Cell Wall Research Articles

Evolutionary trajectories of β-lactam resistance in Enterococcus faecalis strains

ABSTRACT Resistance to ampicillin and imipenem in Enterococcus faecalis is infrequent. However, the evolution of resistance can occur through prolonged antibiotic exposure during the treatment of chronic infections. In this study, we conducted a long-term evolution experiment using four genetically diverse strains of E. faecalis with varying susceptibilities to ampicillin and imipenem. Each strain was subjected to increasing concentrations of either ampicillin or imipenem over 200 days, with three independent replicates for each strain. Selective pressure from imipenem led to the rapid selection of highly resistant lineages across all genetic backgrounds, compared to ampicillin. In addition to high resistance, we describe, for the first time, the evolution of a β-lactam-dependent phenotype observed in lineages from all backgrounds. Whole-genome sequencing and bioinformatic analysis revealed mutations in three main functional classes: genes involved in cell wall synthesis and degradation, genes in the walK/R two-component system, and genes in the c-di-AMP pathway. Our analysis identified new mutations in genes known to be involved in resistance as well as novel genes potentially associated with resistance. Furthermore, the newly described β-lactam-dependent phenotype was correlated with the inactivation of c-di-AMP degradation, resulting in high levels of this second messenger. Together, these data highlight the diverse genetic mechanisms underlying resistance to ampicillin and imipenem in E. faecalis . The emergence of high resistance levels and β-lactam dependency underscores the importance of understanding evolutionary dynamics in the development of antibiotic resistance. IMPORTANCE Enterococcus faecalis is a major human pathogen, and treatment is frequently compromised by poor response to first-line antibiotics such as ampicillin. Understanding the factors that play a role in susceptibility/resistance to these drugs will help guide the development of much-needed treatments.

Phase Diagrams for Anticlastic and Synclastic Bending Curvatures of Hexagonal and Re-entrant Honeycombs

Abstract Transformation between saddle- and dome-like bending shapes of regular and re-entrant hexagonal honeycomb panels are explored. An analytical model is proposed to uncover the underlying mechanisms and identify the controlling parameter when the cell walls are slender beams. Then, 3D finite element simulations are performed to examine the architecture dependence of bending shape and construct the phase diagrams of anticlastic and synclastic curvatures when the cell walls have a general geometry. The results are believed helpful to the design and application of related honeycomb structures.

Biosorption of cypermethrin from aqueous solutions by Pediococcus acidilactici: kinetics, isotherms, and mechanisms

AbstractBACKGROUNDPediococcus acidilactici is an effective adsorbent for removing of pyrethroid insecticides. This study investigated the biosorption characteristics and mechanisms of P. acidilactici D15 using adsorption measurement, scanning electron microscopy, and Fourier‐transform infrared spectroscopy. Isotherm and kinetic models were used to analyze the biosorption process.RESULTSThe Langmuir isotherm model best described the cypermethrin biosorption process, with the maximum adsorption capacity of P. acidilactici D15 being 21.404 mg/g. The biosorption appeared to involve monolayer coverage with uniform forces. The pseudo‐second‐order model also fits well. The rate‐controlling steps involved intraparticle diffusion, film diffusion and chemosorption. The main cellular components involved in cypermethrin biosorption were exopolysaccharides, spheroplast, and cell wall, especially peptidoglycan. The functional groups (–OH, –NH, –CH3, –CH2, –CH, –CONH–, –CO, and –C–O–C–) from proteins, polysaccharides, and peptidoglycan on the cell surface likely played a role in binding cypermethrin. Additionally, P. acidilactici D15 effectively reduced cypermethrin in pickle wastewater.CONCLUSIONThese findings suggest that P. acidilactici D15 could be a potential agent for reducing pesticide residues, laying the groundwork for treating pickle wastewater containing such pesticide residues. © 2024 Society of Chemical Industry.

LiaR-dependent gene expression contributes to antimicrobial responses in group A Streptococcus

ABSTRACT The ability to sense and respond to host defenses is essential for pathogen survival. Some mechanisms involve two-component systems (TCSs) that respond to host molecules, such as antimicrobial peptides (AMPs), and activate specific gene regulatory pathways to aid in survival. Alongside TCSs, bacteria coordinate cell division proteins, chaperones, cell wall sortases, and secretory translocons at discrete locations within the cytoplasmic membrane, referred to as functional membrane microdomains (FMMs). In group A Streptococcus (GAS), the FMM or “ExPortal” coordinates protein secretion, cell wall synthesis, and sensing of AMP-mediated cell envelope stress via the LiaFSR three-component system. Previously, we showed that GAS exposure to a subset of AMPs (α-defensins) activates the LiaFSR system by disrupting LiaF and LiaS co-localization in the ExPortal, leading to increased LiaR phosphorylation, expression of the transcriptional regulator SpxA2, and altered GAS virulence gene expression. The mechanisms by which LiaFSR integrates cell envelope stress with responses to AMP activity and virulence are not fully elucidated. Here, we show the LiaFSR regulon is comprised of genes encoding SpxA2 and three membrane-associated proteins: a PspC domain-containing protein (PCP), the lipoteichoic acid-modifying protein LafB, and the membrane protein insertase YidC2. Our data support that phosphorylated LiaR induces transcription of these genes via a conserved operator, whose disruption attenuates GAS virulence and increases susceptibility to AMPs in a manner primarily dependent on differential expression of SpxA2. Our work expands our understanding of the LiaFSR regulatory network in GAS and identifies targets for further investigation of mechanisms of cell envelope stress tolerance contributing to GAS pathogenesis.

Synthesis and Fungicidal Activity Evaluation of Novel Triazole Thione/Thioether Derivatives Containing a Pyridylpyrazole Moiety

Compounds containing N‐pyridylpyrazole motif have aroused interest and brought about research hotspots due to their highly‐efficient insecticidal activity. The fungicidal potential of N‐pyridylpyrazole derivatives has gradually been disclosed in recent years. To discover new agrochemicals with poly‐heterocyclic features, a series of novel triazole thione/thioether derivatives containing pyridylpyrazole motif (8‐11) was synthesized. The new compounds were identified by melting point, 1H NMR, 13C NMR, 19F NMR, HRMS, and elemental analysis. The bioassays showed that most of the pyridylpyrazole‐containing triazole thione Mannich bases possessed favorable in vitro fungicidal activity toward pathogenic fungi, such as Magnaporthe oryzae, Sclerotinia sclerotiorum, Botrytis cinerea and Fusarium verticillioides, and were comparable with those of the contrast compounds A and triadimefon. Some of them exhibited moderate to good in vivo fungicidal activity against S. sclerotiorum at 0.2 mg/mL (e.g. 8f control efficacy: 60.9±3.2%). The SEM observation displayed that 8f might cause disruption of cell membrane and wall of S. sclerotiorum. Compounds 8a, 8c, 8f‐8h, 8p and 9b can serve as promising new fungicidal agents to make further structural optimization. The findings in this article provide useful clue and guidance for the design and development of new poly‐heterocyclic agrochemicals.

Nano-fertilizers: The future of nutrient approaches for cereals

Nanotechnology offers a promising solution to address the nutrient demands of cereals, which are nutrient-intensive crops typically reliant on large amounts of inorganic fertilizers. These large quantities of nutrients are supplied to the crop by applying a huge amount of inorganic fertilizer as a soil application led to a decline in environmental systems, particularly affecting the soil health, lesser use efficiency of fertilizers and water resources contamination. In this context, nanotechnology serves as a potential solution. The huge demand for nutrients in cereal crops is met by nano-fertilizers. The nano-fertilizers are now playing a promising role in fulfilling the nutrient requirement of the crops by replacing the normal conventional fertilizers not only for cereals but also for other agricultural crops. The mechanism of action of nano-fertilizers is that they are smaller than the pore size of plant cell walls, allowing them to easily enter and reach the plasma membrane. Nano-fertilizers have 100 times greater surface area than conventional fertilizers, allowing them to easily interact with plant surfaces and increase the absorption of nutrients. Therefore, the nutrient-use efficiency of the crop is increased and shown a positive effect on the physiological and growth parameters of cereal crops, resulting in enhanced yield and improved drought tolerance. This review discussed, the effects and efficiency of nano-fertilizers on cereal crop growth and the correlation between physiological, qualitative, quantitative traits with nano-form of application in detailed manner. This review concludes that nano-fertilizers are the potential nutrient source for cereal crops like rice (Oryza sativa L.), wheat (Triticum aestivum L.), maize (Zea mays) etc. and they are going to be a promising resource for nutrient management in agricultural crops.

Arenicolide Family Macrolides Provide a New Therapeutic Lead Combating Multidrug‐Resistant Tuberculosis

AbstractThe emergence of multidrug‐resistant (MDR) and extensively drug‐resistant (XDR) strains of Mycobacterium tuberculosis (Mtb) poses a significant threat to health globally. During searching for new chemical entities regulating MDR‐ and XDR‐Mtb, chemical investigation of the black oil beetle gut bacterium Micromonospora sp. GR10 led to the discovery of eight new members of arenicolides along with the identification of arenicolide A (Ar−A, 1), which was a previously reported macrolide with incomplete configuration. Genomic analysis of the bacterial strain GR10 revealed their putative biosynthetic pathway. Quantum mechanics‐based computation, chemical derivatizations, and bioinformatic analysis established the absolute stereochemistry of Ar−A and arenicolides D−K (Ar−D−K, 2–9) completely for the first time. Biological studies of 1–9 revealed their antimicrobial activity against MDR and XDR strains of Mtb. Ar−A had the most potent in vitro antimicrobial efficacy against MDR‐ and XDR‐Mtb. Mechanistically, Ar−A induced ATP depletion and destabilized Mtb cell wall, thereby inhibiting growth. Notably, Ar−A exerted a significant antimicrobial effect against Mtb in macrophages, was effective in the treatment of Mtb infections, and showed a synergistic effect with amikacin (AMK) in a mouse model of MDR‐Mtb lung infection. Collectively, our findings indicate Ar−A to be a promising drug lead for drug‐resistant tuberculosis.

Single-cell transcriptomics unveils skin cell specific antifungal immune responses and IL-1Ra- IL-1R immune evasion strategies of emerging fungal pathogen Candida auris

Candida auris is an emerging multidrug-resistant fungal pathogen that preferentially colonizes and persists in skin tissue, yet the host immune factors that regulate the skin colonization of C. auris in vivo are unknown. In this study, we employed unbiased single-cell transcriptomics of murine skin infected with C. auris to understand the cell type-specific immune response to C. auris. C. auris skin infection results in the accumulation of immune cells such as neutrophils, inflammatory monocytes, macrophages, dendritic cells, T cells, and NK cells at the site of infection. We identified fibroblasts as a major non-immune cell accumulated in the C. auris infected skin tissue. The comprehensive single-cell profiling revealed the transcriptomic signatures in cytokines, chemokines, host receptors (TLRs, C-type lectin receptors, NOD receptors), antimicrobial peptides, and immune signaling pathways in individual immune and non-immune cells during C. auris skin infection. Our analysis revealed that C. auris infection upregulates the expression of the IL-1RN gene (encoding IL-1R antagonist protein) in different cell types. We found IL-1Ra produced by macrophages during C. auris skin infection decreases the killing activity of neutrophils. Furthermore, C. auris uses a unique cell wall mannan outer layer to evade IL-1R-signaling mediated host defense. Collectively, our single-cell RNA seq profiling identified the transcriptomic signatures in immune and non-immune cells during C. auris skin infection. Our results demonstrate the IL-1Ra and IL-1R-mediated immune evasion mechanisms employed by C. auris to persist in the skin. These results enhance our understanding of host defense and immune evasion mechanisms during C. auris skin infection and identify potential targets for novel antifungal therapeutics.

Arenicolide Family Macrolides Provide a New Therapeutic Lead Combating Multidrug-Resistant Tuberculosis.

The emergence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains of Mycobacterium tuberculosis (Mtb) poses a significant threat to health globally. During searching for new chemical entities regulating MDR- and XDR-Mtb, chemical investigation of the black oil beetle gut bacterium Micromonospora sp. GR10 led to the discovery of eight new members of arenicolides along with the identification of arenicolide A (Ar-A, 1), which was a previously reported macrolide with incomplete configuration. Genomic analysis of the bacterial strain GR10 revealed their putative biosynthetic pathway. Quantum mechanics-based computation, chemical derivatizations, and bioinformatic analysis established the absolute stereochemistry of Ar-A and arenicolides D-K (Ar-D-K, 2-9) completely for the first time. Biological studies of 1-9 revealed their antimicrobial activity against MDR and XDR strains of Mtb. Ar-A had the most potent in vitro antimicrobial efficacy against MDR- and XDR-Mtb. Mechanistically, Ar-A induced ATP depletion and destabilized Mtb cell wall, thereby inhibiting growth. Notably, Ar-A exerted a significant antimicrobial effect against Mtb in macrophages, was effective in the treatment of Mtb infections, and showed a synergistic effect with amikacin (AMK) in a mouse model of MDR-Mtb lung infection. Collectively, our findings indicate Ar-A to be a promising drug lead for drug-resistant tuberculosis.

The FERONIA–RESPONSIVE TO DESSICATION 26 module regulates vascular immunity to Ralstonia solanacearum

Abstract Some pathogens colonize plant leaves, but others invade the roots, including the vasculature, causing severe disease symptoms. Plant innate immunity has been extensively studied in leaf pathosystems; however, the precise regulation of immunity against vascular pathogens remains largely unexplored. We previously demonstrated that loss of function of the receptor kinase FERONIA (FER) increases plant resistance to the typical vascular bacterial pathogen Ralstonia solanacearum. Here, we show that upon infection with R. solanacearum, root xylem cell walls in Arabidopsis thaliana become highly lignified. FER is specifically upregulated in the root xylem in response to R. solanacearum infection, and inhibits lignin biosynthesis and resistance to this pathogen. We determined that FER interacts with and phosphorylates the transcription factor RESPONSIVE TO DESICCATION 26 (RD26), leading to its degradation. Overexpression and knockout of RD26 demonstrated that it positively regulates plant resistance to R. solanacearum by directly activating the expression of lignin-related genes. Tissue-specific expression of RD26 in the root xylem confirmed its role in vascular immunity. We confirmed that the FER–RD26 module regulates lignin biosynthesis and resistance against R. solanacearum in tomato (Solanum lycopersicum). Taken together, our findings unveil that the FER–RD26 cascade governs plant immunity against R. solanacearum in vascular tissues by regulating lignin deposition. This cascade may represent a key defense mechanism against vascular pathogens in plants.

Indole-3-acetic acid treatment promotes postharvest kiwifruit softening by regulating starch and cell wall metabolism

The softening process of postharvest kiwifruit is a critical aspect of fruit quality that has been extensively studied. However, the impact of indole-3-acetic acid (IAA) treatment on this process remains largely unexplored. In this study, we examined the effect of IAA treatment on the softening of postharvest kiwifruit. The results depicted that kiwifruit treated with IAA exhibited decreased firmness and increased ethylene production. Treatment with IAA upregulated the expression of starch decomposition genes, including AcSEX and AcBAM, resulting in a reduction in starch content. Additionally, IAA treatment induced cell wall breakdown, attributed to the enhanced transcript levels of cell wall-related degradation genes such as AcPE, AcPG, AcPL, and AcCX compared to the control. Consequently, IAA-treated kiwifruit displayed lower levels of cellulose and protopectin but higher levels of water-soluble pectin. In summary, our findings indicate that exogenous IAA promoted postharvest starch and cell wall biodegradation in kiwifruit, which reduced fruit firmness and accelerated fruit softening.

Description of Olsenella absiana sp. nov., an anaerobic bacterium isolated from pig faeces

A short-rod-shaped, obligate anaerobic, Gram-positive bacterium isolated from the faeces of a pig was designated as the strain YH-ols2223T. Analysis of the 16S rRNA gene sequence revealed that the isolate was most closely related to Olsenella urininfantis KCTC 25755T with 97.7% similarity. The multi-locus sequence tree revealed that the isolate formed a sub-cluster within the genus Olsenella. The average nucleotide identity and the digital DNA–DNA hybridization values for the isolate and the most closely related strains were 74.9–76.6% and 20.8–22.5%, respectively. The end products of the fermentation were lactic acid and acetic acid. The main fatty acids identified were C18 : 0 DMA, C18 : 1 ω9c DMA and C18 : 1 ω9c. The cell wall contained the meso-diaminopimelic acid-based peptidoglycan. Given the chemotaxonomic, phenotypic and phylogenetic properties, YH-ols2223T (= KCTC 25800T = NBRC 116680T) represents a novel taxon. The name Olsenella absiana sp. nov. was proposed.

Gen-AI Methods, Molecular Docking and Molecular Dynamics Simulations for Identification of Novel Inhibitors of MmPL3 Transporter of Mycobacterium tuberculosis

Mycobacterium tuberculosis (Mtb), the bacterium responsible for tuberculosis (TB), employs mycolic acids to build its cell wall. This robust structure plays a vital role in protecting the bacterium from external threats and contributes to its resistance against antibiotics. Mycobacterial membrane protein Large 3 (MmpL3), a secondary resistance nodulation division transporter, is essential in mycolic acid biosynthesis, transporting mycolic acid precursors into the periplasm using the proton motive force. Due to its role in bacterial cell wall formation, it is a promising target for new tuberculosis treatments. In this study, starting with 85 known MmPL3 compounds, the artificial intelligence (AI)-assisted tool “Design of Druglike Analogues (DeLA-Drug)” was employed to generate about 15,000 novel molecules. These compounds were then subjected to structure-based high-throughput virtual screening and molecular dynamics (MD) simulations to identify potential novel inhibitors of MmpL3. The binding affinity was obtained by docking the above molecules at the SQ109 binding site in MmPL3, followed by pharmacokinetics and toxicity, which were used to reduce the chemical space. Finally, five ligands were subjected to 100 ns MD simulations to investigate the binding energetics of inhibitors to MmpL3. These compounds demonstrated stable binding and favorable drug-like properties, indicating that they could serve as potential novel inhibitors of MmpL3 for Mtb.

Inositol pyrophosphate catabolism by three families of phosphatases regulates plant growth and development

Inositol pyrophosphates (PP-InsPs) are nutrient messengers whose cellular levels are precisely regulated. Diphosphoinositol pentakisphosphate kinases (PPIP5Ks) generate the active signaling molecule 1,5-InsP8. PPIP5Ks harbor phosphatase domains that hydrolyze PP-InsPs. Plant and Fungi Atypical Dual Specificity Phosphatases (PFA-DSPs) and NUDIX phosphatases (NUDTs) are also involved in PP-InsP degradation. Here, we analyze the relative contributions of the three different phosphatase families to plant PP-InsP catabolism. We report the biochemical characterization of inositol pyrophosphate phosphatases from Arabidopsis and Marchantia polymorpha. Overexpression of different PFA-DSP and NUDT enzymes affects PP-InsP levels and leads to stunted growth phenotypes in Arabidopsis. nudt17/18/21 knock-out mutants have altered PP-InsP pools and gene expression patterns, but no apparent growth defects. In contrast, Marchantia polymorpha Mppfa-dsp1ge, Mpnudt1ge and Mpvip1ge mutants display severe growth and developmental phenotypes and associated changes in cellular PP-InsP levels. Analysis of Mppfa-dsp1geand Mpvip1ge mutants supports a role for PP-InsPs in Marchantia phosphate signaling, and additional functions in nitrate homeostasis and cell wall biogenesis. Simultaneous elimination of two phosphatase activities enhanced the observed growth phenotypes. Taken together, PPIP5K, PFA-DSP and NUDT inositol pyrophosphate phosphatases regulate growth and development by collectively shaping plant PP-InsP pools.

Pectinesterase activity and gene expression correlate with pathogenesis of Phytophthora infestans

Late blight caused by Phytophthora infestans is the most devastating disease of potato. Phytophthora infestans produces many secondary metabolites and effector proteins, involved in the pathogenesis, which compromise host defense mechanisms. Pectinesterase (PE) is a cell wall degrading enzyme secreted by P. infestans to infect the host. To examine the role of PE in P. infestans, 15 strains of P. infestans were isolated from infected potato leaves in Yunnan, China. We analyzed the biological effects of exogenously added PE on P. infestans and its activity and gene expression after infection of potato using quantitative real-time polymerase chain reaction (RT-PCR). It was found that PE significantly promotes the growth of P. infestans, increases the weight of mycelium and the number of sporangia, and promotes the sporangial germination. PE accelerated the infection process of P. infestans on potato. The pathogenicity of P. infestans was positively correlated with PE activity and gene expression. PE is a key to the virulence difference of potato late blight.

Melatonin Priming Regulates Mineral Uptake, Osmolite Accumulation, and Cell Wall Structure in Buckwheat Under Cadmium Stress

Melatonin Priming Regulates Mineral Uptake, Osmolite Accumulation, and Cell Wall Structure in Buckwheat Under Cadmium Stress

Relationship between submergence of graft union and auxin accumulation of grafted mango trees under flooded conditions

ABSTRACT In recent years, many fields have been affected by floods. In mango trees, grafted trees are more susceptible to flood damage than seedling trees, When the graft union is submerged. In this study, the translocation of substances, especially auxin, through the graft union was investigated to clarify the causes of death in mango trees when the trunk was submerged up to the graft union. After approximately 1 month of flooding, changes were observed in root respiration, carbon dioxide release from the trunk, and leaf stomatal conductance. The auxin content in the scion increased significantly from 19.5 ng g−1 dry weight (DW) in the control to 122.1 ng g−1 (DW) in the flooded treatment. Nevertheless, no significant increase in auxin content was observed in the rootstock. In addition, there was no pectin degradation, leading to the death of the grafted mango trees. Auxin accumulation induces expansins, which are cell wall proteins that loosen the cell wall structure and are involved in structural changes in cell wall polysaccharides. Therefore, submergence of the graft union may inhibit auxin translocation between the scion and rootstock, resulting in pectin degradation in the scion bark and leading to tissue breakdown and death of the mango tree.

Converging Roles of the Metal Transporter SMF11 and the Ferric Reductase FRE1 in Iron Homeostasis of Candida albicans

ABSTRACTPathogenic fungi must appropriately sense the host availability of essential metals such as Fe. In Candida albicans and other yeasts, sensing of Fe involves mitochondrial Fe‐S clusters. Yeast mutants for Fe‐S cluster assembly sense Fe limitation even when Fe is abundant and hyperaccumulate Fe. We observe this same disrupted Fe sensing with C. albicans mutants of SMF11, a NRAMP transporter of divalent metals. Mutants of smf11 hyperaccumulate both Mn and Fe and the elevated Mn is secondary to Fe overload. As with Fe‐S biogenesis mutants, smf11∆/∆ mutants show upregulation of ferric reductases that are normally repressed under high Fe, and Fe import is activated. However, unlike Fe‐S biogenesis mutants, smf11∆/∆ mutants show no defects in mitochondrial Fe‐S enzymes. Intriguingly, this exact condition of disrupted Fe sensing without inhibiting Fe‐S clusters occurs with C. albicans fre1∆/∆ mutants encoding a ferric reductase. Mutants of fre1 and smf11 display similar perturbations in the cell wall, in filamentation and in the ROS burst of morphogenesis, a Fe‐dependent process. As with FRE1, SMF11 is important for virulence in a mouse model for disseminated candidiasis. We propose a model in which FRE1 and SMF11 operate outside the mitochondrial Fe‐S pathway to donate ferrous Fe for Fe sensing.

Ginger Essential Oil Exerts Antibacterial Activity Against Shewanella putrefaciens by Disrupting Cell Structure and Resisting Biofilm

ABSTRACTThis study aimed to elucidate the antibacterial mechanism and antibiofilm activity of ginger essential oil (GEO) against Shewanella putrefaciens. On the basis of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), alkaline phosphatase (AKPase), succinate dehydrogenase (SDH), and glucose‐6‐phosphate dehydrogenase (G6PDH) activities were analyzed to evaluate the damage degree of S. putrefaciens on cell wall and membrane, and the microstructure was observed by scanning electron microscope (SEM) to evaluate the action effect against S. putrefaciens. The results showed that the MIC and MBC of GEO against S. putrefaciens were 27.8125 mg/mL and 55.625 mg/mL, respectively. The surface structures and cell membrane of S. putrefaciens were rigorously damaged by 1 MIC and 2 MIC GEO, leading to the leakage of cellular nucleic acids, protein, and β‐galactosidases from the bacterial cells. GEO could not only decrease the biomass of biofilm but also remove mature biofilm. In addition, GEO could reduce the production of exopolysaccharides and extracellular proteins, and could lessen the metabolic activity of biofilm cells. These results demonstrated that GEO exhibited efficient antibacterial characteristics against S. putrefaciens, which could act as a natural antibacterial and antibiofilm agent on the preservation of aquatic products.

Pressure-tolerant survival mechanism of Schizophyllum commune 20R-7-F01 isolated from deep sediments 2 kilometers below the seafloor

In anaerobic high hydrostatic pressure (HHP) sedimentary environments below the seafloor, fungi are found to dominate the eukaryotic communities, playing crucial ecological roles. However, the specific mechanisms by which fungi adapt to anaerobic HHP environments remain unclear. In this study, we investigated Schizophyllum commune 20R-7-F01 isolated from coal-bearing sediments at a depth of 2 km below the seafloor. By assessing the cell viability, biomass, and cell wall thickness changes of strain 20-7-1 under different HHP conditions, we observed that, compared to 0.1 MPa, strain 20-7-1 exhibited slower growth rates and decreased cell viability at 15 MPa and 35 MPa, yet demonstrated significant pressure tolerance. Transcriptomic and metabolomic analyses revealed that this strain activated the carbohydrate metabolic process to simultaneously utilize ethanol and lactic acid fermentation pathway. Additionally, it activates the oxidoreductase activity and hydrolase activity pathways to detoxify intracellular reactive oxygen species (ROS). Activation of the metal ion binding pathway increases the proportion of unsaturated fatty acids in the cell membrane, while instigation of the integral component of membrane pathway maintains cell wall structural stability. Furthermore, activation of the DNA repair pathway repairs DNA damage, demonstrating its comprehensive adaptive mechanisms against the HHP stress. These research findings deepen our understanding of fungal survival strategies and adaptation mechanisms in extreme environments, laying the groundwork for further exploration of their roles in cycling of carbon, nitrogen, sulfur, and other elements in the deep biosphere.