Inhibition Of Fungal Growth Research Articles

The Efficiency of Fungicides on Fungal Growth Inhibition in Cultured Tissues of Banana (Musa acominata), and Their Effect on Tissues Traits

The goal of this study was to identify fungicides with a broad-spectrum effectiveness and their capacity to inhibit fungal contaminants in banana tissue cultures. Numerous fungi were isolated from tissues of banana cultures of the Grand 9 variety. Aspergillus flavus, Aspergillus niger, Cladosporium oxysporum, Penicillium digitatum, P. expansum, and Penicillium sp. were among the contaminated fungi isolated. These fungi were inhibited successfully using the fungicides Beltanol, Agrisave, and Zoxis. Hoever, Beltanol was outperformed compared with Agrisave and Zoxis fungicides, with an inhibition rate of 100% for concentrations of 0.25, 0.5, and 1 ml/l. Thus, the addition of Beltanol fungicide to the banana culture medium had a positive influence on the fresh and dry weight of the tissues, with the average fresh weight increasing to 2.93 g compared with 2.4 g in the control treatment. Also, the dry weight was increased from to 0.21 g while it was 0.17 g in the control treatment. Additionally, the results demonstrated the enzymatic effectiveness (cellulase enzyme) of isolated fungi without treatment, that showed high effectiveness in P. digitatum fungus with an activity rate reached 2.33 mm. In contrast, C. oxysporum and P. expansum fungi displayed moderate efficiency with activity rates that reached 1.5 and 1.41 mm respectively. On the other hand, A. flavus and A. niger fungi exhibited low efficacy with activity rates of 1.25 and 1.12 mm respectively. Furthermore, the results revealed that P. expansum fungus had a high enzymatic effectiveness index with a rate of 1.85 mm, while C. oxysporum, P. digitatum, and A. flavus fungi had moderate enzymatic effectiveness with rates of 1.46, 1.34, and 1.26, respectively. A. niger fungus had the lowest enzymatic effectiveness with a rate of 1.23. The enzymatic secretion of the isolated fungi was inhibited efficiently via addition of the fungicide Beltanol to these fungi.

2108. In-vitro Activity of Five Novel Anti-Fungal Compounds Against Thirty-Two Strains of Talaromyces marneffei

Abstract Background Talaromyces marneffei (Tm) is a thermally dimorphic fungus causing invasive mycosis in human immunodeficiency virus (HIV) infected patients in Southeast Asia and is a leading cause of AIDS-related deaths in this region with mortality on anti-fungal therapy as high as 30%. The limited options, routes of administration, and toxicity of antifungals with established efficacy against Tm calls for assessment of efficacy for additional antifungals against Tm. Here we evaluate the in-vitro efficacy of 5 novel anti-fungal agents against 32 clinical strains of Tm. The agents tested include ibrexafungerp, two manogepix compounds (APX001A and APX2039), olorofim, and oteseconazole. Methods 32 Tm isolates were cultured from clinical samples from patients in Vietnam and identified as Tm by standard morphological characteristics. Inocula were prepared from these clinical samples in conjunction with CLSI standards and plated onto 96-well microplates. Concentrations for each drug ranged from 0.008 µg/mL to 4 µg/mL. AlamarBlueTM, a resazurin-based cell viability indicator dye, was added to the drug-inoculum solution. Use of this reagent enabled utilization of a microplate fluorescence intensity(FI) reader to objectively identify the designated MIC endpoint of 50% inhibition of growth. Methods (Figure 1). MIC endpoint determination using AlamarBlue indicator dye method. Clinical Tm isolates were thawed and plated on Yeast Peptone Dextrose (YPD) agar and grown for 3-5 days at 37°C. Isolates were then sub-cultured on fresh YPD agar and allowed to grow for 3 days prior to inoculum preparation. Inocula were prepared according to CLSI standards. Following suspension in solution, inocula were diluted in PBS until an optical density (OD) of 0.5 to 0.6 was achieved. Inocula were further diluted in RPMI + MOPS and added to the drug-dilution microplates to achieve a final concentration of 1000-5000 cells/mL. After incubation at 37°C for 24 hours, AlamarBlue was added to all wells. Following incubation for an additional 48 hours, fluorescence intensity (FI) was measured using a microplate reader to determine the MIC endpoint of 50% inhibition of fungal growth. Results Of the drugs tested, olorofim showed the highest activity against the 32 isolates, with MICs consistently ≤ 0.008 µg/mL. This was followed by oteseconazole with MICs between ≤ 0.008 and 0.031 µg/mL APX001A with MICs between 0.031 and 0.25 µg/mL and APX2039 with MICs between 0.25 and 4 µg/mL. Ibrexafungerp had the broadest MIC distribution with MICs between 0.063 and 4 µg/mL. Figure 2/Table 1. MIC Endpoint Distribution. Figure 2 shows a scatter plot of MIC endpoints for each drug. Error bars demonstrate the geometric mean and 95% confidence intervals. Table 1 illustrates the MIC endpoint distribution in a graded heat map format. In addition, the absolute values of the geometric mean (GM), mode, MIC50, and MIC90 are displayed at the right side of the table. Both Figure 2 and Table 1 illustrate high efficacy for olorofim and oteseconazole, with low MIC endpoints consistent across the 32 isolates. The manogepix compounds(APX001A and APX2039) demonstrate surprisingly contrasted performance against Tm, despite the similar chemical structure and identical mechanism of action of the drugs. APX001A had significantly lower MIC endpoints compared to APX2039. Ibrexafungerp had the broadest range of MIC endpoints from 0.063 to 4µg/mL and the highest MIC50 and MIC90 of all the drugs. However, a significant proportion of isolates were highly susceptible to the drug. Conclusion In-vitro activity of the 5 drugs tested against the 32 Tm strains was variable, but all should be considered potential candidates for treating Tm infection. To further evaluate the potential role of each drug in treating Tm infection, the next step should be to evaluate each in in-vivo models. Disclosures All Authors: No reported disclosures

Isolation of starch and protein degrading strain Bacillus subtilis FYZ1-3 from tobacco waste and genomic analysis of its tolerance to nicotine and inhibition of fungal growth.

Aerobic fermentation is an effective technique for the large-scale processing of tobacco waste. However, the specificity of the structure and composition of tobacco-derived organic matter and the toxic alkaloids in the material make it currently difficult to directly use microbial agents. In this study, a functional strain FYZ1-3 was isolated and screened from thermophilic phase samples of tobacco waste composting. This strain could withstand temperatures as high as 80°C and grow normally at 0.6% nicotine content. Furthermore, it had a strong decomposition capacity of tobacco-derived starch and protein, with amylase activity of 122.3 U/mL and protease activity and 52.3 U/mL, respectively. To further understand the mechanism of the metabolic transformation of the target, whole genome sequencing was used and the secondary metabolite gene cluster was predicted. The inhibitory effect of the strain on common tobacco fungi was verified using the plate confrontation and agar column methods. The results showed that the strain FYZ1-3 was Bacillus subtilis, with a genome size of 4.17 Mb and GC content of 43.68%; 4,338 coding genes were predicted. The genome was annotated and analyzed using multiple databases to determine its ability to efficiently degrade starch proteins at the molecular level. Moreover, 14 functional genes related to nicotine metabolism were identified, primarily located on the distinct genomic island of FYZ1-3, giving a speculation for its nicotine tolerance capability on the molecular mechanism. By mining the secondary metabolite gene cluster prediction, we found potential synthetic bacteriocin, antimicrobial peptide, and other gene clusters on its chromosome, which may have certain antibacterial properties. Further experiments confirmed that the FYZ1-3 strain was a potent growth inhibitor of Penicillium chrysogenum, Aspergillus sydowii, A. fumigatus, and Talaromyces funiculosus. The creation and industrial use of the functional strains obtained in this study provide a theoretical basis for its industrial use, where it would be of great significance to improve the utilization rate of tobacco waste.

Larvicidal and Fungicidal Activity of the Leaf Essential Oil of Five Myrtaceae Species.

Myrtaceae is one of the most diverse and abundant botanical families, exhibiting wide diversity in the chemical composition of essential oils (EOs). EOs have various biotechnological applications such as controlling the populations of organisms that negatively impact humans. This study aimed to extract EOs from Myrtaceae species, chemically characterize them, and evaluate their larvicidal and fungicidal effects. EOs were extracted from the leaves of Eugenia brasiliensis, Eugenia uniflora, Psidium cattleyanum, Psidium guajava, and Syzygium cumini by hydrodistillation for 3 h and characterized by chromatographic analysis. Larvaes of Aedes aegypti and colonies of Fusarium oxysporum were subjected to increasing EO concentrations to determine the larvicidal and fungicidal potential. The EOs of Eugenia and Psidium species are primarily composed of sesquiterpenes (>80 %), whereas S. cumini EO is rich in monoterpenes (more than 60 %). The Eugenia species had similar amounts of oxygenated monoterpenes, which may explain their higher larvicidal potential compared to other species, with CL50 of 86.68 and 147.46 PPM, respectively. In addition to these two study species, S. cumini showed a high inhibition of fungal growth, with more than 65 % inhibition. We demonstrated that the actions of five EOs from Myrtaceae with different biological activities are associated with chemical diversity.

GC-MS profiling and antifungal activities of Morinda citrifolia L. leaf extract against fungal pathogens of crown rot disease of banana

The increasing demand for organic agricultural products especially among the elite stimulated the search for safe and alternative means of crown rot disease control. Morinda citrifolia is one of the listed medicinal plants among the Polynesian countries. This study documented the phytochemical profile of M. citrifolia using GC-MS and their antifungal activities against crown rot pathogens. The key phytochemical constituents of the extract were Phytol 2-Hexadecen-1-ol, (Diterpene) (25.96%), Squalene (Triterpene) (15.13%), 1, 3-Propanediol (Polyphenol) (4.68%), Pyran-4-one 4H-, 9 (Flavonoid), and 2H-1-Benzopyran-6-ol (Vitamins) (5.14%), 2-Cyclohexan-1-one, (Phenol) (2.54%). Fungal pathogens; Lasiodiplodia theobromae, Colletotrichum musae, Colletotrichum asianum and Fussarium Longipes isolated from crown rot infected banana fruits during earlier studies were used in this experiment. The poisoned food technique method was adopted in evaluating the inhibitory effect of the leaf extract against the fungal isolates. Results indicated significantly high fungal growth inhibition (P< 0.05) in concentration dependent manner on amended PDA media. 100% pathogen radial growth inhibition in all isolates was recorded at 100 mg/mL concentration. Therefore, findings of this study suggest application of leaf extract of M. citrifolia is a potential safe and alternative control of banana crown rot.

Genome mining conformance to metabolite profile of Bacillus strains to control potato pathogens

Biocontrol agents are safe and effective methods for controlling plant disease pathogens, such as Fusarium solani, which causes dry wilt, and Pectobacterium spp., responsible for potato soft rot disease. Discovering agents that can effectively control both fungal and bacterial pathogens in potatoes has always presented a challenge. Biological controls were investigated using 500 bacterial strains isolated from rhizospheric microbial communities, along with two promising biocontrol strains: Pseudomonas (T17-4 and VUPf5). Bacillus velezensis (Q12 and US1) and Pseudomonas chlororaphis VUPf5 exhibited the highest inhibition of fungal growth and pathogenicity in both laboratory (48%, 48%, 38%) and greenhouse (100%, 85%, 90%) settings. Q12 demonstrated better control against bacterial pathogens in vivo (approximately 50%). Whole-genome sequencing of Q12 and US1 revealed a genome size of approximately 4.1 Mb. Q12 had 4413 gene IDs and 4300 coding sequences, while US1 had 4369 gene IDs and 4255 coding sequences. Q12 exhibited a higher number of genes classified under functional subcategories related to stress response, cell wall, capsule, levansucrase synthesis, and polysaccharide metabolism. Both Q12 and US1 contained eleven secondary metabolite gene clusters as identified by the antiSMASH and RAST servers. Notably, Q12 possessed the antibacterial locillomycin and iturin A gene clusters, which were absent in US1. This genetic information suggests that Q12 may have a more pronounced control over bacterial pathogens compared to US1. Metabolic profiling of the superior strains, as determined by LC/MS/MS, validated our genetic findings. The investigated strains produced compounds such as iturin A, bacillomycin D, surfactin, fengycin, phenazine derivatives, etc. These compounds reduced spore production and caused deformation of the hyphae in F. solani. In contrast, B. velezensis UR1, which lacked the production of surfactin, fengycin, and iturin, did not affect these structures and failed to inhibit the growth of any pathogens. Our findings suggest that locillomycin and iturin A may contribute to the enhanced control of bacterial pectolytic rot by Q12.

Diversity of phyllospheric Actinomycetes in Liliaceae plants and their potential as growth inhibitors of Alternaria porri

Abstract. Wati C, Nawangsih AA, Wahyudi AT, Wiyono S, Munif A. 2023. Diversity of phyllospheric Actinomycetes in Liliaceae plants and their potential as growth inhibitors of Alternaria porri. Biodiversitas 24: 5234-5242. Actinomycetes are microorganisms belonging to a group of Gram-positive bacteria, that have the potential to act as biological control agents against various plant pathogens. Phyllospheric Actinomycetes particularly, can inhibit growth of various microorganisms, such as the fungus Alternaria porri Ell. Cif., which causes purple blotch disease in the shallot plants. These microbes thrive on the surface of leaves, particularly in plants belonging to Liliaceae family. Environmental conditions have been proven to greatly affect their diversity. Present investigation aims to determine diversity of phyllospheric Actinomycetes from Liliaceae plants and their potential to inhibit growth of A. porri. The methods used were to investigate, characterize, and quantify isolates from Liliaceae plants. An antagonistic test was conducted on the isolates to examine the proportion of A. porri fungus growth inhibition. The results showed that plants species Allium fistulosum and A. tuberosum were the most common hosts for phyllospheric actinomycetes. Morphological differences were found in shape, color, elevation, edges, surface, and hyphae size, as well as the type of spore violation. The surface texture of colonies was smooth, rough, powdery, and opaque, usually appearing after 7-12 days of isolation. The isolates also inhibited growth of A. porri, causing the mycelium thins, and a clear zone of inhibition between pathogens and Actinomycetes forms. Isolates BCW9 caused the highest suppression of fungus growth 57.78%. This study is the first experiment to evaluate the diversity of phyllosphere Actinomycetes from Liliaceae plants, which are able to control purple blotch disease caused by A. porri in Indonesia. The phyllospheric Actinomycetes were isolated from the same habitat of A. porri. These investigation show the prospect of phyllospheric Actinomycetes as biocontrol agents against another fungal diseases on leaves of another plants.

Photodynamic inactivation by hypericin-P123 on azole-resistant isolates of the Trichophyton rubrum complex as planktonic cells and biofilm

IntroductionThe Trichophyton rubrum complex comprises the majority of dermatophyte fungi (DM) responsible for chronic cases of onychomycosis, which is treated with oral or topical antifungals. However, owing to antifungal resistance, alternative therapies, such as photodynamic therapy (PDT), are needed. This study investigated the frequency of the T. rubrum species complex in onychomycosis cases in the northwestern region of Paraná state, Brazil, and evaluated the efficacy of (PDT) using P123-encapsulated hypericin (Hyp-P123) on clinical isolates of T. rubrum in the planktonic cell and biofilm forms. Material and methodsThe frequency of the T. rubrum complex in onychomycosis cases from 2017 to 2021 was evaluated through a data survey of records from the Laboratory of Medical Mycology (LEPAC) of the State University of Maringa (UEM). To determine the effect of PDT-Hyp-P123 on planktonic cells of T. rubrum isolates, 1 × 105 conidia/mL were treated with ten different concentrations of Hyp-P123 and then irradiated with 37.8 J/cm2. Antibiofilm activity of PDT-Hyp-P123 was tested against T. rubrum biofilm in the adhesion phase (3 h), evaluated 72 h after irradiation (37.8 J/cm2), and the mature biofilm (72 h), evaluated immediately after irradiation. In this context, three different parameters were evaluated: cell viability, metabolic activity and total biomass. ResultsThe T. rubrum species complex was the most frequently isolated DM in onychomycosis cases (approximately 80 %). A significant reduction in fungal growth was observed for 75 % of the clinical isolates tested with a concentration from 0.19 μmol/L Hyp-P123, and 56.25 % had complete inhibition of fungal growth (fungicidal action); while all isolates were azole-resistant. The biofilm of T. rubrum isolates (TR0022 and TR0870) was inactivated in both the adhesion phase and the mature biofilm. ConclusionPDT-Hyp-P123 had antifungal and antibiofilm activity on T. rubrum, which is an important dermatophyte responsible for onychomycosis cases.

Expression of BmSPI38 tandem multimers in Escherichia coli and its antifungal activity

The aim of this study was to prepare tandem multimeric proteins of BmSPI38, a silkworm protease inhibitor, with better structural homogeneity, higher activity and stronger antifungal ability by protein engineering. The tandem multimeric proteins of BmSPI38 were prepared by prokaryotic expression technology. The effects of tandem multimerization on the structural homogeneity, inhibitory activity and antifungal ability of BmSPI38 were explored by in-gel activity staining of protease inhibitor, protease inhibition assays and fungal growth inhibition experiments. Activity staining showed that the tandem expression based on the peptide flexible linker greatly improved the structural homogeneity of BmSPI38 protein. Protease inhibition experiments showed that the tandem trimerization and tetramerization based on the linker improved the inhibitory ability of BmSPI38 to microbial proteases. Conidial germination assays showed that His6-SPI38L-tetramer had stronger inhibition on conidial germination of Beauveria bassiana than that of His6-SPI38-monomer. Fungal growth inhibition assay showed that the inhibitory ability of BmSPI38 against Saccharomyces cerevisiae and Candida albicans could be enhanced by tandem multimerization. The present study successfully achieved the heterologous active expression of the silkworm protease inhibitor BmSPI38 in Escherichia coli, and confirmed that the structural homogeneity and antifungal ability of BmSPI38 could be enhanced by tandem multimerization. This study provides important theoretical basis and new strategies for cultivating antifungal transgenic silkworm. Moreover, it may promote the exogenous production of BmSPI38 and its application in the medical field.

GC–MS, quantum mechanics calculation and the antifungal activity of river red gum essential oil when applied to four natural textiles

The most important uses of old fabrics include clothing, mummification, and bookbinding. However, because they are predominantly constructed of natural materials, they are particularly susceptible to physical and chemical deterioration brought on by fungi. The treatments that are typically used to preserve old textiles focus on the use of synthetic fungicides, which have the potential to be dangerous for both human health and the environment. Essential oils (EOs), which are safe for the environment and have no negative effects on human health, have been widely advocated as an alternative to conventional antifungals. Four natural fabrics—linen, cotton, wool, and silk—were utilized in the current work. The extracted EO from leaves of river red gum (Eucalyptus camaldulensis Dehnh.) were prepared at 125, 250, and 500 µL/L. Aspergillus flavus, Fusarium culmorum and Aspergillus niger were inoculated separately into the treated four fabrics with the EO at concentrations of 125, 250, and 500 µL/L or the main compounds (spathulenol and eucalyptol) at the concentrations of 6, 12, 25, and 50 µL/L and were then compared to the un-treated samples. GC–MS was used to analyze the EO chemical composition, while visual observations and scanning electron microscopic (SEM) were used to study the fungal growth inhibition. Spathulenol (26.56%), eucalyptol (14.91%), and p-cymene (12.40%) were the principal chemical components found in E. camaldulensis EO by GC–MS. Spathulenol molecule displayed the highest electrostatic potential (ESP) compared with the other primary compound, as calculated by quantum mechanics. In the untreated textile samples, SEM analysis revealed substantial proliferation of hyphae from A. flavus, F. culmorum, and A. niger. The fungal growth was completely inhibited at a concentration of 500 µL/L from the EO. Both eucalyptol and spathulenol completely inhibited the formation of the fungal spores at a concentration of 50 µL/L, although eucalyptol was more effective than spathulenol across the board for all four textiles. The results support E. camaldulensis EO functionalized textiles as an effective active antifungal agent.

Zinc’s impact on the growth and laccase activity of Trametes pubescens and an equilibrium study of zinc adsorption

ABSTRACT Due to the influence of some ions on laccase production by Trametes pubescens, the impact of different concentrations of zinc (Zn) on fungus growth and laccase production was investigated. The removal kinetics and adsorption isotherm of Zn by T. pubescens from an aqueous solution were evaluated. The results demonstrated the growth inhibition of fungus by an increase in Zn concentration. Zn concentrations of 10 and 20 mg L−1 in the medium caused an increase in the growth of fungus. Laccase production reduced at 100 and 200 mg L−1 of Zn. The kinetic parameters of Zn adsorption onto the biomass of fungus from aqueous solutions (containing 200 mg L−1 Zn) obtained by experiments at different contact times. The results indicated a trend of increasing Zn removal by fungus with the contact time, and it was well-described by the Intra-particle diffusion and Elovich models. The maximum removal of Zn was 67.1% at 7200 min, with a maximum sorption capacity of 44.7 mg g−1. The adsorption of Zn was well-fitted to the Freundlich and Langmuir sorption models. This study indicated an impact of a low concentration of Zn to increase laccase production and the feasibility of this fungus to remove Zn from aqueous solutions.

Antifungal activities of leaf extracts from the Capsicum genus

The emergence of microorganisms resistant to antimicrobials has driven the search for new substances aimed at the control and prevention of pathogens. Plant antimicrobial peptides have biotechnological applications in the development of drugs and agricultural inputs for this purpose. The present work aims to evaluate the antifungal activity of extracts containing peptides obtained from the leaves of Capsicum plants. The accessions UENF 1626, 1632 and 1381 and the cultivar Carioquinha were used. The leaves were macerated, and then extraction was performed using a 60% methanol and dichloromethane solution in a 1:1 ratio. The hydromethanolic phase was separated and used for testing after evaporation of methanol. All extracts have a similar electrophoretic profile on tricine gel stained with Coomassie Blue, showing 2 bands of approximately 6.5 and 3.5 kDa. Inhibition of fungal growth with 24 h of culture was performed in liquid culture medium in 96-well plates with reading at 620 nm using extracts with a protein concentration of 200 mg mL-1. The filamentous fungi Fusarium solani, Fusarium lateritium, and Colletotrichum lindemuthianum and the yeasts Candida albicans, Candida buinensis, Candida tropicalis, Saccharomyces cerevisiae, Pichia membranifaciens and Kluyveromyces marxianus were used. The extract with the greatest antifungal potential was the leaves of Capsicum annuum cv. Carioquinha, inhibiting the growth of F. solani by 29%, C. lindemuthianum by 15%, Candida buinensis by 22% and K. marxianus by 24%. Therefore, the extract has peptides with biotechnological potential.

Surfactin inhibits Fusarium graminearum by accumulating intracellular ROS and inducing apoptosis mechanisms.

Fusarium graminearum, a devastating fungal pathogen, is the main pathogen of Fusarium head blight (FHB) in wheat globally; it results in significant yield loss and mycotoxin contamination that severely threatens global wheat production and food safety. However, despite ongoing efforts, controlling this pathogen still remains a major challenge. Surfactin, primarily synthesized by Bacillus sp. via non-ribosomal peptide synthetases, exhibits potent surfactant and antibacterial properties, but its antifungal mechanism has yet to be fully elucidated. We found that the EC50 of surfactin against hyphal growth of F. graminearum was 102.1µg/mL, and control efficacy against wheat FHB under field conditions achieved 86.38% in wheat cultivar Huaimai 40 and 81.60% in wheat cultivar Zhoumai 36, indicating that surfactin has potential antifungal activity against F. graminearum. Accumulated intracellular ROS, decreased mitochondrial membrane potential (MMP), activated metacaspase activity and condensed chromatin, were induced by surfactin in F. graminearum hyphae, suggesting that growth inhibition of fungus is mainly caused by apoptosis-like cell death. Furthermore, accumulated intracellular ROS was evidenced to act as a key mediator of surfactin-induced apoptosis. Broad-spectrum caspase inhibitor Z-VAD-FMK treatment indicated that surfactin induces caspase-independent apoptosis in F. graminearum. Collectively, this study provides evidence that surfactin induces a ROS-mediated mitochondrial apoptosis in F. graminearum hyphae, and may exert its antifungal activity against F. graminearum by activating apoptosis. This study demonstrates the potential of surfactin as an antifungal agent for FHB biocontrol, provides a new perspective on the antifungal mechanism of surfactin against filamentous fungi, and contributes to the application of surfactin-producing microbes in the biocontrol of plant diseases.

Biological and Chemical Characterization of Musa paradisiaca Leachate.

There is a growing demand for molecules of natural origin for biocontrol and biostimulation, given the current trend away from synthetic chemical products. Leachates extracted from plantain stems were obtained after biodegradation of the plant material. To characterize the leachate, quantitative determinations of nitrogen, carbon, phosphorus, and cations (K+, Ca2+, Mg2+, Na+), Q2/4, Q2/6, and Q4/6 absorbance ratios, and metabolomic analysis were carried out. The potential role of plantain leachates as fungicide, elicitor of plant defense, and/or plant biostimulant was evaluated by agar well diffusion method, phenotypic, molecular, and imaging approaches. The plant extracts induced a slight inhibition of fungal growth of an aggressive strain of Colletotrichum gloeosporioides, which causes anthracnose. Organic compounds such as cinnamic, ellagic, quinic, and fulvic acids and indole alkaloid such as ellipticine, along with some minerals such as potassium, calcium, and phosphorus, may be responsible for the inhibition of fungal growth. In addition, jasmonic, benzoic, and salicylic acids, which are known to play a role in plant defense and as biostimulants in tomato, were detected in leachate extract. Indeed, foliar application of banana leachate induced overexpression of LOXD, PPOD, and Worky70-80 genes, which are involved in phenylpropanoid metabolism, jasmonic acid biosynthesis, and salicylic acid metabolism, respectively. Leachate also activated root growth in tomato seedlings. However, the main impact of the leachate was observed on mature plants, where it caused a reduction in leaf area and fresh weight, the remodeling of stem cell wall glycopolymers, and an increase in the expression of proline dehydrogenase.

Dimethylpolysulfides production as the major mechanism behind wheat fungal pathogen biocontrol, by Arthrobacter and Microbacterium actinomycetes.

Volatile organic compounds (VOCs) produced by plant-associated microorganisms could serve as natural biocontrol compounds. In this work, we investigate the potential of wheat rhizosphere Microbacterium and Arthrobacter actinomycetes to inhibit the growth of major wheat phytopathogenic fungi, Fusarium graminearum and Zymoseptoria tritici via production of antifungal VOCs. A correlative analysis between fungal-growth inhibition versus bacterial volatilomic profiles identified four dimethylpolysulfide (DMPS) VOCs as the main active compounds behind their biocontrol potential. Subsequent inhibition assays reveal that DMTriS (dimethyltrisulfide) exhibits the strongest inhibition effects, then dimethyldisulfide (DMDiS). Further investigation focuses on the mechanisms behind F. graminearum-growth inhibition by the most active strain Microbacterium JM188 in dual culture. Surprisingly, nine interaction-induced VOCs, including two fungal sesquiterpenes, were exclusively detected in dual cultures, suggesting a complex interplay between microbial VOC production and sensing. More importantly, all JM188 VOCs, including antifungal DMPS, were less abundant in dual cultures, suggesting an uptake of bacterial VOCs by the fungus. Quantification of pure DMPS after confrontation with F. graminearum confirmed complete and partial uptake by the fungus of DMTriS and DMDiS VOCs, respectively, suggesting a potential link between the fungal uptake level of bacterial VOCs and their toxicity. Finally, we demonstrated that F. graminearum growth inhibition leads to a complete depletion of DON (deoxynivalenol) carcinogenic mycotoxins, highlighting a significant modulation of fungal metabolism. Collectively, these results pinpoint DMPS as broad-range fungal-inhibiting VOCs produced by rhizosphere Microbacterium and Arthrobacter, and emphasize the extensive VOC-mediated interplay between bacterial biocontrol agents and fungal pathogens.IMPORTANCEAs the management of wheat fungal diseases becomes increasingly challenging, the use of bacterial agents with biocontrol potential against the two major wheat phytopathogens, Fusarium graminearum and Zymoseptoria tritici, may prove to be an interesting alternative to conventional pest management. Here, we have shown that dimethylpolysulfide volatiles are ubiquitously and predominantly produced by wheat-associated Microbacterium and Arthrobacter actinomycetes, displaying antifungal activity against both pathogens. By limiting pathogen growth and DON virulence factor production, the use of such DMPS-producing strains as soil biocontrol inoculants could limit the supply of pathogen inocula in soil and plant residues, providing an attractive alternative to dimethyldisulfide fumigant, which has many non-targeted toxicities. Notably, this study demonstrates the importance of bacterial volatile organic compound uptake by inhibited F. graminearum, providing new insights for the study of volatiles-mediated toxicity mechanisms within bacteria-fungus signaling crosstalk.

Antifungal activity test of nanosilver combination with lip balm cosmetic preparation

Nanosilveris is a silver-based material with nanometer particle sizes (1-100 nm) predicted to be antifungal or an alternative to preservatives in lip balm preparations that are biocompatible. The nanosilver synthesis process in this study used the bottom-up method by adding sodium citrate as a reducing agent and stabilizer. This study aimed to determine the characteristics of the results of 20 ppm nanosilver synthesis using a UV-Vis and TEM spectrophotometer and to determine the antifungal activity of nanosilver in lip balm cosmetic preparations. Variations in adding 20 ppm nanosilver into lip balm preparations are 5%, 10%, and 15%. The results of characterization using a UV-Vis spectrophotometer, namely 20 ppm nanosilver, were quite stable in storage for 2 months, and the results of characterization using TEM also showed that the formed nanosilver remained stable with a nanometer size range ranging from 11.42 nm to 43.95 nm. The antifungal activity test was carried out using the Direct Microscopic Count (DMC) method by counting directly under a microscope. Based on the data obtained, it shows that the antifungal activity of the combination of nanosilver and lip balm preparations is almost equivalent to the antifungal activity of parabens. It has produced lip balm preparations with nanosilver. This is indicated by the value of the inhibition rate (%). The inhibition of fungal growth produced by lip balm preparations with parabens is almost the same as the inhibition rate (%) produced by lip balm preparations with nanosilver. The inhibition rate of lip balm preparations with parabens was 89.11%. In comparison, the inhibition rate of lip balm preparations with a nanosilver concentration of 15% was 82.31%, so it can be concluded that nanosilver has good antifungal activity and is biocompatible so that nanosilver can be used as an alternative to paraben preservatives.

Sustainable Lignin-Based Nano Hybrid Biomaterials with High-Performance Antifungal Activity.

Aspergillus flavus (A. flavus) and Aspergillus niger (A. niger) mainly spread through airborne fungal spores. An effective control to impede the dissemination of the spores of Aspergillus in the air affecting the environment and food was carried out. This study focuses on the sustainable rice husk-extracted lignin, nanolignin, lignin/n-lignin capped silver nanoparticles used for fungal growth inhibition. These biomaterials inhibit the growth of fungi by altering the permeability of cell membranes and influencing intracellular biosynthesis. The antifungal indexes for A. flavus and A. niger on day 5 at a concentration of 2000 μg/100 μL are 50.8 and 43.6%, respectively. The results demonstrate that the hybrid biomaterials effectively prevent the growth or generation of fungal spores. The findings of this research hold significant implications for future investigations focused on mitigating the dissemination of Aspergillus during the cultivation of agricultural products or in the process of assuring agricultural product management, such as peanuts and onions.

Antifungal activity of Lysinibacillus macroides against toxigenic Aspergillus flavus and Fusarium proliferatum and analysis of its mycotoxin minimization potential

BackgroundToxigenic fungi (Aspergillus and Fusarium) and their metabolites represent the major cause of corn and corn-based products contamination and consequently lead to severe economic and health issues.AimOur current study aimed to investigate the efficacy of using L. macroides Bac6 as a biological control agent against the toxigenic fungi; A. flavus f10 and F. proliferatum f30 and their mycotoxins.ResultsThe results illustrated that A. flavus f10 produced the aflatoxins AFB1 and AFG2 with concentrations of 21.239 and 13.593 ppb, respectively. While F. proliferatum f30 produced fumonisin B1 (9600 ppb). Furthermore, L. macroides showed a high potential for inhibition of toxigenic fungal growth using a dual culture method. F. proliferatum f30 and A. flavus f10 were found to be inhibited by a percentage of 80 and 62.5%, respectively. The results were confirmed using the scanning electron microscope. The antagonistic bacteria, L. macroides, showed chitinase productivity and activity of 26.45 U/L and 0.12 U/mL/min, respectively, which illustrates its potential application as a biocontrol agent. The GC-MS analysis revealed an abundance of Pyrrolo[1,2-a] pyrazine-1,4-dione, Hexahydro in the bacterial supernatant that exhibited antifungal characteristics. L. macroides had a significant reduction of AFB1 and AFG2 produced by A. flavus f10, recording 99.25% and 99% inhibition, respectively. It also showed strong inhibition of fumonisin B1 (90% inhibition) produced by F. proliferatum f30. Conclusion: Thus, the current study is a prospective study evaluating for the first time the potential impact of L. macroides Bac6 against the toxigenic fungi and their toxins.

Native rhizobacteria suppresses spot blotch disease, improves growth and yield of wheat under salt–affected soils

The simultaneous occurrence of biotic and abiotic stresses affects the performance of the crops in salt–affected agroecologies. The plant–microbe interaction with effective rhizobacteria can effectively manage these stresses. This study characterized the biocontrol, plant growth promotion, and responsiveness of rhizobacteria in wheat under salt-affected soils. Out of the 184 rhizobacteria isolates, the 20 isolates showed 41–72% growth inhibition of fungal phytopathogens of seedling blight of wheat (Fusarium sp), head blight of wheat (Fusarium oxysporum), onion molds (Penicillium sp and Aspergillus sp), root rot of wheat (Rhizoctonia solani), ear rot of corn (Aspergillus sp.) and spot blotch of wheat (Bipolaris sorokininana). The potent three rhizobacterial isolates identified as close neighbours of Bacillus amyloliquefaciens strain TA124, B. subtilis strain SB67 and B. subtilis strain BJ171 caused 65.5–71.1% growth inhibition of B. sorokiniana. The extracellular organic acid, siderophore, and chitinase enzymes played a significant role in rhizobacterial performance for fungal growth inhibition; and P and Zn solubilization in growth media. The foliar spray of bioformulation aids 15–20% reduction in the B. sorokiniana disease severity. The rhizobacterial responsiveness to the dual inoculation through seed treatment and foliar spray was 12.6–51, 15.8–46.3, and 13.2–148.1% for grain yield, P uptake, and disease suppression, respectively. The changes caused by rhizobacterial bioformulation in soil (Olsen's–P and microbial biomass carbon) and plant (proline, malondialdehyde, peroxidase, and Na+/K+ratio) explained 85% variability in the yield, P nutrition, and disease severity. Therefore, native rhizobacteria with biocontrol and plant growth-promoting capabilities can be an effective option for managing multiple stresses of crops in salt–affected agroecologies.

Synthesis and Antiphytopathogenic Activity of Novel Oxazolidine-2,4-diones Bearing Phenoxypyridine Moiety.

In the present study, we conducted optimization of pyramoxadone and synthesized a series of novel oxazolidinediones. Antifungal assays showed that these compounds exhibited moderate to excellent antifungal activity against various pathogens. Further SAR analysis revealed that the introduction of substituents to the benzene ring of the phenoxy group or the inclusion of bulky groups, such as tert-butyl, on the aniline moiety, had a detrimental effect on the activity. However, the inclusion of fluorine atoms in the aniline moiety significantly enhanced the antifungal efficacy. Notably, compound 2-4 displayed significantly higher activity compared to both pyramoxadone and famoxadone against R. solani, B. cinerea, S. sclerotiorum, and P. oryzae, where it demonstrated EC50 values of 1.78, 2.47, 2.33, and 2.23 μg/mL, respectively. Furthermore, compound 2-4 exhibited potent protective and curative effects against the tomato gray mold in vivo. A mechanistic investigation revealed that compound 2-4 significantly impacted the mycelial morphology, inhibited spore germination, and impeded mycelial respiration, ultimately leading to the inhibition of pathogenic fungus growth. These findings indicate that compound 2-4 has the potential to serve as a cyt bc1 inhibitor and should be further investigated for development.