Antagonistic Activity Research Articles

Strain-specific features of Pleurotus ostreatus growth in vitro and some of its biological activities

BackgroundThe production of Pleurotus ostreatus mycelium as a promising object for use in food and other industries is hampered by a lack of information about the strain-specificity of this fungus mycelium growth and its acquisition of various biological activities. Therefore, this research aimed to investigate mycelial growth of different P. ostreatus strains on varies solid and liquid media as well as to evaluate strains antagonistic, antibacterial, antiradical scavenging activities, and total phenolic content.ResultsPotato Dextrose Agar medium was suitable for all strains except P. ostreatus strain 2460. The best growth rate of P. ostreatus 2462 strain on solid culture media was 15.0 ± 0.8 mm/day, and mycelia best growth on liquid culture media—36.5 ± 0.2 g/l. P. ostreatus strains 551 and 1685 were more susceptible to positive effect of plant growth regulators Ivin, Methyur and Kamethur. Using of nutrient media based on combination of natural waste (amaranth flour cake and wheat germ, wheat bran, broken vermicelli and crumbs) has been increased the yield of P. ostreatus strains mycelium by 2.2–2.9 times compared to the control. All used P. ostreatus strains displayed strong antagonistic activity in co-cultivation with Aspergillus niger, Candida albicans, Issatchenkia orientalis, Fusarium poae, Microdochium nivale in dual-culture assay. P. ostreatus 2462 EtOAc mycelial extract good inhibited growth of Escherichia coli (17.0 ± 0.9 mm) while P. ostreatus 2460 suppressed Staphylococcus aureus growth (21.5 ± 0.5 mm) by agar well diffusion method. The highest radical scavenging effect displayed both mycelial extracts (EtOH and EtOAc) of P. ostreatus 1685 (61 and 56%) by DPPH assay as well as high phenolic content (7.17 and 6.73 mg GAE/g) by the Folin-Ciocalteu’s method. The maximal total phenol content (7.52 mg GAE/g) demonstrated of P. ostreatus 2461 EtOH extract.ConclusionsIt is found that the growth, antibacterial, antiradical scavenging activity as well as total phenolic content were dependent on studied P. ostreatus strains in contrast to antagonistic activity. The proposed culture mediums of natural waste could be an alternative to commercial mediums for the production mycelial biomass of P. ostreatus strains.

Biological Control Effect of Antagonistic Bacteria on Potato Black Scurf Disease Caused by Rhizoctonia solani

Potato black scurf, caused by Rhizoctonia solani, is a severe soil-borne disease that affects the quality and production of potatoes worldwide. In our study, we used Paenibacillus polymyxa YF and Bacillus amyloliquefaciens HT to determine the antagonistic ability of R. solani, with a particular focus on the antagonistic action of P. polymyxa YF to R. solani and its biocontrol effect on potato black scurf. In fermentation, filtrate assay, 50% filtrate of P. polymyxa YF and B. amyloliquefaciens HT inhibited the growth of R. solani by 85.55% and 82.86%, respectively. Microscopic observations showed notable morphological changes with mycelial collapse, atrophy, and deformation following treatment with the antagonistic filtrates. Moreover, cell membrane permeability results showed increased conductivity in bacteria-treated samples compared to the control. P. polymyxa YF exhibited stable colonization on potato plants and secreted various extracellular enzymes (protease, amylase, and cellulase), along with the synthetic substances with growth-promoting effects, such as siderophores and Indole-3-acetic acid (IAA). Whether it is in the excised tissue inoculation or potted experiment, the negative control showed the highest rank of disease symptoms. In the pot experiment, after YF treatment, physiological parameters showed remarkable changes in plant height, root length, stem thickness, and dry and fresh weight. Compared to blank control, the activities of the four resistant enzymes increased significantly in the P. polymyxa YF treatment group. The upregulation in the P. polymyxa YF group was 4.04, 0.54, 0.46, and 3.10 times, respectively. PCR analysis identified genes in both bacterial strains coding for antimicrobial lipopeptides, including fenB, ituC, and srfAA, which are associated with fengycin, iturin, and surfactin synthesis. These findings demonstrated that P. polymyxa YF has a prominent antagonistic effect on R. solani, suggesting its potential as an effective biological control agent for controlling potato black scurf.

Enterococcus mundtii A2 biofilm and its anti-adherence potential against pathogenic microorganisms on stainless steel 316L.

Pathogenic bacterial biofilms present significant challenges, particularly in food safety and material deterioration. Therefore, using Enterococcus mundtii A2, known for its antagonistic activity against pathogen adhesion, could serve as a novel strategy to reduce pathogenic colonization within the food sector. This study aimed to investigate the biofilm-forming ability of E. mundtii A2, isolated from camel milk, on two widely used stainless steels within the agri-food domain and to assess its anti-adhesive properties against various pathogens, especially on stainless steel 316L. Additionally, investigations into auto-aggregation and co-aggregation were also conducted. Plate count methodologies revealed increased biofilm formation by E. mundtii A2 on 316L, followed by 304L. Scanning electron microscopy (SEM) analysis revealed a dense yet thin biofilm layer, playing a critical role in reducing the adhesion of L. monocytogenes CECT 4032 and Staphylococcus aureus CECT 976, with a significant reduction of ≈ 2 Log CFU/cm2. However, Gram-negative strains, P. aeruginosa ATCC 27853 and E. coli ATCC 25922, exhibit modest adhesion reduction (~ 0.7 Log CFU/cm2). The findings demonstrate the potential of applying E. mundtii A2 biofilms as an effective strategy to reduce the adhesion and propagation of potentially pathogenic bacterial species on stainless steel 316L.

(166) Safety of Flibanserin in Men with Hypoactive Sexual Desire Disorder

Abstract Introduction Flibanserin possesses unique properties and displays selective agonistic and antagonistic activity against serotonin receptors. Originally, its primary application was in the treatment of hypoactive sexual desire disorder (HSDD) in women, where it showed promising results in improving sexual desire. However, as our understanding of its mechanism of action has expanded, researchers have begun to explore its potential utility in treating HSDD in males. This emerging trend has led to an increased interest in the use of flibanserin as a potential therapeutic option for men experiencing a decline in sexual desire. Objective We aimed to elucidate the demographic profiles, clinical attributes, and comprehensive safety implications of men receiving off-label flibanserin at our institution. Methods A retrospective analysis encompassing a cohort of men who initiated flibanserin treatment between July 2022 and July 2023 was performed. Basic demographic information, levels of total and free testosterone, pertinent medical history, scores from the International Index of Erectile Function (IIEF) and Patient Health Questionnaire-9 (PHQ-9), and overall manifestation of side effects were collected. Descriptive statistics were performed. Results A total of 26 patients were identified, with a mean age of 57.9 years (range, 31–80 years). Among these patients, seven had a prior diagnosis of depression and had previously received treatment with selective serotonin reuptake inhibitors (SSRIs). The mean levels of total testosterone and free testosterone were found to be 611.3 ng/dL and 116.8 pg/mL, respectively. Notably, a significant majority of patients (22 of 26 [81.4 %]) were diagnosed with erectile dysfunction. Importantly, all patients exhibited euthyroid status. The mean baseline score on the PHQ-9 was 5.30 (ranging, 0–17), indicating mild depressive symptoms, whereas the mean IIEF total score was 40 (range, 6–67). Furthermore, the mean score on the IIEF-desire subdomain was 5.65 (ranging: 2–10), reflecting relatively diminished levels of sexual desire. Upon conducting a follow-up assessment at the 3-month mark, it was observed that seven patients discontinued flibanserin medication, with reasons such as ineffectiveness and high cost being cited as the primary factors. Notably, only one patient (3.8%) discontinued the medication because of side effects. Conclusions In summary, our study sheds light on the fundamental characteristics associated with off-label utilization of flibanserin in men with HSDD, underscoring the increasing interest in investigating its potential therapeutic advantages within this specific population. However, additional research is warranted to comprehensively elucidate the clinical benefits and potential risks of flibanserin administration in men. Such investigations will contribute to a more thorough understanding of its efficacy and safety profile. Disclosure Any of the authors act as a consultant, employee or shareholder of an industry for: Disclosures: Consultant for AbbVie, Marius, Tolmar, Endo, Petros, Boston Scientific, Coloplast Investor: Sprout.

Regioselective synthesis of new EWG-Bearing 3-benzoyl-2-phenylbenzofurans by one-pot intramolecular acylation/thermal cyclization of phosphoranes and their CB1 antagonist activity

(Benzoylmethylene)triphenylphosphoranes are useful intermediates in the synthesis of 3-benzoyl-2-phenylbenzofurans. Under Wittig conditions, they allow the simultaneous preparation of two 3-acyl regioisomers. Starting from the o-[(benzoyloxy)benzylidene]triphenylphosphonium salt bearing electron withdrawing groups (EWGs) on the ortho-benzoyloxy ring (nitro, cyano and trifluoromethyl groups), we developed an improved regioselective synthetic strategy, via tandem ylide acylation and thermal cyclization of the acyl ylide intermediate. Using our optimized method, only one 3-acyl regioisomer was obtained and the yields were highly improved (up to 92 %) comparing to the previously reported method, expanding the scope of synthesis to a wide variety of new EWG-containing 3-benzoyl-2-phenylbenzofurans. The synthesized compounds were evaluated for their activity on CB1 receptors. In particular, some of these compounds displayed activity as CB1 antagonists.

Discovery of a novel androgen receptor antagonist, MEL-6, with stereoselective activity and optimization of its metabolic stability

A new chemical scaffold with antagonistic activity towards the androgen receptor (AR) was identified. The parent compound, (3-Methoxy-N-[1-methyl-2-(4-phenyl-1-piperazinyl)−2-(2-thienyl)ethyl]benzamide) referred to as MEL-6, binds in the ligand binding pocket of AR and induces an antagonistic conformation of the ligand binding domain, even in presence of the antagonist-to-agonist switch mutations W741C, T877A and F876L-T877A. MEL-6 has antiproliferative effects on several AR positive prostate cancer cell lines. We further identified AR as the specific target of MEL-6 since it demonstrates little effect on other steroid receptors. In LNCaP cells it also inhibits the androgen-regulated transcriptome. These findings identify MEL-6 as a promising candidate for treatment of patients with prostate tumors that have become resistant to current clinically used AR antagonists. Analytical studies on the chemical composition of MEL-6 identified the presence of four isomers (two enantiomeric pairs), among which one isomer is responsible for the antiandrogenic activity. We therefore developed a synthetic route towards the selective preparation of the active enantiomeric pair. Various MEL-6-like analogues had improved metabolic stability while maintaining antiandrogenic activity. Metabolite identification of MEL-6 derivatives pinpointed N-dealkylation of the piperazine as the main mode for inactivation by liver enzymes. For further structural optimization, MEL-6 derivatives were purchased or synthesized having alterations on the N-phenyl group of the piperazine, the benzoyl group and additionally substituting the thiophen-2-yl ring of MEL-6 to a phenyl ring. This optimization process resulted in compound 12b with sustained AR inhibition and a 4-fold increased half-life due to the 1-(5-chloro-2-methylphenyl)-piperazine substitution, thienyl-to-phenyl substitution and chloro in para-position of the benzoyl group.

ESCHERICHIA COLI phenotypic characteristics and antagonistic activity in opisthorchiasis invasion

Opisthorchis felineus invasion in human causes inflammatory and dyskinetic disorders of the gastrointestinal tract accompanied by altered phenotypic characteristics in colon microbiota. The aim of research — study an impact of the Escherichia coli isolate phenotypic characteristics on Klebsiella spp. bacteria, isolated from colonic contents of patients with diagnosed opisthorchiasis as well as E. coli antagonistic activity. Materials and methods. The phenotypic properties of 54 E. coli isolates and 8 genus Klebsiella isolates obtained from colonic contents of patients with diagnosed opisthorchiasis were assessed. Identification of isolates and analysis of proteomic profiles were performed using Maldi BioTyper 3.0 software. 204 co-cultivation datasets were analyzed investigating antagonistic activity of E. coli isolates with varying properties on Klebsiella spp. E. coli and Klebsiella spp. isolates were examined by whole genome sequencing. Results. E. coli bacteria with typical phenotypic characteristics showed significantly more prominent antagonistic activity against Klebsiella spp. A significantly higher level of antagonistic activity against K. oxytoca bacteria vs K. pneumoniae strains. The proteomic bacterial strain profiles were divided into clusters depending on the level of antagonistic activity. E. coli molecular serotyping for O- and H-antigens revealed the genes of enterotoxigenic, enteroinvasive and extraintestinal pathogens in 60.0% of cases. Strains with the highest antagonistic activity index, which are carriers of the genes typical to enterotoxigenic E. coli sequence serotypes O6:H1 and O6:H5, were identified. The genome of such strains consisted of the largest number of virulence gene complexes: adhesins, invasins, toxins, bacteriocins. Multilocus sequence typing and sequence serotyping of E. coli and K. pneumoniae strains established their heterogeneity; K. oxytoca isolates were identified as ST242 and ST176. All strains were characterized by homology of antibiotic resistance markers (oqxA, oqxB, fosA) and a variety of beta-lactam resistance gene variants. Conclusion. It was found that E. coli isolates with typical phenotypic characteristics and carriers of virulence gene complexes exhibited significantly more pronounced antagonistic activity against Klebsiella spp. isolated from colonic contents of patients with diagnosed opisthorchiasis.

Exploring the Function of (+)-Naltrexone Precursors: Their Activity as TLR4 Antagonists and Potential in Treating Morphine Addiction.

Disruptions in the toll-like receptor 4 (TLR4) signaling pathway are linked to chronic inflammation, neuropathic pain, and drug addiction. (+)-Naltrexone, an opioid-derived TLR4 antagonist with a (+)-isomer configuration, does not interact with classical opioid receptors and has moderate blood-brain barrier permeability. Herein, we developed a concise 10-step synthesis for (+)-naltrexone and explored its precursors, (+)-14-hydroxycodeinone (1) and (+)-14-hydroxymorphinone (3). These precursors exhibited TLR4 antagonistic activities 100 times stronger than (+)-naltrexone, particularly inhibiting the TLR4-TRIF pathway. In vivo studies showed that these precursors effectively reduced behavioral effects of morphine, like sensitization and conditioned place preference by suppressing microglial activation and TNF-α expression in the medial prefrontal cortex and ventral tegmental area. Additionally, 3 displayed a longer half-life and higher oral bioavailability than 1. Overall, this research optimized (+)-naltrexone synthesis and identified its precursors as potent TLR4 antagonists, offering potential treatments for morphine addiction.

The beneficial endophytic microbes enhanced tobacco defense system to resist bacterial wilt disease

BackgroundThe vital role of rhizosphere microbiome in protecting plants against pathogen infection has been well characterized. By contrast, beneficial effects of the plant endophytic microbiome and interactions with plants remain poorly understood. Here, we integrated microbial community analysis, culture-based methods and plant defense gene quantification to systematically investigate the responses of endophytic root and stem microbiomes and the defense system of the tobacco plant to Ralstonia solanacearum, a bacterial pathogen causing bacterial wilt disease worldwide.ResultsAn obvious reduction of community diversity and changes of microbial composition were observed in tobacco root and stem compartments upon R. solanacearum infection. Beneficial endophytic microbes were enriched in both diseased root and stem compartments, and beneficial microbes enriched in roots were more diverse than those in stems. Several beneficial bacteria enriched in diseased roots showed positive correlations with the pathogen abundance and exhibited great antagonistic activities against R. solanacearum. At the same time, the expression of key genes participating in plant defense signaling pathways and activities of plant defense enzymes were activated with R. solanacearum infection. Inoculation of beneficial endophyte Burkholderia ASV_550 in soils could greatly enhance the tobacco defense system in the presence of pathogen and decrease the disease incidence.ConclusionsThe recruited beneficial microbes exhibited an enhancement of the defense system of host plants. This work provides endophyte evidence for the “cry for help” strategy in plants and advances the current understanding of plant–microbe interactions in resisting plant disease.Graphical

Isolation, Characterization, and Screening of Endospore Forming Endophytic Bacteria from Cowpea [Vigna unguiculata (L.) Walp.] for Plant Growth Promotion and Abiotic Stress Mitigation

We performed isolation and characterization of endospore forming endophytic bacteria (EEB) from endorhizospheric region of healthy bush cowpea var. Bhagyalakshmi. All the EEB isolates were evaluated for their ability to produce plant growth promoting traits such as production of indole acetic acid (IAA), gibberellic acid, ammonia, ACC deaminase, volatile organic compounds and siderophore, and capacity for nitrogen fixation, and solubilization of phosphorus and potassium. Roll towel assay was used for assessing the seedling vigour index of cowpea after seed priming with the EEB isolates. Based on growth promotion and seedling vigour index, seven superior bacterial isolates were selected, and antagonistic activity against the fungal pathogens Fusarium oxysporum, Rhizoctonia solani, Colletotrichum sp., Phytophthora sp., and Pythium sp., was assayed. The isolates were pooled together to form a consortium and biopriming of cowpea seeds were done. Bioprimed seeds were tested for plant growth promotion and abiotic stress management in cowpea under protray condition. The seedlings of the bioprimed cowpea seeds showed better seedling vigour index and stress tolerance compared to hydro-primed seeds and the unprimed control. EEB isolated from the host plant could be developed as plant growth promoting bioagents.

A GIPR antagonist conjugated to GLP-1 analogues promotes weight loss with improved metabolic parameters in preclinical and phase 1 settings

Obesity is a major public health crisis. Multi-specific peptides have emerged as promising therapeutic strategies for clinical weight loss. Glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are endogenous incretins that regulate weight through their receptors (R). AMG 133 (maridebart cafraglutide) is a bispecific molecule engineered by conjugating a fully human monoclonal anti-human GIPR antagonist antibody to two GLP-1 analogue agonist peptides using amino acid linkers. Here, we confirm the GIPR antagonist and GLP-1R agonist activities in cell-based systems and report the ability of AMG 133 to reduce body weight and improve metabolic markers in male obese mice and cynomolgus monkeys. In a phase 1, randomized, double-blind, placebo-controlled clinical study in participants with obesity (NCT04478708), AMG 133 had an acceptable safety and tolerability profile along with pronounced dose-dependent weight loss. In the multiple ascending dose cohorts, weight loss was maintained for up to 150 days after the last dose. These findings support continued clinical evaluation of AMG 133.

Exploring the efficacy of a Trichoderma asperellum-based seed treatment for controlling Fusarium equiseti in chickpea

BackgroundChickpea plant (Cicer arietinum L.) is an important legume crop that is vulnerable to various fungal pathogens causing significant yield losses. Among them, Fusarium equiseti is a pathogen that has started to raise concern. In contrast, Trichoderma species have been explored for their ability to control such pathogens. In this study, the efficacy of a novel seed treatment formulation was explored for controlling F. equiseti in chickpea plants. The formulation was designated to enhance growth in chickpea plants as well as the ability to protect plants from infection. In addition, this formulation was tested for its effectiveness in maintaining the conidia of the antagonist in the soil after sowing.ResultsApplying the Trichoderma asperellum-based formulation promoted growth, as well as root and aerial biomass. In seedlings derived from treated seeds, the shoot length increased by 36.8%, and the average number of leaves also increased than the control. Following evaluation of disease severity and the foliar alteration index (FAI), a protective effect was noted, as the symptoms of Fusarium were significantly reduced in treated plants than the infected control. Re-isolation from plants infected with F. equiseti was successful in the roots (72.7%), root crown (84.5%), stem (64.4%), and even in petioles (36.1%).ConclusionsDue to both direct antagonist activity and indirect growth promotion ability, the findings suggested that tested formulation can be a sustainable and eco-friendly alternative to chemical fungicides for managing F. equiseti in chickpea seeds.

Siderophore of plant growth promoting rhizobacterium origin reduces reactive oxygen species mediated injury in Solanum spp. caused by fungal pathogens.

The study aims to explore antifungal properties of bacillibactin siderophore produced by the plant growth-promoting rhizobacterium (PGPR) Bacillus subtilis against fungal phytopathogens Alternaria porri and Fusarium equiseti isolated from Solanum lycopersicum and Solanum melongena plants. Alternaria porri and F. equiseti were isolated from infected plants of eggplant and tomato, respectively. A plate assay was employed to assess the effect of bacillibactin against the phytopathogens. The antifungal potential of the PGPR was evaluated by estimation of dry fungal biomass, visualization of cellular deformity using compound and scanning electron microscopy, antioxidative enzyme assay and analysis of membrane damage via using lipid peroxidation. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) analysis was employed to investigate changes in intracellular iron content. The impact of bacillibactin on pathogenesis was evaluated by infecting detached leaves of S. lycopersicum and S. melongena plants with both the pathogens and treating the infected leaves with bacillibactin. Leaves were further investigated for ROS accumulation, extent of necrosis and cell death. Our findings revealed significant damage to the hyphal structure of A. porri and F. equiseti following treatment with bacillibactin. Biomass reduction, elevated antioxidative enzyme levels, and membrane damage further substantiated the inhibitory effects of the siderophore on fungal growth. ICP-AES analysis indicates an increase in intracellular iron content suggesting enhanced iron uptake facilitated by bacillibactin. Moreover, application of 1500µg ml-1 bacillibactin on infected leaves demonstrated a substantial inhibition of ROS accumulation, necrosis, and cell death upon bacillibactin treatment. This study confirms the potent antagonistic activity of bacillibactin against both the phytopathogens A. porri and F. equiseti growth, supporting its potential as a promising biological control agent for fungal plant diseases. Bacillibactin-induced morphological, physiological, and biochemical alterations in the isolated fungi and pathogen-infected leaves highlight the prospects of bacillibactin as an effective and sustainable solution to mitigate economic losses associated with fungal infections in vegetable crops.

Screening of the Antagonistic Activity of Potential Bisphenol A Alternatives toward the Androgen Receptor Using Machine Learning and Molecular Dynamics Simulation.

Over the past few decades, extensive research has indicated that exposure to bisphenol A (BPA) increases the health risks in humans. Toxicological studies have demonstrated that BPA can bind to the androgen receptor (AR), resulting in endocrine-disrupting effects. In recent investigations, many alternatives to BPA have been detected in various environmental media as major pollutants. However, related experimental evaluations of BPA alternatives have not been systematically implemented for the assessment of chemical safety and the effects of structural characteristics on the antagonistic activity of the AR. To promote the green development of BPA alternatives, high-throughput toxicological screening is fundamental for prioritizing chemical tests. Therefore, we proposed a hybrid deep learning architecture that combines molecular descriptors and molecular graphs to predict AR antagonistic activity. Compared to previous models, this hybrid architecture can extract substantial chemical information from various molecular representations to improve the model's generalization ability for BPA alternatives. Our predictions suggest that lignin-derivable bisguaiacols, as alternatives to BPA, are likely to be nonantagonist for AR compared to bisphenol analogues. Additionally, molecular dynamics (MD) simulations identified the dihydrotestosterone-bound pocket, rather than the surface, as the major binding site of bisphenol analogues. The conformational changes of key helix H12 from an agonistic to an antagonistic conformation can be evaluated qualitatively by accelerated MD simulations to explain the underlying mechanism. Overall, our computational study is helpful for toxicological screening of BPA alternatives and the design of environmentally friendly BPA alternatives.

Improvement in Biocontrol Ability of Trichoderma Through Chemical Mutation and Gamma Irradiation for The Control of Soil Borne Pathogens

Biocontrol agent like Trichoderma viride was acclaimed as effective, eco-friendly and cheap, nullifying the ill effect of chemicals, These biocontrol agents are identified to act against on array of important soil borne plant pathogens viz.,Sclerotium rolfsii, Rhizoctonia bataticola and Fusarium oxysporum f. sp. ciceri etc.” Improvement in biocontrol ability of Trichoderma viride through mutation” was carried at Department of Plant Pathology, during 2019-2020. The antagonistic ability of a biocontrol agent was determined by its physiological state so that change in physiological or genetically conditions could alter the antagonism. Hence the genetic modification using mutagenesis offers the potential for producing improved bio-protection is likely to enhance their biocontrol capabilities against soil borne pathogen. Mutagenesis by chemical i.e. Ethyl Methyl Sulphonate (EMS) @ 100, 150, 200 and 250 µl/ml and time interval at 30, 45 and 60 minutes. The influence of gamma irradiation on improving production of antifungal metabolites and biological proficiency of the biocontrol agent against soil borne pathogen. Trichoderma viride were irradiated in different dose of gamma radiation (cobalt-60) @ 0, 20, 30, 40 and 50 k-rad. for induced mutation. Sixteen Trichoderma viride mutants were obtained after chemical mutagenesis and gamma irradiation and tested for their antagonistic activities in vitro. Morphological character of efficient mutants was tested up to six generation to check their stability. Among these, four stable mutants viz., TVME 2b, TVME 2c, TVME 3c and TVGM1 were proved as effective antagonists against Sclerotium rolfsii, Rhizoctonia bataticola and Fusarium oxysporum f.sp. ciceri basis of their maximum bioefficiency. Mutants TVME2b, TVME2c, TVME3c and TVGM1 exhibited the highest inhibition to mycelial growth of Sclerotium rolfsii with an inhibition percentage 64.76, 64.22, 63.08 and 62.93% respectively. Rhizoctonia bataticola was inhibited to the extent of 63.47, 60.87, 61.93 and 61.02% by relative mutants, while Fusarium oxysporum f. sp. ciceri was restricted and recorded 63.50, 62.88, 62.03 and 60.74% respectively. The highest chitinase enzyme units/mg of protein i.e. 0.64, 0.63, 0.63 and 0.62 was exerted in TVME2b, TVME2c, TVME3c and TVGM1 having respectively. However, TVME1c contains 0.37 enzyme units; it showed maximum ability against pathogens. hence present study proved that mutagenesis is the efficient tool for improving bioefficiency of Trichoderma viride, a biocontrol agent.

Enhancing Stability and Efficacy of Trichoderma Bio‐Control Agents Through Layer‐by‐Layer Encapsulation for Sustainable Plant Protection

AbstractAgricultural fungicide pollution poses a significant environmental challenge and causes adverse effects on human health. Therefore, strategies to limit fungicide usage are of paramount importance. Trichoderma fungi, due to their antagonistic activity against various pathogenic fungi, have shown potential as a sustainable alternative to chemical fungicides. However, bio‐control agents like Trichoderma are vulnerable to physical stimuli and show diminished efficacy during prolonged storage. To address these challenges, a mild and scalable encapsulation method for Trichoderma spores is introduced, employing a layer‐by‐layer (LbL) approach using biobased lignin derivatives. It is demonstrated that the LbL encapsulation technique significantly improved spore stability relative to naked spores, even under adverse conditions including extreme temperatures and prolonged exposure to Ultraviolet (UV) irradiation. Notably, encapsulated Trichoderma spores showed enhanced efficacy in cultivating tomato plants compared to naked spores. Additionally, the findings revealed that the in planta efficacy of encapsulated spores is dependent on the specific Trichoderma strain used. This study suggests that Trichoderma spores encapsulated with lignin through the LbL approach, are a promising and sustainable alternative to chemical fungicides with potential for commercialization.

Dual Control of Host Actin Polymerization by a Legionella Effector Pair

Host actin cytoskeleton is often targeted by pathogenic bacteria through the secretion of effectors. Legionella pneumophila virulence relies on the injection of the largest known arsenal of bacterial proteins, over 300 Dot/Icm type 4 secretion system effectors, into the host cytosol. Here, we define the functional interactions between VipA and LegK2, two effectors with antagonistic activities towards actin polymerization that have been proposed to interfere with the endosomal pathway. We confirmed the prominent role of LegK2 effector in Legionella infection, as the deletion of legK2 results in defects in the inhibition of actin polymerization at the Legionella-containing vacuole, as well as in endosomal escape of bacteria and subsequent intracellular replication. More importantly, we observed the restoration of the ΔlegK2 mutant defects, upon deletion of vipA gene, making LegK2/VipA a novel example of effector-effector suppression pair that targets the actin cytoskeleton and whose functional interaction impacts L. pneumophila virulence. We demonstrated that LegK2 and VipA do not modulate each other’s activity in a “metaeffector” relationship. Instead, the antagonistic activities of the LegK2/VipA effector pair would target different substrates, Arp2/3 for LegK2 and G-actin for VipA, to temporally control actin polymerization at the LCV and interfere with phagosome maturation and endosome recycling, thus contributing to the intracellular life cycle of the bacterium. Strikingly, the functional interaction between LegK2 and VipA is consolidated by an evolutionary history that has refined the best effector repertoire for the benefit of L. pneumophila virulence.

Optical Control of Adenosine A2A Receptor Using Istradefylline Photosensitivity.

In recent years, there has been growing interest in the potential therapeutic use of inhibitors of adenosine A2A receptors (A2AR) for the treatment of neurodegenerative diseases and cancer. Nevertheless, the widespread expression of A2AR throughout the body emphasizes the importance of temporally and spatially selective ligands. Photopharmacology is an emerging strategy that utilizes photosensitive ligands to attain high spatiotemporal precision and regulate the function of biomolecules using light. In this study, we combined photochemistry and cellular and in vivo photopharmacology to investigate the light sensitivity of the FDA-approved antagonist istradefylline and its potential use as an A2AR photopharmacological tool. Our findings reveal that istradefylline exhibits rapid trans-to-cis isomerization under near-UV light, and prolonged exposure results in the formation of photocycloaddition products. We demonstrate that exposure to UV light triggers a time-dependent decrease in the antagonistic activity of istradefylline in A2AR-expressing cells and enables real-time optical control of A2AR signaling in living cells and zebrafish. Together, these data demonstrate that istradefylline is a photoinactivatable A2AR antagonist and that this property can be utilized to perform photopharmacological experiments in living cells and animals.

ANTAGONISTIC ACTIVITY OF ENDOPHYTIC FUNGI ISOLATED FROM ALOE VERA LEAVES AGAINST SOME PLANT PATHOGENIC FUNGI

The present study was aimed to test the antagonistic activity of endophytic fungi isolated from Aloe vera leaves against a number of plant-pathogenic fungi. The results showed that the highest antagonistic activity was exerted by Penicillium chermesinum against the pathogenic fungus Rhizoctonia solani, with an inhibition rate of 78.57%. Also, Talaromyces verruculosus and P. chermesinum showed their highest antagonistic activities against pathogenic fungus Fusarium 1 with inhibition rates of 61.79% and 61.53%, respectively, while T. verruculosus showed an inhibition rate of 62.91% against the pathogenic fungus Fusarium 2. Most of the endophytic fungi showed the least percentage of inhibition against Macrophomina phaseolina compared to the rest of the pathogenic fungi. The fungal filtrates showed a concentration-dependent inhibition rate against the plant pathogens, with a range of 0.00-48.13%. The highest inhibitory activity of Aspergillus niger was recorded at a concentration of 60% against Fusarium 2, R. solani, and Fusarium 1, with rates of 48.13, 37.39, and 36.66%, respectively. The results also showed the ineffectiveness of all fungal filtrates against the pathogenic fungus M. phaseolina. Chemical analysis of the filtrates of the endophytic fungi which showed antagonistic activity against pathogenic fungi was also conducted by using GC-MS. The results showed the presence of effective compounds with biological effects, such as Pentadecanoic acid, Oleic Acid, Limonene, cis-Vaccenic acid, Hexanedioic acid, bis(2-ethylhexyl) ester, Cycloheptasiloxane, and tetracamethyl-.

Screening and evaluation of the biocontrol efficacy of a Trichoderma brevicompactum strain and its metabolite trichodermin against banana Fusarium wilt

The banana Fusarium wilt (BFW) caused by Fusarium oxysporum f. sp. cubense tropical race4 (FocTR4) is difficult to control worldwide, which causes a huge economic losse to banana industry. The purpose of this study was to screen Trichoderma strains with antagonistic activity against FocTR4, to isolate and purify the active compound from the fermentation broth, so as to provide important biocontrol strains and active compound resources. In this work, Trichoderma strains were isolated and screened from the rhizosphere soil of crops, and the strains capable of efficiently inhibiting FocTR4 were screened by plate confrontation, and further confirmed by testing inhibition for the conidial germination and mycelial growth of FocTR4. The phylogenetic tree clarified the taxonomic status of the biocontrol strains. Moreover, the active components in the fermentation broth of the strains were separated and purified by column chromatography, the structure of the most active component was analyzed by nuclear magnetic resonance spectroscopy (NMR), the BFW control effect was tested by pot experiments. We obtained a strain JSHA-CD-1003 with antagonistic activity against FocTR4, and the inhibition rate from plate confrontation was 60.6%. The fermentation broth of JSHA-CD-1003 completely inhibited the germination of FocTR4 conidia within 24 hours. The inhibition rate of FocTR4 hyphae growth was 52.6% within 7 d. A phylogenetic tree was constructed based on the ITS and tef1-α gene tandem sequences, and JSHA-CD-1003 was identified as Trichoderma brevicompactum. Purification and NMR identification showed that the single active compound was trichodermin, and the minimum inhibitory concentration (MIC) was 25 μg/mL. Pot experiments showed that the fermentation broth of strain JSHA-CD-1003 was effective against BFW. The control rate of leaf yellowing was 47.4%, and the rate of bulb browning was 52.0%. Therefore, JSHA-CD-1003 effectively inhibited FocTR4 conidial germination and mycelium growth through producing trichodermin, and showed biocontrol effect on banana wilt caused by FocTR4, thus is a potential biocontrol strain.