Oxidase Activity Research Articles

Disrupting Intracellular Homeostasis by Copper-Based Nanoinducer with Multiple Enzyme-Mimicking Activities to Induce Disulfidptosis-Enhanced Pyroptosis for Tumor Immunotherapy.

Given the crucial role of abnormal homeostasis in tumor cells for maintaining their growth, it may be more efficient with less effort to develop anti-tumor strategies that target multiple combined mechanisms by disrupting intracellular homeostasis. Here, a copper-based nanoinducer (CGBH NNs) with multiple enzyme-like activities is designed and constructed to induce disulfidptosis-enhanced pyroptosis through disrupting multiple intracellular homeostasis for effective tumor immunotherapy. Within the tumor microenvironment (TME), CGBH NNs can disrupt intracellular glucose homeostasis and inhibit NADPH production, leading to accumulation of cystine, which further blocked the substrate and key enzyme for synthesizing glutathione. Subsequently, through cascade catalytic reactions involving enzyme activities (glutathione peroxidase-like, glucose oxidase and peroxidase-like activities), CGBH NNs can produce massive reactive oxygen species(ROS) and further disrupt intracellular redox homeostasis, resulting in the disulfidptosis-enhanced pyroptosis. The tumor cells undergoing immunogenic pyroptosis can release various cytosolic contents and inflammatory factors, eliciting robust immune responses by facilitating immune cell infiltration, and reprogramming the immunosuppressive TME. After the combination with immune checkpoint blockade therapy, CGBH NNs can effectively suppress the tumor growth and prolong the survival time of tumor-bearing mice. This work presents a novel paradigm to trigger disulfidptosis-enhanced pyroptosis by destroying intracellular homeostasis for anti-tumor immunotherapy.

Sodium nitroprusside enhances vase life of Polianthes tuberosa cut flowers by inducing defence enzymes

ABSTRACT The effect of sodium nitroprusside (SNP) in inducing the activity of the defence system enzymes and their role in the vase life of two Polianthes tuberosa cultivars (‘Mahalati’ and ‘Dezfouli’) was investigated. SNP pulsing (150 μM for 0, 24 and 48 h) induced the activity of the antioxidant enzymes, superoxide dismutase (SOD) and peroxidase (POX) up to 6 and 3 days after application, respectively. Also, the activities of phenylalanine ammonia-lyase (PAL) and polyphenol oxidase (PPO) increased in SNP-treated plants until 3 and 6 days after application, respectively. The activity of these enzymes after 48 h pulsing was higher than 24 h pulsing. However, in most cases, there was no statistical difference between these two treatments. The chlorophyll degradation was reduced and the electrolyte leakage and malondialdehyde accumulation in the petals of the SNP-treated plants were limited. These responses increased the vase life and opening rate of the florets. The increased activity of PAL and PPO is probably due to improving antimicrobial activity in the stem and improved vase solution uptake by flowers up to 9 days after the treatments. SNP pulsing for 24 h was suggested for increasing the vase life and quality of P. tuberosa cut flowers.

Zinc Oxide Nanoparticles Treatment Maintains the Postharvest Quality of Litchi Fruit by Inducing Antioxidant Capacity

Pericarp browning and fruit decay severely reduce the postharvest quality of litchi. Improving the antioxidant capacity of the fruit is an effective way to solve these problems. In our study, the appropriate zinc oxide nanoparticles (ZnO NPs) treatment and its mechanism of action on the storability of litchi was investigated. Litchi fruit was soaked in a 100 mg·L−1 ZnO NPs suspension, water, and 500 mg·L−1 prochloraz for 2 min, respectively. The results showed that the ZnO NPs treatment delayed pericarp browning and decay in litchi fruit and was more effective than prochloraz treatment. The ZnO NPs-treated fruit showed significantly increased contents of total anthocyanin, total phenols, and activities of DPPH scavenging, superoxide dismutase, and glutathione peroxidase, as well as the lowest activities of polyphenol oxidase and laccase. ZnO NPs generated hydrogen peroxide and superoxide anion radicals, which were beneficial in slowing down the decay and inducing antioxidant capacity. However, these reactive oxygen species also consumed catalase, peroxidase, glutathione, and glutathione peroxidase. This means that litchi should be treated with an appropriate concentration of ZnO NPs. We concluded that treatment with a 100 mg·L−1 ZnO NPs suspension could induce antioxidant capacity, which is a promising and effective method to maintain the postharvest quality of litchi.

Flavobacterium capsici sp. nov., isolated from the rhizospheric soils of bell pepper (Capsicum annuum L.).

Two separate bacterial strains, PMTSA4T and PMR2A8, were isolated from the rhizospheric soils of bell pepper plants grown in a plant nursery. These strains are Gram-negative, non-motile and rod-shaped and grow in aerobic conditions. They exhibit a positive reaction for catalase activity but negative results for oxidase activity. Phylogenetic analysis of the 16S rRNA gene sequences revealed that the strains PMTSA4T and PMR2A8 are closely related to Flavobacterium piscinae ICH-30T (95.6%, respectively), Flavobacterium ahnfeltiae 10Alg 130T (95.5%) and Flavobacterium maris KMM 9535T (95.3%), aligning them within the genus Flavobacterium. Digital DNA-DNA hybridization (dDDH) values and average nucleotide identities (ANIs) of the whole-genome sequences for the two strains and related Flavobacterium species were significantly below the established thresholds for prokaryotic species delineation (<70% for dDDH and <95% for ANI). The observed values were as follows: Flavobacterium aquatile LMG 4008T (dDDH: 19.8% and ANI: 75.5%), F. piscinae ICH-30T (dDDH: 18.6% and ANI: 73.3%) and F. stagni WWJ 16T (dDDH: 18.5% and ANI: 72.0%). The strains have genome sizes of 3 068 185 bp and 3 068 330 bp, with a G+C content of 32.5 mol%. In phenotypic characterization, the new strains grew at 10-35 °C and tolerated up to 4% NaCl at pH 5-9 (optimum pH 8). The predominant cellular fatty acids were observed to be iso-C15:0, iso-C17:0 3-OH and iso-C15:0 3-OH. Menaquinone-6 was the predominant quinone. Considering the results from phenotypic, chemotaxonomic, phylogenetic and genomic analyses, it is proposed that the strains PMTSA4T and PMR2A8 represent a novel species within the genus Flavobacterium.

Impact of the key residues of 1-Deoxy-D-Xylulose-5-Phosphate synthase on its catalysis

1-Deoxy-D-xylulose-5-phosphate synthase (DXS) is the first rate-limiting enzyme in the 2-methyl-D-erythritol-4-phosphate (MEP) terpenoid biosynthetic pathway. To explore the active sites of the protein, we made a series of mutations to the key amino acid residues of Escherichia coli DXS including H49, R420, D427, and R478. The results show that several mutants including H49Q lose almost all their catalytic activity in DXP synthesis, but the double-point mutants H49QD427H and H49QD427 N recover 100 % activity of the wild type enzyme. The kinetic characterization displays that the affinity of the double-point mutants for pyruvate and D-glyceraldehyde-3-phosphate only slightly decreases. We also assessed impact of the mutation on the oxidative decarboxylation activity of all the mutants. Despite the fact that H49QD427H and H49QD427 N get back the full activity with regard to DXP synthesis, their oxidase activity remains unrestored. Furthermore, we assayed the acceptor substrate spectrum of the mutants and the results show that a large portion of them catalyzes ligation between pyruvate and nitrosobenzene to form N-phenyl-N-hydroxyacetamide, whereas R420D, R420F, and D427H exhibit activity in connection of pyruvate and benzaldehyde to afford phenylacetocarbinol (PAC), with the first two mutants yielding (S)-PAC (yields 21 %-25 %, ee values 71–75 %) while D427H furnishing (R)-PAC (yield 41 %, ee value 91 %), implying the key role of D427 for the acceptor substrate recognition and the stereoselectivity of the enzyme. It is worth noting that this is the first report of DXS mutants that can recognize benzaldehyde as an acceptor substrate and generate both enantiomers of PAC.

Cu-Albumin Artificial Enzymes with Peroxidase and Oxidase Activity for Stereoselective Oxidations

Cu-Albumin Artificial Enzymes with Peroxidase and Oxidase Activity for Stereoselective Oxidations

Metabolomic analysis of the browning and browning inhibition pulp of Fuji apple at different ripening stages

Apples at different ripening stages display distinct processing properties and browning characteristics in products. This study aimed to identify differential metabolites and metabolic pathways of browning pulp and browning inhibition pulp of Fuji apple across four ripening stages (M1–M4), corresponding to days after full bloom (DAFB: 148, 155, 162, and 171). We investigated the physicochemical characteristics, browning-related enzyme activities, and metabolomic profiles of apples at the four stages, revealing defensive metabolic changes associated with browning throughout ripening. Specifically, the browning rate in apples increased with ripening, peaking before declining in the late stages, and exhibited positive correlations with activities of polyphenol oxidase (PPO), peroxidase (POD), and catalase (CAT), and negative correlations with superoxide dismutase (SOD), phenylalanine ammonia-lyase (PAL), and H2O2 levels. Metabolomic profiling identified 315, 393, and 243 distinct metabolites in fresh control (FC), browning pulp (BR), and browning-inhibited pulps (CM) of apple at the four ripening stages, respectively. KEGG enrichment analysis revealed that FC and BR of the four ripening apples were differentiated by phenylpropanoid biosynthesis, while CM was featured by flavonoid biosynthesis. The characterized differential metabolites in BR were changed to α-linolenic acid metabolism with ripening, while those in CM were from flavonoid and phenylpropanoid biosynthesis. Furthermore, the in-depth analysis revealed 40 significantly differential metabolites associated with amino acid, nucleotide, coenzyme, and vitamin metabolism, potentially modulating the stress-responsive cellular redox balance. This research provides critical insights for browning prevention in the processing of fruits at various ripening stages.

Evaluating the nutrient composition and antioxidant properties of orange (Citrus sinensis) peels through Penicillium camemberti-based solid-substrate fermentation

Citrus by-products, especially orange peels, are a significant global waste issue, driving research into management solutions. Solid-substrate fermentation is a promising method to convert this waste into valuable resources, enhancing its medicinal and nutritional potential while addressing environmental and economic concerns in food waste management. Therefore, this study was carried out to evaluate the impact of solid-substrate fermentation (SSF) with Penicillium camemberti on the nutrient profile, antioxidative properties, and potential neuroprotective effects of orange peels in AlCl3 (Al)-induced neurotoxicity in fruit fly (Drosophila melanogaster) model. Orange peels were collected, air-dried to a constant weight, and subjected to a 10-day SSF process with Penicillium camemberti. Post-fermentation, in vitro nutritional profiling, and antioxidant assays were conducted, alongside in vivo assessments of the neuroprotective effects on survival rate, memory index, monoamine oxidase (MAO) activity, and endogenous antioxidant markers on Al-induced fruit flies were determined. The results showed that fermentation with Penicillium camemberti significantly enhanced the nutritional composition of the orange peels compared to their unfermented counterparts. The antioxidant properties of fermented orange peels were significantly (p < 0.05) increased, as evidenced by increased DPPH scavenging activity (81.68 ± 0.18) and ferric reducing antioxidant power (10.77 ± 0.27). Additionally, biochemical assays in vivo revealed a significant improvement in survival rates and memory indices in Al-induced flies. Also, monoamine oxidase (MAO) levels were significantly reduced, while glutathione S-transferase (GST) levels were significantly (p < 0.05) elevated in the induced flies fed with the fermented samples. Conclusively, this study highlights the capability of Penicillium camemberti fermentation in converting waste into valuable resources, enhancing the nutrient profile of citrus peels for applications in livestock feed and potential therapeutic interventions for degenerative disorders.

The alleviating effects and mechanisms of Lactiplantibacillus plantarum MC14 on hyperuricemia in mice

Hyperuricemia (HUA) is a chronic disorder resulting from purine metabolic dysregulation. This research explored the alleviating effects and potential mechanisms of Lactiplantibacillus plantarum MC14 on HUA in a mouse model. Further, it investigated the impact of MC14 intervention on the intestinal flora and metabolites of HUA model mice. Results indicated that the activity of MC14 in alleviating HUA may be linked to its abilities to lower serum levels of uric acid, creatinine, and blood urea nitrogen, reduce inflammation, alleviate renal tissue damage, enhance uric acid excretion, inhibit the overactivation of the PI3K/AKT/mTOR signaling pathway, suppress hepatic adenosine deaminase and xanthine oxidase activities, competitively absorb nucleosides and nucleobases, and regulate the intestinal flora. Our research demonstrates that MC14 is a potential candidate for developing novel therapeutics for hyperuricemia.

Inhibitory potential of 7-hydroxycoumarin-3-carboxylic acid against tyrosinase and its effect on the preservation of fresh-sliced apples

Excessive tyrosinase expression leads to pigmented diseases in humans and browning in plants, necessitating effective tyrosinase inhibitors. This study investigated the inhibitory effect and mechanism of 7-hydroxycoumarin-3-carboxylic acid (7-HC-3-CA) on tyrosinase. Using UV–visible absorption spectroscopy, we found that 7-HC-3-CA effectively inhibited tyrosinase activity, with an IC50 value of 364 ± 1.3 μM. Enzyme kinetics, fluorescence methods and molecular simulation techniques revealed that 7-HC-3-CA acted as a reversible and competitive inhibitor, forming a stable complex with tyrosinase through hydrophobic interactions and hydrogen bonding. This altered the microenvironment of Tyr and Trp residues, causing the structural stretching and conformational changes that diminish catalytic activity.Preservation experiments demonstrated that 0.5 mM 7-HC-3-CA significantly reduced mass loss and decreased browning of fresh-sliced apples. It also lowered polyphenol oxidase activity from 0.22 to 0.18 and delayed phenolic oxidation, enhancing total phenolic content from 0.34 to 0.54, thereby controlling browning and extending storage life. Cell assays indicated that 0.5 mM 7-HC-3-CA had no significant impact on cell proliferation, with viability over 80 %. Acute toxicity tests proved that 0.5 mM of 7-HC-3-CA is completely non-lethal to KM mice. In conclusion, this study confirmed 7-HC-3-CA was a viable and safe antibrowning agent and revealed its potential application in the field of food preservation.

Melatonin Rinsing Treatment Associated with Storage in a Controlled Atmosphere Improves the Antioxidant Capacity and Overall Quality of Lemons.

Antioxidant capacity is one of the most important biological activities in fruits and vegetables and is closely related to human health. In this study, 'Eureka' lemons were used as experimental materials and stored at 7-8 °C MT (melatonin, 200 μmol, soaked for 15 min) and CA (controlled atmosphere, 2-3% O2 + 15-16% CO2) individually or in combination for 30 d. The changes in lemon fruits' basic physicochemical properties, enzyme activities, and antioxidant capacities were studied. Comparing the combined treatment to the control, the outcomes demonstrated a significant reduction in weight loss, firmness, stomatal opening, and inhibition of polyphenol oxidase (PPO) and peroxidase (POD) activities. Additionally, the combined treatment maintained high levels of titratable acidity (TA), vitamin C (VC), total phenolic content (TPC), and antioxidant capacity and preserved the lemon aroma. Meanwhile, the correlation between fruit color, aroma compounds, and antioxidant capacity was revealed, providing valuable insights into the postharvest preservation of lemons. In conclusion, the combined treatment (MT + CA) was effective in maintaining the quality and antioxidant capacity of lemons.

Deciphering the mechanisms underlying the neuroprotective potential of kaempferol: a comprehensive investigation.

Neurodegenerative disorders are characterized by neuronal degradation, dysfunction, or death within the CNS. Oxidative and inflammatory stress play crucial roles in the pathogenesis of various neurodegenerative diseases. The interplay between these stressors and dysregulated cellular signaling pathways contributes to neurodegeneration. Downregulation of NRF-2 compromises antioxidant defense, exacerbating neuronal damage, while increased TLR-4/MAPK and TLR-4/NF-κB signaling promotes neuroinflammation. Excessive ROS production by NADPH oxidase leads to oxidative damage and neuronal apoptosis. The strategies targeting NRF-2, TLR-4-mediated inflammatory stress, and NADPH oxidase activity promise to mitigate neuronal damage and halt the progression of the disease. Kaempferol is a flavonoid polyphenol antioxidant found abundantly in various fruits and vegetables, including apples, grapes, tomatoes, and broccoli. It is widely found in medicinal plants including Equisetum spp., Sophora japonica, Ginkgo biloba, and Euphorbia pekinensis (Rupr.). A substantial body of in vitro and in vivo evidences have demonstrated the neuroprotective potential of kaempferol against neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease. Kaempferol demonstrates multifaceted potential in mitigating neuroinflammation, apoptosis, and oxidative stress in different neurodegenerative diseases through the modulation of various pathways including NRF-2, NADPH oxidase, TLR-4/MAPK, and TLR-4/NF-κB. This review article was developed through a comprehensive analysis and interpretation of research published between 2009 and 2024, sourced from multiple scientific databases, including PubMed, Scopus, ScienceDirect, and Web of Science. This review aims to provide an in-depth overview of the neuroprotective effects of kaempferol, focusing on its underlying molecular mechanisms. A total of 24 research evidence were included to elucidate the molecular pathways by which kaempferol exerts its protective effects against neurodegenerative diseases.

Effects of Silicon on Development and Controlling of Powdery Scab in Irish Potato (Solanum tuberosum)

Effects of different silicon levels on plant height, stem diameter, disease incidence and severity and its activity on polyphenol oxidase and peroxidase enzymes on powdery scab caused by Spongospora subterranean on Irish potatoes (BP1) was assessed. This was a greenhouse study at the University of Zimbabwe Crop Science department. A mixture of 50% sterilised vermiculite and 50% sterilised sand was used as growing media. 0, 250, 500 and 750ppm silicon concentrations were used. Irrigation water, other fertilizers and insecticides applied were made uniform across all treatments. Variations among treatments were monitored from three weeks after planting then on weekly basis for the coming eighty weeks. Silicon concentrations showed significance difference (p&lt;0.001) on plant height and stem diameter of Irish potatoes. It proved to play a significant role in the growth of the potato plants. Silicon levels showed no significant difference on powdery scab incidence with all plants getting diseased. Silicon reduced the infestation severity at high concentrations. It also increased the activity of polyphenol oxidase and peroxidase enzymes in potatoes at different response rates. Results from the study indicates great potential of silicon based fertilizers in controlling powdery scab as well as growth rate of Irish potatoes.

Anti-inflammatory Activity of 1-Substituted Glyoxal β-Carboline Derivatives

The anti-inflammatory properties of β-carbolines have been widely studied, highlighting their potential in treating inflammatory disorders. This research investigates the anti-inflammatory activity of selected 1-substituted glyoxal β-carboline derivatives, achieved through a one-step conversion of 5-hydroxy-L-tryptophan with activated glyoxal, without forming tetrahydro-β-carboline (THβC) intermediates. These derivatives (4e-g) were synthesized successfully without requiring expensive metal catalysts, prolonged reaction times, or stringent reaction conditions, and yielded moderate amounts. Our findings indicate that all the derivatives significantly inhibit xanthine oxidase (XO) activity, leading to a reduction in reactive oxygen species (ROS) and free radicals. This inhibition disrupts the inflammatory cascade and attenuates the inflammatory response.

Exploring the antifungal activity of clove oil (Syzygium aromaticum) against wilt disease caused by Fusarium equiseti in bitter gourd (Momordica charantia L.)

This study investigates the isolation and characterization of Fusarium equiseti, a fungal pathogen causing wilt in bitter gourd. It explores the antifungal activity of essential oils, particularly clove oil, as a natural management approach. The pathogen was isolated from wilt-infected bitter gourd stems and it was confirmed as F. equiseti morphologically by the presence of three-septate falcate macroconidia and globose microconidia and also confirmed molecularly by PCR amplification of the ITS region (PP501044.1). Among the tested essential oils, clove oil demonstrated the highest mycelial growth inhibition (100%) at a concentration of 0.5%, followed by peppermint, wintergreen and tea tree oils. In comparison, neem oil exhibited the least inhibition (15.54%). GC-MS analysis of clove oil revealed 38 compounds, where eugenol is the predominant compound that played a crucial role in antifungal activity. Additionally, metabolic analysis revealed several enriched pathways in F. equiseti during its interaction with clove oil, particularly those involved in lipid metabolism and energy production. Pot culture experiments confirmed the efficacy of clove oil in reducing disease severity and incidence in bitter gourd, achieving a 66.99 % reduction when combined with soil application.Furthermore, clove oil-treated plants showed increased activity of defense-related enzymes, including peroxidase (PO), polyphenol oxidase (PPO) and phenylalanine ammonia-lyase (PAL), suggesting the induction of systemic resistance. This study highlights the potential of clove oil as an eco-friendly alternative to synthetic fungicides for managing F. exquisite-induced wilt in bitter gourd. Future research should focus on optimizing clove oil application methods and understanding its interactions with fungal pathogens at the molecular level to enhance its efficacy in sustainable disease management.

Cow Placenta Extract Ameliorates Cyclophosphamide-Induced Intestinal Damage by Enhancing the Intestinal Barrier, Improving Immune Function, and Restoring Intestinal Microbiota

Immunosuppression undermines intestinal barrier integrity. Cow placenta extract (CPE) primarily consists of active peptides with immunomodulatory and antioxidant effects. This study aimed to examine the preventive effect of CPE against intestinal damage induced by cyclophosphamide (Cy) in immunosuppressed mice. Thirty-six mice were randomly allocated into three groups: control group (C), model group (M), and treatment group (CPE). The mice in the CPE group were provided with 1500 mg/kg/day of CPE via gavage. In the last 3 days, mice in the groups M and CPE received intraperitoneal injections of 80 mg/kg/day of Cy. The results showed that CPE improved intestinal barrier function by decreasing serum d-Lactate (D-LA) levels and diamine oxidase (DAO) activity, while elevating the relative expression of Occludin, zonula occludens-1 (ZO-1), and mucin-2 (MUC-2) mRNA. Additionally, CPE improved the immune organ index and elevated the levels of secretory immunoglobulin A (sIgA), superoxide dismutase (SOD), interleukin-1beta (IL-1β), interleukin-4 (IL-4), interleukin-10 (IL-10), and tumor necrosis factor-α (TNF-α) in the intestine, thereby enhancing intestinal mucosal immune function. Furthermore, CPE improved the diversity of intestinal microbiota and increased the abundance of Candidatus_Saccharimonas, Psychrobacter, and Enterorhabdus, which promoted the proper functioning of the intestines. These findings suggest that CPE effectively ameliorates Cy-induced intestinal damage by enhancing the intestinal barrier, improving immune function, and restoring intestinal microbiota.

Transcriptome sequencing analysis of the effects of 1-MCP and ethephon treatments on the storage quality of Pleurotus pulmonarius

Pleurotus pulmonarius has gained a lot of popularity among consumers due to its exquisite flavor and several nutritional benefits. However, P. pulmonarius fruiting bodies are susceptible to deterioration in quality following harvest. To investigate the impact of 1-methylcyclopropene (1-MCP) and ethephon treatments on P. pulmonarius quality degradation, its antioxidant and sensory quality indices were assessed following treatment with 0.75μL/L 1-MCP and 0.05 % ethephon. Transcriptomic sequencing was performed on P. pulmonarius at different treatment time points. Based on the findings, 1-MCP treatment resulted in the maintenance of high firmness levels, increased glutathione content, and superoxide dismutase activity. At the same time, it lowered membrane permeability, slowed the rate of weight loss, reduced the levels of malondialdehyde, boosted antioxidant capacity, and resulted in improved storage quality. On the other hand, the ethephon treatment hastened the browning of P. pulmonarius by raising ethylene release, polyphenol oxidase activity, and b* value. Based on the transcriptome analysis, the number of differentially expressed genes (DEGs) on the 5th day was much higher than that on the 1st and 9th day of storage. Overall, 5422 DEGs were significantly enriched in the different treatment groups. Moreover, 62 DEGs exhibited significant differences between each treatment group and were mainly enriched in the pathways of 2-oxocarboxylic acid metabolism, glycerolipid metabolism, and biosynthesis of nucleotide sugars, which were closely related to the storage quality of P. pulmonarius. This study provides a theoretical basis for using 1-MCP for the storage and preservation of P. pulmonarius using 1-MCP, which has significant theoretical and practical implications.

Advancements and Applications of Single-Atom Nanozymes in Sensing Analysis

Single-atom nanozymes, with their atomically dispersed metal active sites, distinctive atom utilization rate, and tunable electronic structure, demonstrate great promise in the field of sensing analysis. This paper reviews the latest research progress on single-atom nanozymes in sensing applications. We classify single-atom nanozymes based on both their structural characteristics, such as carbon-based carriers, frameworks and their derivatives, metal oxides, metal sulfides, and organic polymer carriers, and their unique catalytic properties, including peroxidase, oxidase, catalase, superoxide dismutase, and multi-enzyme mimetic activities. Furthermore, we discuss the application of single-atom nanozymes in the sensitive detection of biological small molecules, antioxidants, ions, enzyme activities and their inhibitors, as well as cells and viruses. Finally, we highlight the opportunities and challenges for advancing the practical application and further research of single-atom nanozymes in the field of sensing analysis.

In-vitro &amp; In-vivo Studies on Antimicrobial and Plant Growth Promoting Efficacy of Fluorescent Pseudomonads

Aims: Excessive use of chemical fungicides cause environmental pollution and its residual effects are deleterious for human and animal consumption. So, application of biological control agents in IDM is an ecofriendly complement to manage the diseases as well as to protect the environment. PGPRs are free living microorganisms which have antimicrobial properties as well as exert beneficial effects to plant growth. Study Design: This present study has been designed to identify potential indigenous fluorescent Pseudomonads strains from different crop ecosystems under Eastern Gangetic plains of West Bengal. Study of Plant growth promoting properties and antimicrobial properties were done under both in-vitro and in vivo condition. Place and Duration of Study: Uttar Banga Krishi Viswavidyalaya, Pundibari, Cooch Behar, West Bengal, Duration 03years Methodology: Under this experiment 22 bacterial isolates were isolated and purified from different rhizosphere. Isolates were identified based on different biochemical test like catalase, oxidase activity, citrate utilization. The major plant growth promoting properties like P, K and Zn solubilisation efficiency were tested. In-vitro antimicrobial properties were also tested like HCN production, Volatile and non volatile compounds production etc. Based on in-vitro performance, best performing isolate was selected for in-vivo in Lentil against Stemphylium botryosum, a major disease causing fungi of lentil. IDM practice was done in three stages like Seed treatment, Prophylactic spray and Therapeutic spray and three lentil variety WBL 77(Maitree), Pusa Ageti and MN12 were used. Results: Most of the isolates showed positive result in biochemical tests and performed well i.r.o. PGP properties and antimicrobial properties. In field trial UBPF5 gave a promising result. PF5 isolate was identified through 16S rRNA based molecular method and sample showed 99.25% similarity with Pseudomonas gessardii based on nucleotide homology and phylogenetic analysis. In comparison to different combination of treatments cuprous chloride as seed treatment, Pseudomonas sp. as prophylactic spray and for therapeutic purpose Boscalid + Pyroclostrobin were found mostly efficient in respect of disease incidence as well as plant growth and yield. Prophylactic spray with Pseudomonas sp. in combination with biological seed treatment and therapeutic application of fungicide has resulted in 26-38% reduction in disease incidence and 28-32% increment in yield. Conclusion: So, use of PGPR in combination with chemical fungicides is an eco-friendly tool to manage plant diseases in a sustainable manner.

The Physiological Effect of Trichoderma viride on Melon Yield and Its Ability to Suppress Rhizoctonia solani

Melon damping off, which has a negative impact on melon quality and yield, can be safely and effectively managed with Trichoderma. Melon cultivar ‘Longtian No. 1’ was evaluated at both the adult and seedling stages in a pot experiment. The Rs and PD liquids were utilized as CK1 and CK2, respectively. Trichoderma viride Tv286 treatments T1B, T2B, T3B, and T4B were used based on Rs at concentrations of 104, 105, 106, and 107 CFU·g−1, respectively. The impact of several treatments on the antioxidant system and seedling quality of melon were assessed at 15, 25, and 35 days after sowing. We examined the effects of several treatments on melon quality, yield attributes, and physiological and biochemical markers during the adult stage at 10, 20, and 30 days after pollination. The effects of several treatments on melon damping off were also studied. Applying T. viride Tv286 at different rates effectively increased the activities of enzymes, including catalase (CAT), peroxidase (POD), superoxide dismutase (SOD), ascorbate peroxidase (APX), and polyphenol oxidase (PPO), in the leaves of melon seedlings, significantly reduced the malondialdehyde (MDA) content, and improved the root–shoot ratio and seedling strength index. In terms of its influence on promoting the effect of antioxidant system indicators, T3B performed well. Melon seedlings treated with T3B showed higher CAT, POD, SOD, APX, and PPO activities in their leaves 35 days after sowing compared to CK1 (189.74, 169.61, 175.36, 224.20, and 477.39%, respectively). The strong seedling index and root–shoot ratio showed improvements of 130.43 and 79.71%, respectively, and the MDA content dropped by 35.66% at 35 days after sowing compared to CK1. Varying the rates at which T. viride Tv286 was applied increased the nitrate reductase (NR) activity and nitrate nitrogen, proline (Pro), chlorophyll, soluble sugar, and soluble protein contents in mature melon leaves, increasing melon quality and yield. T3B is the most effective marketing campaign. Compared to CK1, mature T3B leaves had higher NR activity, nitrate nitrogen content, chlorophyll content, soluble sugar content, soluble protein content, and Pro content 30 days after melon pollination (100.40, 135.17, 68.59, 93.65, 158.13, and 238.67%, respectively). The soluble solids, soluble protein, soluble sugar, vitamin C contents, and yield of melon fruit increased by 50.07, 126.82, 60.62, 70.79, and 61.45%, respectively, at 30 days after melon pollination compared to CK1. Optimal management of melon damping off can be accomplished with the application of T. viride Tv286 at different concentrations, with T3B exhibiting the best effect. The control effects reached 90.48 and 72.99% at the seedling and adult stages, respectively. Overall, T. viride Tv286 improved seedling quality, damping off control efficacy, melon yield and quality, and the antioxidant system during the seedling stage and enhanced physiological and biochemical characteristics during the adult stage. This study indicates the potential of T. viride Tv286 conidia as a biological control agent because it can prevent plant disease, increase yield, and improve quality.