisB production modulates metabolism during the transition to stationary phase. By collapsing the PMF, TisB attenuates nutrient uptake and promotes early stringent-response-driven dormancy before nutrient exhaustion. Our results reveal a physiological role for TisB, positioning it as a metabolic rheostat that fine-tunes adaptation to environmental fluctuations.
The increasing oil exploration and transport activities in the Arctic amplify the risk of oil spills in ice-containing marine environments. Chemical dispersants, intended to promote oil biodegradation by breaking hydrocarbons into small droplets, are potential tools in cold marine oil spill mitigation; however, their fate and effectiveness within sea ice remain uncertain. This study examined the influence of dispersed crude oil and the chemical dispersant (FinasolOSR 51) on microbial community dynamics and hydrocarbon-degrading potential compared to clean ice during an 89-day sea-ice mesocosm experiment using shotgun metagenomics and metagenome-assembled genomes. Dispersant addition markedly reshaped microbial communities in both dispersed-oil and dispersant containing ice, causing similar shifts toward psychrophilic hydrocarbon degraders such as Oleispira, Bermanella, and Pseudoalteromonas. Although aliphatic hydrocarbon degradation genes were enriched, several dominant taxa exhibited limited hydrocarbon metabolic capacity yet possessed extensive stress-response traits. Oil hydrocarbon loss in ice remained modest despite the presence of degraders, likely due to the very low microbial abundance. These findings demonstrate that dispersants can strongly shape microbial communities in Arctic sea ice, without necessarily enhancing the biodegradation of oil hydrocarbons. This highlights the need for careful evaluation of dispersants as remediation tools in ice-containing Arctic marine environments.
