Extracellular Enzymes Research Articles

Bioavailability of dissolved organic matter (DOM) derived from seaweed Gracilaria lemaneiformis meditated by microorganisms

Seaweed Gracilaria lemaneiformis, a significant oceanic primary producer, releases substantial dissolved organic matter (DOM) during growth and decay, potentially impacting coastal organic carbon reservoirs and microbial communities. This study aimed to investigate the bioavailability of Gracilaria-derived DOM and its interactions with microbial communities. Laboratory experiments introduced Gracilaria-derived DOM into natural seawater, tracking variations in DOM composition, microbial structure, and eight extracellular enzyme activities over 168 h. The results indicated a rapid breakdown of dissolved organic carbon, nitrogen, and phosphorus, representing 48 % to 90 % of their total concentrations within 168 h, highlighting the high DOM bioavailability. Tryptophan substances were identified as the primary components of Gracilaria-derived DOM, being highly labile and utilized by microorganisms. Within the initial 0–12 h of DOM influx, Proteobacteria significantly increased and dominated in bacterial community, while after 48 h, as DOM decomposed, Desulfobacterota became the dominant group. The labile DOM stimulated bacteria, particularly Proteobacteria, to release substantial extracellular enzymes that peaked within the first 12 h. Subsequent substrate depletion led to decreased enzyme activities. Positive correlations were observed among bacterial abundance, enzyme activities, and tryptophan substances, emphasizing the intricate interplay among microbial communities, labile DOM, and extracellular enzymes. This study underscores the high bioavailability of Gracilaria-derived DOM and its interactions with microbial communities in nearshore environments.

Assessment of Phytochemical Compounds, Enzyme Production, and Antifungal, Antioxidant, and Anti-mutagenic Activities in Endophytic Fungi Derived from Mangrove Trees

Mangrove forest is a unique wetland ecosystem that is highly productive and provides an environment for a variety of microorganisms. Endophytic fungi derived from mangrove plants provide the plants with protection from adverse environmental conditions, while also allowing the fungi to produce valuable bioactive compounds. The present study sampled 11 mangrove trees and isolated, screened, and identified the potent endophytic fungi and their bioactive substances showing anti-pathogenic, anti-mutagenic and antioxidant activities, while the endophytes were investigated for their enzymatic potential. In total, 47 endophytic fungi were isolated from the leaves (36) and stems (11) of the host plants and all isolates were tested for antagonistic activities against selected plant pathogens. Based on the results, isolates BgS-04 and BcL-05 had the highest anti-pathogenic activities against Curvularia sp., Fusarium sp., and Colletotrichum sp. Therefore, the ethyl acetate crude extracts from these two fungi were further investigated for their antioxidant and anti-mutagenic activities and their phenolic compound contents, based on phytochemical analysis. Based on the results, the crude extracts of BgS-04 and BcL-05 contained 5.24 and 4.8 mg gallic acid equivalent/g of total phenolic compounds, respectively, and had antioxidant activity (half maximal inhibitory concentration) levels of 7.4 and 4.26 mg/mL, respectively. The preliminary qualitative phytochemical analysis of the fungal crude extracts identified tannins and coumarins. The anti-mutagenic activity levels of BgS-04 and BcL-05 against the mutagenic compounds, Trp-P-1 and DMBA, were determined using the Ames test, which revealed that the crude extracts of BgS-04 and BcL-05 had moderate-to-high antimutagenic potential against TA98 and TA100.All 47 endophytic isolates were assessed for their potential role in producing extracellular enzyme; they were capable of producing protease (53%), pectinase (28%), amylase (26%) and cellulase (19%) but none of them produced lipase. Among the isolates, RmL-01 derived from the leaves of Rhizophora mucronata had the significantly highest amylase production. Maximum amylase production (141.2 U/mL) was observed at 30 °C, pH 7.0 and 120 hours of incubation time. Molecular identification of the isolates BgS-04, BcL-05 and RmL-01 using nuclear ribosomal DNA internal transcribed spacer sequences revealed that they were Pestalotiopsis parva, Collectotrichum perseae, and Aspergillus oryzae, respectively, with high bootstrap support. It was concluded that the distinct groups of mangrove endophytes were potential sources of novel and valuable bio-based compounds with impressive anti-plant pathogen, anti-mutagenic, and antioxidant activities and capable of producing multi-industrial enzyme cocktails that might be important and useful for biotechnological applications.

Abstract IA027: Age-related stromal changes drive breast cancer tumor progression

Abstract Age is the single largest risk factor for the development of cancer, but how age impacts the molecular mechanisms that drive cancer remain poorly understood. While it is clear that age-related accumulation of cell autonomous mutations contributes to tumorigenesis, the central role age-related changes in the tumor microenvironment play in the transformation process is becoming more fully appreciated. Underscoring the importance of an aged microenvironment in cancer development are findings that senescent fibroblasts, which accumulate with age, directly stimulate preneoplastic and neoplastic cell growth and tumor progression. Investigations into how senescent fibroblasts promote tumorigenesis revealed that they express a plethora of growth factors, extracellular matrix remodeling enzymes, chemokines, and cytokines collectively referred to as the senescence associated secretory phenotype (SASP). Chemotherapy induces similar changes that can negatively impact a patient’s quality of life. We will discuss how these changes impact tumor progression and therapy-induced bone loss. Citation Format: Sheila A. Stewart. Age-related stromal changes drive breast cancer tumor progression [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr IA027.

In Situ Galacto-Oligosaccharides Synthesis in Whey Powder Fortified Milk by a Modified β-Galactosidase and Its Effect on the Techno-Functional Characteristics of Yogurt.

In situ galacto-oligosaccharide (GOS) synthesis in milk using β-galactosidases is an effective method for developing prebiotic dairy products. However, the low lactose concentration in milk (∼4.6%, w/w) reduces the GOS yield. In this study, a modified β-galactosidase from Bacillus circulans (mBgaD-D) with enhanced transglycosylation activity at low lactose concentration was developed through directed evolution and saturation mutagenesis. The GOS yield by mBgaD-D increased from 22.8% (wild type) to 30.8% in 50 g/L lactose (phosphate buffer). Pmgut was a strong sorbitol-inducible promoter from Bacillus subtilis. The expression of mBgaD-D in B. subtilis, coupled with the Pmgut promoter, resulted in a 6.4-fold increase (compared to the P43 promoter) in extracellular enzyme activity. Additionally, adding whey powder to boost the initial lactose concentration further improved the GOS yield, which reached 43% under the optimized conditions. Combining mBgaD-D and whey powder enhanced milk sweetness, producing no sugar-added, GOS-enriched yogurt (GOSY). The GOS content in GOSY was 4.1/100 g, providing an appropriate level of sweetness and yielding a yogurt that is elastic as well as firm. GOSY also increased the population of Bifidobacterium spp. during a 24 h in vitro fecal fermentation. Thus, fortifying yogurt with mBgaD-D and whey powder can enhance its technological properties and health benefits.

Enhancing Manganese Peroxidase: Innovations in Genetic Modification, Screening Processes, and Sustainable Agricultural Applications.

Manganese peroxidase (MnP), a vital extracellular enzyme for the degradation of lignin and other organic pollutants, has demonstrated immense potential for agricultural and environmental applications, including straw pretreatment, feed fermentation, mycotoxin degradation, and water treatment. However, current research remains in its exploratory phase, with naturally sourced MnP unable to meet industrial-scale demands and no mature commercial enzyme preparations available on the market. This comprehensive review innovatively constructs a framework for MnP research, probing into its molecular conformation and catalytic principles, while providing an overview of the advancements in high-throughput screening and In silco designing strategies. Specifically, this review focuses on the practical applications of MnP in sustainable agriculture, elaborating on its potential and challenges in straw resource utilization, efficient feed fermentation, mycotoxin control, and water quality improvement. Furthermore, this review summarizes the recent achievements in optimizing MnP activity through enzyme engineering techniques and discuss customized mutation strategies tailored to specific agricultural and environmental requirements, thereby laying a solid theoretical foundation and scientific basis for the industrial production and commercialization of MnP.

Exploration of Pseudomonas knackmussii AD02 for the biological mitigation of post-harvest aflatoxin contamination: Characterization and degradation mechanism

Aflatoxins, known for their potent carcinogenic and mutagenic properties, pose a major threat to human and animal health. Due to the impacts of climate change, aflatoxin contamination has emerged as a critical food safety issue, necessitating the development of effective detoxification strategies to mitigate its severe health risks. The current isolated, identified, and characterized bacterial strains from peanut-growing soils that are capable of degrading aflatoxin B1 (AFB1). Coumarin was used as a selective carbon source during isolation. Bacterial isolate AD02 had the highest AFB1 degradation efficiency (88.85%). Morphological and genetic analyses confirmed AD02 as a Gram-negative, rod-shaped bacterium closely related to Pseudomonas knackmussii. Optimization studies using a Box-Behnken design showed that initial pH significantly affected AFB1 degradation, with the optimal conditions identified as pH 7, 25 °C, and 24 h of incubation, resulting in approximately 90% AFB1 degradation. Additionally, P. knackmussii AD02 simultaneously degraded a mixture of AFB1, AFB2, AFG1, and AFG2. A mechanistic study of AFB1 degradation revealed the role of extracellular enzymes, particularly in proteinaceous and membrane-associated components. The mechanism for AFB1 degradation involved the hydrolytic cleavage of the lactone ring in the coumarin moiety, followed by the cleavage of the cyclopentenone ring and the elimination of double bonds in the furan and coumarin moieties. The in silico predictions indicated that this bacterium could metabolize AFB1 into a non-mutagenic and non-carcinogenic intermediate product. This study represents the first report on aflatoxin degradation by P. knackmussii, highlighting its potential as an effective biological agent for aflatoxin detoxification.

Microbial Life in Playa-Lake Sediments: Adapted Structure, Plastic Function to Extreme Water Activity Variations

Saline shallow lakes in arid and semi-arid regions frequently undergo drying episodes, leading to significant variations in salinity and water availability. Research on the impacts of salinity and drought on the structure and function of biofilms in hypersaline shallow lakes is limited. This study aimed to understand the potential changes of biofilms in playa-lake sediments during the drying process. Sediments were sampled at different depths (surface, subsurface) and hydrological periods (wet, retraction, and dry), which included a decrease in water activity (aw, the availability of water for microbial use) from 0.99 to 0.72. aw reduction caused a greater effect on functional variables compared to structural variables, indicating the high resistance of the studied biofilms to changes in salinity and water availability. Respiration and hydrolytic extracellular enzyme activities exhibited higher values under high aw, while phenol oxidase activity and prokaryote biomass increased at lower aw. This shift occurred at both depths but was more pronounced at the surface, possibly due to the more extreme conditions (up to 0.7 aw). The increased levels of extracellular polymeric substances and carotenoids developed at low aw may help protect microorganisms in high salinity and drought environments. However, these harsh conditions may interfere with the activity of hydrolytic enzymes and their producers, while promoting the growth of resistant prokaryotes and their capacity to obtain C and N sources from recalcitrant compounds. The resilience of biofilms in hypersaline lakes under extreme conditions is given by their resistant biochemichal structure and the adaptability of their microbial functioning.

Characterization and Selection of Potential Starters of Bacillus Sp. Involved in the Fermentation of Néré Seeds (Parkia biglobosa) in Côte d'Ivoire

Aims: The present study highlights about Bacillus sp. starter strains to control fermentation of Parkia biglobosa (néré) seeds. Place and Duration of Study: Between February and August 2023, this work was performed at Laboratory of Biochemistry, Microbiology and Valorization of Agroresources, of the Agropastoral Management Institute, which is part of Peleforo Gon Coulibaly University (Korhogo, Côte d'ivoire). Methodology: Fermented néré seeds were collected from soumbara producers in the Korhogo region in northern Côte d'Ivoire. Néré seeds were subjected to a physicochemical analysis to determine the pH, titrable acidity, moisture, dry matter and ash content. These fermented seeds were used for the isolation and enumeration of Bacillus bacteria. Production of extracellular enzymes and the influence of stress conditions were carried out on these strains to select potential starters. Results: The study of the physicochemical analysis of fermented néré seeds showed that these seeds have a pH of 6.59 ± 0.04, close to neutrality, with a very low titrable acidity of 0.06 ± 0.00%. The moisture content of the néré seeds is 38.76 ± 0.13% with a high dry matter content of 61.24 ± 0.22% coupled with a low ash content of 3.18 ± 0.05%. Thirty-three (33) Gram-positive bacilli were isolated from néré seeds with a microbial load of 7.1 log10 cfu/g. The production of extracellular enzymes and the influence of stress conditions led to the selection of five Bacillus strains (BS 08, BS 14, BS 19, BS 22 and BS 31) as potential starters. Conclusion: The control of the fermentation of néré seeds involves selecting strains with the best potential. Thus, five Bacillus sp. Isolates (BS 08, BS 14, BS 19, BS 22 and BS 31) were selected as potential starters for obtaining a soumbara of exceptional nutritional and organoleptic quality.

Extracellular Enzymes of Soils Under Organic and Conventional Cropping Systems: Predicted Functional Potential and Actual Activity

Conventional cropping systems (CCSs) rely heavily on large-scale and intensive crop production, using mechanical tillage and synthetic inputs such as chemical fertilizers and pesticides. While these methods can be economically beneficial, they can also be environmentally destructive. Organic cropping systems (OCSs), on the other hand, offer a more sustainable approach with less harmful effects on the environment. CCSs exhibit higher prevalence rates compared to OCSs. This means that there is less research on soil processes in organic fields and the impact of these processes on soil quality. In this study, we aim to assess the functional potential of soils by analyzing their ability to transform carbon, nitrogen, phosphorus, and sulfur. We use shotgun sequencing data to predict the activities of enzymes involved in these cycles. These predictions are then compared to the actual enzyme activity measured in the soil. The objects of study are samples of Chernozem soil from fields cultivated for 11 years using the OCS method and 20 years using the CCS method. It was found that the chemical properties of the studied soils differed significantly in terms of total carbon and total and available nitrogen and phosphorus. Except for phosphorus, the concentration of these elements was significantly higher in the CCS than in the OCS. We assessed the quality of the soils by measuring their enzymatic activities. A comparison of the two cropping systems showed that the activities of the enzymes involved in the C, N, P, and S cycles were, on average, 2.91, 1.89, 1.74, and 1.86 times higher in the CCS than in the OCS, respectively. A two-way PERMANOVA showed that the cropping system was the main variable (F = 14.978, p < 0.01) determining the enzymatic activity of soils, followed by soil depth (F = 9.6079, p < 0.01). We used shotgun sequencing to identify functional genes involved in C, N, P, and S metabolism, as well as genes encoding the measured soil enzymes. Compared to the OCS, the CCS soils had a higher relative abundance of genes involved in N-conversion (log2(FC) +0.22), C-conversion (log2(FC) +0.14), P-conversion (log2(FC) +0.47), and S-conversion (log2(FC) +0.24). At the same time, we found no significant differences between the systems in the relative abundance of genes encoding the measured soil enzymes. Thus, the comparison of the two cropping systems studied showed that the soil microbiome in the CCS has a greater functional potential to support biogeochemical cycles of the key biogenic elements than in the OCS. In addition, this study links the data on the representation of functional genes with the actual activity of enzymes. Based on the results, it would be helpful to focus more specifically on actual enzyme activity or to combine several indicators to obtain a more accurate understanding of soil quality.

Spatio-temporal distribution and biotechnological potential of culturable yeasts in the intertidal sediments and seawater of Aoshan Bay, China.

Marine yeasts play a crucial role in marine microbial ecology, facilitating the biogeochemical cycling of carbon and nitrogen in marine ecosystems, while also serving as important reservoirs of bioactive compounds with extensive applications in pharmaceuticals, agriculture, and various industries. Intertidal flats, characterized by their complex ecological dynamics, are postulated to harbor a wealth of yeast resources. This study employed a culture-dependent approach to assess the diversity, spatio-temporal distribution, and biotechnological potential of yeast communities residing within the intertidal sediments and seawater of Aoshan Bay. A total of 392 yeast strains were identified from 20 distinct genera, encompassing 43 recognized species and four candidate novel species. Notably, 17 of these species were identified as novel occurrences in marine environments, underscoring the rich yeast biodiversity of the Aoshan Bay ecosystem, with Candida emerging as the dominant genus in both sedimentary and aqueous habitats. Yeast community composition exhibited significant spatial and temporal variation, with peak diversity and abundance observed in autumn, the subtidal zone, and the surface soil layer. No clear pattern, however, emerged linking these shifts to specific changes in community composition, highlighting the complex interactions between microbial communities, environmental variables, and anthropogenic disturbance. Although several yeast species isolated here have been previously recognized for their biotechnological potential, their diverse and abundant extracellular enzyme profiles were characterized, further highlighting their crucial role in organic matter decomposition and nutrient cycling within the tidal ecosystem, as well as their potential applicability in the food, fine chemical, textile, and pharmaceutical industries.IMPORTANCEThis study presents groundbreaking insights into the yeast diversity of Aoshan Bay, offering invaluable information on their spatial and temporal distribution patterns, as well as their biotechnological potential in the tidal environment. The findings reveal that the eutrophic intertidal flat is a rich repository of yeasts with abundant extracellular enzymatic activity and an important role in nutrient cycling and decomposition processes. Also, these yeasts serve as crucial indicators of ecosystem health and function and are excellent candidates for biotechnological and industrial applications. Collectively, this study not only expands our knowledge of the diversity and distribution of intertidal yeasts but also highlights their promising potential for biotechnological applications.

Fungal Extracellular Enzymes from Aspergillus spp. as Promising Candidates for Extra-Heavy Oil Degradation and Enhanced Oil Recovery

Fungal Extracellular Enzymes from Aspergillus spp. as Promising Candidates for Extra-Heavy Oil Degradation and Enhanced Oil Recovery

Revealing the metabolic potential and environmental adaptation of nematophagous fungus, Purpureocillium lilacinum, derived from hadal sediment

The extreme environment shapes fungi in deep-sea sediments with novel metabolic capabilities. The ubiquity of fungi in deep-sea habitats supports their significant roles in these ecosystems. However, there is limited research on the metabolic activities and adaptive mechanisms of filamentous fungi in deep-sea ecosystems. In this study, we investigated the biological activities, including antibacterial, antitumor and nematicidal activity of Purpureocillium lilacinum FDZ8Y1, isolated from sediments of the Mariana Trench. A key feature of P. lilacinum FDZ8Y1 was its tolerance to high hydrostatic pressure (HHP), up to 110 MPa. We showed that HHP affected its vegetative growth, development, and production of secondary metabolites, indicating the potential for discovering novel natural products from hadal fungi. Whole-genome sequencing of P. lilacinum FDZ8Y1 revealed the metabolic potential of this piezotolerant fungus in carbon (carbohydrate metabolism), nitrogen (assimilatory nitrate reduction and protein degradation) and sulfur cycling processes (assimilatory sulfate reduction). Transcriptomic analysis under elevated HHP showed that P. lilacinum FDZ8Y1 may activate several metabolic pathways and stress proteins to cope with HHP, including fatty acid metabolism, the antioxidant defense system, the biosynthetic pathway for secondary metabolites, extracellular enzymes and membrane transporters. This study provides valuable insights into the metabolic potential and adaptation mechanisms of hadal fungi to the challenging conditions of the hadal environment.

ERO1A levels are a prognostic indicator in EGFR mutated non small cell lung cancer

We have identified endoplasmic reticulum oxidoreductase 1 alpha (ERO1A) as a poor prognostic indicator in epidermal growth factor receptor (EGFR)-mutated non-small cell lung cancer (EGFRMUT-NSCLC). In addition, comparison of high versus low ERO1A expression among cohorts of EGFRMUT-NSCLC primary samples revealed that ERO1A expression correlated with increased expression of proteins that regulate secretion. Using the CPTAC proteomic data set in lung adenocarcinoma we found that high ERO1A protein expression correlated with both extracellular matrix and matrix modifying enzymes. In this report, we found that ablating ERO1A expression was a determinant of clonogenicity, tumor sphere formation, spheroid growth and growth in vivo, as well as response to Osimertinib. We validated that ERO1A-knockout EGFRMUT-LUAD cell lines demonstrated a reduction in secretion of both laminin gamma 2 (LAMC2) and the collagen modifying enzyme lysyl oxidase-like 2 (LOXL2). Our work supports the role of ERO1A in modulating the tumor microenvironment that is likely to contribute to tumor progression.

Illuminating bioprocess responses to metal-based nanoparticles addition along hydrogen and methane production pathways: A review.

Recent research has discussed the positive impacts of metal-based nanoparticles (NPs) on bioprocesses producing either hydrogen (H2) or methane (CH4). The enhancement has been explained by mechanisms such as direct interspecies electron transfer (DIET), metal corrosion, and dissimilatory reduction. Such interactions could induce further benefits, such as controlling oxidation-reduction potential (ORP), mitigating toxicants, promoting enzymatic activity, and altering the microbiome, which have not yet been comprehensively discussed. Factors like metal type, oxidation state, and size of NPs are crucial for their reactivity and corresponding responses. This review discusses how different redox potentials of metals can regulate metabolic pathways and how NPs and their reactive ions can eliminate toxicants (e.g., sulfate) and enhance the activity of intra- and extracellular enzymes. The enrichment of responsive microorganisms in correlation with NPs is further discussed. A better understanding of the multifaceted role of metal-based NPs can guide potential new incorporation strategies to improve bioprocesses.

Endoplasmic Reticulum Oxidative Stress Promotes Glutathione-Dependent Oxidation of Collagen-1A1 and Promotes Lung Fibroblast Activation.

Changes in the oxidative (redox) environment accompany idiopathic pulmonary fibrosis (IPF). S-glutathionylation of reactive protein cysteines is a post-translational event that transduces oxidant signals into biological responses. We recently demonstrated that increases in S-glutathionylation promote pulmonary fibrosis, which was mitigated by the deglutathionylating enzyme glutaredoxin (GLRX). However, the protein targets of S-glutathionylation that promote fibrogenesis remain unknown. In the present study we addressed whether the extracellular matrix is a target for S-glutathionylation. We discovered increases in COL1A1 (collagen 1A1) S-glutathionylation (COL1A1-SSG) in lung tissues from subjects with IPF compared with control subjects in association with increases in ERO1A (endoplasmic reticulum [ER] oxidoreductin 1) and enhanced oxidation of ER-localized PRDX4 (peroxiredoxin 4), reflecting an increased oxidative environment of the ER. Human lung fibroblasts exposed to TGFB1 (transforming growth factor-β1) show increased secretion of COL1A1-SSG. Pharmacologic inhibition of ERO1A diminished the oxidation of PRDX4, attenuated COL1A1-SSG and total COL1A1 concentrations, and dampened fibroblast activation. Absence of Glrx enhanced COL1A1-SSG and overall COL1A1 secretion and promoted the activation of mechanosensing pathways. Remarkably, COL1A1-SSG resulted in marked resistance to collagenase degradation. Compared with COL1, lung fibroblasts plated on COL1-SSG proliferated more rapidly and increased the expression of genes encoding extracellular matrix crosslinking enzymes and genes linked to mechanosensing pathways. Overall, these findings suggest that glutathione-dependent oxidation of COL1A1 occurs in settings of IPF in association with enhanced ER oxidative stress and may promote fibrotic remodeling because of increased resistance to collagenase-mediated degradation and fibroblast activation.

Plant community composition and traits modulate the impacts of drought intensity on soil microbial community composition and function

Terrestrial ecosystems are increasingly threatened by extreme drought events. Soil microbial communities are central to terrestrial ecosystem function via their role in regulating biogeochemical cycling. Consequently, the impact of increasingly intense drought events on soil microbial communities will have knock-on effects for how ecosystems cope with climate change. In an outdoor grassland mesocosm experiment, we determined how increasing drought intensity affects bacterial and fungal community composition, and functioning, during and after drought. We also tested whether plant community resource acquisition strategy (fast- versus slow-strategy plant communities), plant community composition, and plant functional traits mediate soil microbial responses to increasing drought intensity. We found that increasing drought intensity markedly shifted bacterial and fungal community composition, and these effects persisted until the end of the experiment (two months after re-wetting). Bacterial and fungal communities that experienced severe droughts did not return to baseline composition, while those that experienced a mild drought did. Microbial community functioning (potential extracellular enzyme activity) was reduced at peak drought and shortly after re-wetting. While drought intensity effects on bacterial or fungal communities were insensitive to plant community resource acquisition strategy, functional group abundance (aboveground biomass of grass or forb plant species) composition (grass:forb ratio) and leaf traits (leaf dry matter content and leaf nitrogen concentration) explained significant variation in bacterial and fungal community composition during and after drought. Notably, plant community leaf dry matter content and soil nitrogen were the key factors mediating the effect of increasing drought intensity on microbial indicator taxa (ASVs). We conclude that increasing drought intensity affects grassland soil microbial communities during and after drought, and this impact is influenced by plant community composition and functional traits.

Effects of inorganic nitrogen enrichment on soil CH4 and CO2 production in freshwater and mesohaline marshes across six estuaries in China

Eutrophication is an important environmental stressor in coastal wetlands that alters ecosystem processes including primary production and the carbon cycle. However, how different nitrogen eutrophication scenarios may affect CH4 and CO2 production along a salinity gradient in coastal wetlands is poorly known. We collected the surface soil samples from both tidal freshwater and mesohaline Phragmites australis marshes in six main estuaries in China and conducted inorganic nitrogen enrichment anaerobic incubation experiments. Background soil CH4 and CO2 production rates were strongly correlated with total nitrogen but not salinity. On average, nitrate enrichment decreased soil CH4 and CO2 production rates by ca. 20 % in freshwater marsh and 16–43 % in mesohaline marshes, whereas ammonium enrichment decreased CO2 production by ca. 26–30 % but had no effect on CH4 production. Salinity was not an important mitigating factor in either eutrophication scenario. In most cases, nitrogen addition decreased the extracellular enzyme activities of β-1,4-glucosidase and cellobiohydrolase, but increased the activity of β-N-acetyl glucosaminidase, phenol oxidase and peroxidase. Nitrate addition decreased the mcrA gene abundance on average by 34–35 % but ammonium addition had insignificant effect. Total nitrogen availability was an important driver of CH4 and CO2 production rates in these tidally influenced coastal wetlands. Our results showed that tidal marshes with salinity < 15 ppt had similar soil CH4 production rates, and increasing inorganic nitrogen eutrophication might lower soil microbial carbon gas production in both tidal freshwater and mesohaline marshes.

6-Paradol exhibits antimicrobial, anti-quorum sensing and anti-virulence capacities on gram-negative bacteria: In vitro and in vivo studies

Grains of paradise, which are native to Africa, contain 6-paradol, an antibacterial compound found in plants of the Zingiberaceae family. In this study, the antimicrobial and anti-virulence properties of 6-paradol were evaluated against significant Gram-negative bacteria. The assessment encompassed the impact of 6-paradol on the bacterial cell membrane, efflux mechanisms, bacterial motility, biofilm formation, and extracellular enzyme production. The findings demonstrated promising anti-quorum sensing activity of 6-paradol. Moreover, the outcomes unveiled that the antimicrobial activity of 6-paradol is primarily stems from its substantial influence on the bacterial cell membrane and efflux mechanisms. Furthermore, 6-paradol exhibited potential anti-virulence activities by effectively reducing the generation of biofilm and virulent enzymes, impeding bacterial motility, and inhibiting in vivo bacterial pathogenesis. These anti-virulence effects were attributed to the compound's interference with quorum sensing systems and the downregulation of genes associated with these systems. Additionally, when combined with antibiotics, 6-paradol demonstrated synergistic effects. In conclusion, 6-paradol possesses noteworthy anti-virulence activities and can be employed as an auxiliary alongside antibiotics for treating aggressive Gram-negative infections. This highlights its potential as a valuable addition to therapeutic strategies.

Fungal and enzymatic pretreatments of bamboo lignocellulose towards high-strength biocomposites: Biological macromolecule/enzyme interaction and bonding enhancement

An energy-intensive and chemical-consuming pretreatment of bamboo is often required to develop its high-performance composites. This study is to evaluate a fungal and enzymatic pretreatment as a sustainable surface modification approach towards high-strength bamboo biocomposites based on D. sinicus. Extracellular enzyme activity analysis suggested that the lignin oxidative enzyme and pectinase secreted by the white-rot fungus T. versicolor achieved higher reaction than the hydrolytic enzymes throughout the pretreatment. Chemical structure analysis revealed that lignin and hemicellulose were partially depolymerised and/or removed during the pretreatment, leading to a relatively higher cellulose content in D. sinicus. The analysis of physical property and microstructure suggested that the surface wettability and porosity of pretreated D. sinicus were significantly improved, facilitating the spreading and penetration of adhesive resins, which subsequently contributed to the superior interfacial bonding of the biocomposites. The tensile strength of the biocomposites increased from 195.8 MPa to 245.8 MPa and the bonding strength increased from 4.9 MPa to 6.3 MPa after the pretreatment, which were 1.26 times and 1.28 times those of the untreated biocomposite respectively. The results proved that the fungal and enzymatic pretreatment is a promising, eco-friendly and efficient surface modification approach for the preparation of high-strength lignocellulosic biocomposites.

Effects of Acupuncture on Cartilage Degradation and Joint Pain in Osteoarthritis

Osteoarthritis, resulting from joint decline, leads to various symptoms including joint pain, stiffness, tenderness, and local inflammation. These symptoms may be caused by the remodeling of the five structural phenotypes: inflammatory, subchondral bone, meniscal cartilage, atrophic, and hypertrophic phenotypes. Studies have shown that acupuncture can inhibit cartilage degradation by regulating extracellular matrix-degradation and enzyme synthesis. Notably, the efficacy of acupuncture treatment in osteoarthritis may be attributed to regulated inflammation and apoptosis of chondrocytes, as well as endogenous opioid production, and activation of the endocannabinoid systems (in the central and peripheral nervous systems), to contribute towards cartilage protection and joint pain relief. This review provides a current summary of the mechanisms of action of acupuncture in osteoarthritis, indicating that acupuncture, a therapy with fewer side effects than conventional medications, may be an effective treatment strategy for the management of osteoarthritis.