Fungal Inhibition Research Articles

Unveiling the Potential of Bacillus safensis Y246 for Enhanced Suppression of Rhizoctonia solani.

Rhizoctonia solani is a significant pathogen affecting various crops, including tobacco. In this study, a bacterial strain, namely Y246, was isolated from the soil of healthy plants and exhibited high antifungal activity. Based on morphological identification and DNA sequencing, this bacterial strain was identified as Bacillus safensis. The aim of this investigation was to explore the antifungal potential of strain Y246, to test the antifungal stability of Y246 by adjusting different cultivation conditions, and to utilize gas chromatography-mass spectrometry (GC-MS) to predict the volatile compounds related to antifungal activity in Y246. In vitro assays demonstrated that strain Y246 exhibited a high fungal inhibition rate of 76.3%. The fermentation broth and suspension of strain Y246 inhibited the mycelial growth of R. solani by 66.59% and 63.75%, respectively. Interestingly, treatment with volatile compounds derived from the fermentation broth of strain Y246 resulted in abnormal mycelial growth of R. solani. Scanning electron microscopy analysis revealed bent and deformed mycelium structures with a rough surface. Furthermore, the stability of antifungal activity of the fermentation broth of strain Y246 was assessed. Changes in temperature, pH value, and UV irradiation time had minimal impact on the antifungal activity, indicating the stability of the antifungal activity of strain Y246. A GC-MS analysis of the volatile organic compounds (VOCs) produced by strain Y246 identified a total of 34 compounds with inhibitory effects against different fungi. Notably, the strain demonstrated broad-spectrum activity, exhibiting varying degrees of inhibition against seven pathogens (Alternaria alternata, Phomopsis. sp., Gloeosporium musarum, Dwiroopa punicae, Colletotrichum karstii, Botryosphaeria auasmontanum, and Botrytis cinerea). In our extensive experiments, strain Y246 not only exhibited strong inhibition against R. solani but also demonstrated remarkable inhibitory effects on A. alternata-induced tobacco brown spot and kiwifruit black spot, with impressive inhibition rates of 62.96% and 46.23%, respectively. Overall, these findings highlight the significant antifungal activity of B. safensis Y246 against R. solani. In addition, Y246 has an excellent antifungal stability, with an inhibition rate > 30% under different treatments (temperature, pH, UV). The results showed that the VOCs of strain Y246 had a strong inhibitory effect on the colony growth of R. solani, and the volatile substances produced by strain Y246 had an inhibitory effect on R. solani at rate of 70.19%. Based on these results, we can conclude that Y246 inhibits the normal growth of R. solani. These findings can provide valuable insights for developing sustainable agricultural strategies.

Evaluation of Bacillus sp. strains for biological control of gummy stem blight, Didymella bryoniae (Auersw.) in watermelon (Citrullus lanatus)

The gummy stem blight caused by Didymella bryoniae (Auersw.) is a major and destructive disease of watermelon in Vietnam. Bacillus species have been used to control plant diseases as biological control agents. This study was carried out at the Department of Crop Production and Plant Protection, Phu Yen province, Vietnam during 2020 – 2021 to determine fungal inhibition of D. bryoniae DB-03 in in vitro and disease suppression of gummy stem blight under greenhouse conditions by Bacillus sp. strains namely S1A1, S1F3, S13E3, S18F11, and S20D12, which were isolated from stem-base of groundnut in central Vietnam. Results revealed that, all the tested strains of Bacillus sp. showed good inhibitory effect on the hyphal growth of D. bryoniae strain DB-03 in potato dextrose broth. Among the strains, Bacillus sp. S20F12 had highest inhibition of the mycelia growth of D. bryoniae strain DB-03 with an antagonistic efficiency of 60.7% at 10 days after fungal inoculation. Bacillus sp. reduced gummy stem blight under greenhouse conditions. At 21 days after fungal inoculation, disease incidences were low in the plants treated with Bacillus sp. S18F11 and S20D12 by 60.0% and 63.3%, respectively. The results would contribute to the knowledge of antagonistic activities of the Bacillus to optimize the biological control programme against D. bryoniae.

Management of sunflower charcoal-rot and maize late-wilt diseases using the aqueous extract of vermicompost (vermitea) and environmental-safe biochar derivative (wood vinegar)

In Egypt, sunflower charcoal-rot caused by Macrophomina phaseolina and maize late-wilt caused by Magnaporthiopsis maydis are the most prevalent, and can lead to huge yield losses of both crops under epidemic conditions. In this study, the potential use of vermitea and wood vinegar for management of both diseases was investigated. Data revealed that, among the 17 bacterial strains obtained from vermitea, three strains named VCB-2, VCB-7 and VCB-11 were chosen for having the greatest in vitro inhibitory effect against M. phaseolina and M. maydis, with fungal inhibition values of 54.2; 61.7, 65.2; 74.0 and 57.1; 87.0% against both pathogens, respectively. These strains were identified as Bacillus amyloliquefaciens, Serratia marcescens and Bacillus velezensis, respectively. Wood vinegar significantly reduced the colony diameter of M. phaseolina and M. maydis in in vitro trials conducted on potato dextrose agar medium amended with the desired concentrations of 0.5, 1.0, 1.5, 2.0, and 2.5%. The efficiency increased with increasing wood vinegar concentration, and 2.0% was the most effective (100% suppression). Data from greenhouse experiments showed that the application of vermitea or wood vinegar tended to decrease the incidence (% dead plants) of sunflower charcoal-rot (by 61.1 and 66.7%) and maize late-wilt (by 70.6%). These treatments had positive impacts on the plant growth parameters, photosynthetic pigments and antioxidative enzymes of sunflower and maize plants. Data from field experiments showed that the application of vermitea or wood vinegar decreased the incidence of charcoal-rot (by 72.8 and 72.0%) and late-wilt (by 88.7 and 87.0%) as well as increased the production sunflower and maize plants.

Anti-MRSA and Biological Activities of Propolis Concentrations Loaded to Chitosan Nanoemulsion for Pharmaceutics Applications.

Propolis is a naturally occurring substance with beneficial properties; bees produce it from various plant sources, and it is an anti-inflammatory and therapeutic resinous substance. This study aimed to enhance the biological features of propolis extract by loading it onto active film. Firstly, extraction was performed using three solvent systems, and their total phenolic, flavonoid, and antioxidant activity was measured. Propolis ethanol extract (EEP) was evaluated for phenolic fraction content and then chosen to prepare a chitosan-loaded emulsion with several concentrations. The antibacterial, anti-mycotic, and anti-mycotoxigenic properties of the extract and nanoemulsion were assessed. PPE's cytotoxicity and nanoemulsion were evaluated using brine shrimp and cell line assays. Results indicate higher phenolic (322.57 ± 4.28 mg GAE/g DW), flavonoid (257.64 ± 5.27 mg QE/g DW), and antioxidant activity of the EEP. The phenolic fraction is distinguished by 18 phenolic acids with high p-hydroxybenzoic content (171.75 ± 1.64 µg/g) and 12 flavonoid compounds with high pinocembrin and quercetin content (695.91 ± 1.76 and 532.35 ± 1.88 µg/g, respectively). Phenolic acid derivatives (3,4-Dihydroxybenzaldehyde, 3,4-Dihydroxyphenol acetate, and di-methoxy cinnamic) are also found. Concentrations of 50, 100, 150, and 200 ng EEP loaded on chitosan nanoemulsion reflect significant antibacterial activity against pathogenic bacteria, particularly methicillin-resistant Staphylococcus aureus (MRSA) and toxigenic fungi, particularly Fusarium. Among the four EEP-loaded concentrations, the nanoemulsion with 150 ng showed outstanding features. Using a simulated medium, 150 and 200 ng of EEP-loaded chitosan nanoemulsion concentrations can stop zearalenone production in Fusarium media with complete fungi inhibition. Also, it reduced aflatoxins production in Aspergillus media, with fungal inhibition (up to 47.18%). These results recommended the EEP-chitosan application for pharmaceutics and medical use as a comprehensive wound healing agent.

Anti-fungal bioactive terpenoids in the bioenergy crop switchgrass (Panicum virgatum) may contribute to ecotype-specific microbiome composition

Plant derived bioactive small molecules have attracted attention of scientists across fundamental and applied scientific disciplines. We seek to understand the influence of these phytochemicals on rhizosphere and root-associated fungi. We hypothesize that – consistent with accumulating evidence that switchgrass genotype impacts microbiome assembly – differential terpenoid accumulation contributes to switchgrass ecotype-specific microbiome composition. An initial in vitro Petri plate-based disc diffusion screen of 18 switchgrass root derived fungal isolates revealed differential responses to upland- and lowland-isolated metabolites. To identify specific fungal growth-modulating metabolites, we tested fractions from root extracts on three ecologically important fungal isolates – Linnemania elongata, Trichoderma sp. and Fusarium sp. Saponins and diterpenoids were identified as the most prominent antifungal metabolites. Finally, analysis of liquid chromatography-purified terpenoids revealed fungal inhibition structure – activity relationships (SAR). Saponin antifungal activity was primarily determined by the number of sugar moieties – saponins glycosylated at a single core position were inhibitory whereas saponins glycosylated at two core positions were inactive. Saponin core hydroxylation and acetylation were also associated with reduced activity. Diterpenoid activity required the presence of an intact furan ring for strong fungal growth inhibition. These results inform future breeding and biotechnology strategies for crop protection with reduced pesticide application.

Fungal inhibition by lactic acid bacteria (LAB) is modulated in vitro by cocoa fermentation-related conditions: towards a biocontrol of fungi in processing cocoa

Fungal growth impair strongly the quality of processed cocoa, leading to low crops value for farmers and manufacturers. The antifungal activity of lactic acid bacteria (LAB) from fermenting cocoa was analyzed and the conditions of fungal inhibition were evaluated. Fungi were isolated from stored fermented and dried cocoa beans on sabouraud plate medium. The results showed that, LAB strongly inhibit fungi isolated from fermented cocoa beans notably Mucors and Aspergilli, with Lactobacillus plantarum inducing the stronger inhibition whereas Leuconostoc mesenteroides produced a weaker inhibition. Acids production assayed by HPLC was found to be not related to antifungal activity, since LAB strains producing strong antifungal activity were not necessarly the best acid producers. Maximum fungal inhibition occured at 35 °C in Lactobacillus plantarum and Leuconostoc mesenteroides but also at 30 °C in Lactobacllus casei. Likewise, a narrow acidic pH range (3.0-4.0) allowed full expression of fungal inhibtion in LAB analyzed that decreased progressively toward pH 7.0 and failed at alkalin pH. However, sucrose even at high content (8%) was found to have no effect on antifungal activity of LAB, but its bioconversion product glucose and fructose decreased this activity when concentrations were set at 6 et 2 %, respectively. All together, the results suggest that, LAB may effectively exert fungal inhibition in a narrow timing of cocoa fermentation, with pulp contained sugars as metabolic regulators of this inhibition. These results may contribute to a better management of LAB as starter culture for an efficient inhibition of fungal growth and prevention of cocoa contamination from mycotoxins.
 Key Words : Antifungal activity ; lactic acid bacteria ; cocoa fermentation ; inhibition variation; pH and temperature ; sugars content.

A Re-Purposing Strategy: Sub-Lethal Concentrations of an Eicosanoid Derived from the Omega-3-Polyunsaturated Fatty Acid Resolvin D1 Affect Dual Species Biofilms.

The fungal species Candida parapsilosis and the bacterial species Staphylococcus aureus may be responsible for hospital-acquired infections in patients undergoing invasive medical interventions or surgical procedures and often coinfect critically ill patients in complicating polymicrobial biofilms. The efficacy of the re-purposing therapy has recently been reported as an alternative to be used. PUFAs (polyunsaturated fatty acids) may be used alone or in combination with currently available traditional antimicrobials to prevent and manage various infections overcoming antimicrobial resistance. The objectives of the study were to evaluate the effects of Resolvin D1 (RvD1) as an antimicrobial on S. aureus and C. parapsilosis, as well as the activity against the mixed biofilm of the same two species. Microdilution assays and time-kill growth curves revealed bacterial and fungal inhibition at minimum concentration values between 5 and 10 μg mL-1. In single-species structures, an inhibition of 55% and 42% was reported for S. aureus and C. parapsilosis, respectively. Moreover, RvD1 demonstrated an eradication capacity of 60% and 80% for single- and mixed-species biofilms, respectively. In association with the inhibition activity, a downregulation of genes involved in biofilm formation as well as ROS accumulation was observed. Eradication capability was confirmed also on mature mixed biofilm grown on silicone platelets as shown by scanning electron microscopy (SEM). In conclusion, RvD1 was efficient against mono and polymicrobial biofilms in vitro, being a promising alternative for the treatment of mixed bacterial/fungal infections.

Detection of actinobacteria from sediment soil: Exploration of metabolites as fungal plant pathogen inhibitors and plant growth promoters

The rhizosphere is an area with dense microbial activity. Actinobacteria are one among the rhizomicroflora inhabiting in the plant rhizosphere by protecting plants from pathogens by producing secondary metabolites, as plant growth promoters and by producing hydrolytic enzymes. But in the modern era of agriculture, the outrageous use of chemical fertilizers in the agriculture fields is causing major environmental pollution and the agricultural soil is losing its texture and fertility. So, in the present study, we aimed to isolate and screen indigenous actinobacterial strains which are capable of producing antifungal metabolites, plant growth promoting ability and hydrolytic enzymes. A total of 23 isolates of actinobacteria have been isolated. Among all the other actinobacterial isolates, Streptomyces sp. DRPG-15, which was isolated from the sediment soil of the Tamankal River, revealed a noticeable antagonistic activity against Macrophomina phaseolina for Sorghum and Sclerotium rolfsii for Chickpeas respectively. 16S rRNA sequence analysis showed that the Streptomyces sp. DRPG-15 exhibited 100% homology with Streptomyces enissocaesilis DRPG-15 OP985046. All 23 isolates were screened for the production of indole acetic acid, hydrogen cyanide, ammonia production and nitrate reduction and were also screened for various hydrolytic enzymes like Caseinase, Protease, Cellulase, Amylase, Chitinase, Pectinase, Gelatinase, L-asparaginase and Streptomyces sp. DRPG-15 was the only isolate that showed positive results for antagonistic activity, plant growth-promoting ability and enzymatic activity. The entire study indicates that the selected strain of Streptomyces sp. DRPG-15 is implying its possible utilization as a natural bioinoculant for sustainable agriculture.

Characterization of tea (Camellia sinensis L.) flower extract and insights into its antifungal susceptibilities of Aspergillus flavus

BackgroundTea (Camellia sinensis L.) flowers will compete with tea leaves in nutrition and are abandoned as an undesirable by-product. In this study, the biological efficacy of tea flowers was investigated. Further exploration of its antifungal activity was explained.MethodsTea flowers harvested from China were characterized in term of component, antioxidant ability, tyrosinase inhibition, and antifungal ability. Chemical compounds of tea flowers were analyzed by LC-MS. Disinfectant compounds were identified in tea flowers, and 2-ketobutyric acid exhibited antifungal activity against Aspergillus flavusCCTCC AF 2023038. The antifungal mechanism of 2-ketobutyric acid was further investigated by RNA-seq.ResultsWater-soluble tea flower extracts (TFEs) exhibited free radical scavenging activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2, 2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)(ABTS) as well as a high ferric-reducing ability. However, no inhibition of tyrosinase activity was observed. In the antifungal test, 6.4 mg/mL TFE reached 71.5% antifungal rate and the electrical conductivity of the culture broth increased with increasing concentration of TFE, implying that it damaged the fungal cell membrane by the TFE. Several disinfectants were identified in TFE by LC-MS, and 2-ketobutyric acid was also confirmed to be capable of fungal inhibition. Propidium iodide (PI) staining indicated that 2-ketobutyric acid caused damage to the cell membrane. RNA-seq analysis revealed that 3,808 differentially expressed genes (DEGs) were found in A. flavus CCTCC AF 2023038 treated by 2-ketobutyric acid, and more than 1,000 DEGs involved in the integral and intrinsic component of membrane were affected. Moreover, 2-ketobutyric acid downregulated aflatoxin biosynthesis genes and decreased the aflatoxin production.ConclusionsOverall, TFE exhibited excellent antioxidant ability and fungal inhibition against A. flavus CCTCC AF 2023038 due to its abundant disinfectant compounds. As a recognized food additive, 2-ketobutyric acid is safe to use in the food industry and can be utilized as the basis for the research and development of strong fungicides.

Inhibition of chitin deacetylases to attenuate plant fungal diseases

Phytopathogenic fungi secrete chitin deacetylase (CDA) to escape the host’s immunological defense during infection. Here, we showed that the deacetylation activity of CDA toward chitin is essential for fungal virulence. Five crystal structures of two representative and phylogenetically distant phytopathogenic fungal CDAs, VdPDA1 from Verticillium dahliae and Pst_13661 from Puccinia striiformis f. sp. tritici, were obtained in ligand-free and inhibitor-bound forms. These structures suggested that both CDAs have an identical substrate-binding pocket and an Asp-His-His triad for coordinating a transition metal ion. Based on the structural identities, four compounds with a benzohydroxamic acid (BHA) moiety were obtained as phytopathogenic fungal CDA inhibitors. BHA exhibited high effectiveness in attenuating fungal diseases in wheat, soybean, and cotton. Our findings revealed that phytopathogenic fungal CDAs share common structural features, and provided BHA as a lead compound for the design of CDA inhibitors aimed at attenuating crop fungal diseases.

Agricultural fungicidal effect of floral extracts of Bauhinia variegata, B. forficata and B. purpurea

Bauhinia is a botanical genus widely distributed in parts of Asia and South America. The plant bears beautiful and aromatic flowers that add ornamental beauty to parks and gardens, in addition to being used in medicine and ayurverda. This study aimed to evaluate the floral ethanolic extract of B. variegata, B. forficata and B. purpurea in fungal inhibition against Sclerotinia sclerotiorum, Colletotrichum gloeosporioides and Colletotrichum acutatum. Flowers were harvested in 2021 and 2022. The floral ethanolic extract was produced by the static maceration method. The antifungal activity was performed by the agar diffusion method at different extract s;concentrations. Bauhinia floral extracts showed a potential fungicidal effect on fungal species evaluated in particular for Sclerotinia sclerotiorum, followed by Colletotrichum gloeosporioides and Colletotrichum acutatum.

Spo0A-dependent antifungal activity of a plant growth promoting rhizobacteria Bacillus subtilis strain UD1022 against the dollar spot pathogen (Clarireedia jacksonii)

Dollar spot is an economically important foliar disease of turfgrass caused by Clarireedia spp. Increased use of chemical fungicides for disease management has possible negative effects on the environment and human health. The quest for eco-friendly alternatives to fungicides is driving the development of new biological strategies for managing dollar spot. In the present study, an analysis of antifungal activity of the plant growth promoting rhizobacteria (PGPR) Bacillus subtilis strain UD1022 (hereafter UD1022) and plant health products (PHPs) (Acibenzolar-S-methyl, kelp extract, fosetyl-Al, and trinexapac-ethyl) against Clarireedia jacksonii for control of the turfgrass fungal disease dollar spot was conducted. In vitro assays revealed that UD1022 has significant inhibitory effects against the mycelial growth of C. jacksonii. Of all the treatments, wild type UD1022 and a non-ribosomal peptide mutant (sfp¯) showed potential antagonism against C. jacksonii with inhibition rate of 17.2 % and 18.4%, respectively. Interestingly a Bacillus-derived broad antifungal compound (surfactin) and PHPs showed no direct antagonistic activity against dollar spot pathogen and were statistically like the untreated control. All the mutants of UD1022 except spo0A¯ showed varying but significant inhibition of the fungal pathogen suggesting that spo0A gene may be directly involved in the antagonism against C. jacksonii. Bacterial volatile compounds (BVCs) of UD1022 may not be involved in antagonism as no fungal inhibition was observed in the indirect assay using split petri plates. Filter sterilized cell free lysate (CFL) as well as heat treated CFL of UD1022 bacterial culture did not show any fungal inhibition indicating a primary role of live bacterial cells and not bacterial-derived or secreted compounds in fungal growth inhibition. The results indicate UD1022 to possess the potential to be extended for the biocontrol of dollar spot of turfgrass.

Phytochemical prospecting and biological activities of the floral extract from [Impatiens walleriana (Hook.)] (Balsaminaceae)

Impatiens walleriana is a plant species that presents diversity and variety of colors among flowers. This plant species has wide distribution and is easily cultivable throughout the world including natural gardens, greenhouses and parks. This study aims at evaluating the floral extracts of I. walleriana in terms of their qualitative phytochemical constitution and antifungal activities on Sclerotinia sclerotiorum, Colletotrichum gloeosporioides and Colletotrichum acutatum, as well as on the reduction of DPPH free radical and on the inhibition of acetylcholinesterase (AChE). Flowers were collected from two cultivars Pink and White of I. walleriana and the extract produced by maceration. The phytochemical qualitative assay was carried out using different reagents for determination by precipitation or colorimetric alteration. The antifungal test was carried out in Petri dishes with different concentrations of floral extract on S. sclerotiorum, C. gloeosporioides and C. acutatum. The DPPH reduction assay was performed by percentage and as standard antioxidant ascorbic acid. The acetylcholinesterase inhibition test was performed in percentage using Electrophorus electricus. Positive results were observed for phenolics, anthocyanins, organic acids, alkaloids, catechins, tannins, carboxylic acids, hemolytic saponins and sesquiterpene lactones. Fungal inhibition effect was better observed for cv. Pink with 10-26%, 6% and between 9-11% on S. sclerotiorum, C. gloeosporioides and C. acutatum, respectively. The DPPH reduction activity showed satisfactory results for cv. Pink 49% followed by cv. White 41%. And for inhibition of AChE cv. Pink with 30% and cv. White with 27%. The floral extracts of Impatiens walleriana show good results for the biological activities tested, especially for cv. Pink.

Enhancing antifungal properties of chitosan by attaching isatin-piperazine-sulfonyl-acetamide pendant groups via novel imidamide linkage

World health organization listed fungi as priority pathogens in 2022 to counter their adverse effects on human well-being. The use of antimicrobial biopolymers is a sustainable alternative to toxic antifungal agents. In this study, we explore chitosan as an antifungal agent by grafting a novel compound N-(4-((4-((isatinyl)methyl)piperazin-1-yl)sulfonyl)phenyl) acetamide (IS). The acetimidamide linkage of IS to chitosan herein was confirmed by 13C NMR and is a new branch in chitosan pendant group chemistry. The modified chitosan films (ISCH) were studied using thermal, tensile, and spectroscopic methods. The ISCH derivatives strongly inhibit fungal pathogens of agricultural and human importance, namely Fusarium solani, Colletotrichum gloeosporioides, Myrothecium verrucaria, Penicillium oxalicum, and Candida albicans. ISCH80 showed an IC50 value of 0.85 μg/ml against M. verrucaria and ISCH100 with IC50 of 1.55 μg/ml is comparable to the commercial antifungal IC50 values of Triadiamenol (3.6 μg/ml) and Trifloxystrobin (3 μg/ml). Interestingly, the ISCH series remained non-toxic up to 2000 μg/ml against L929 mouse fibroblast cells. The ISCH series showed long-standing antifungal action, superior to our lowest observed antifungal IC50 values of plain chitosan and IS at 12.09 μg/ml and 3.14 μg/ml, respectively. ISCH films are thus suitable for fungal inhibition in an agricultural setting or food preservation.

Synergistic inhibition effect of ultraviolet irradiation and benzalkonium chloride on the corrosion of 316L stainless steel caused by Aspergillus terreus

Microbiologically influenced corrosion (MIC) is a key factor that damages engineering materials in marine environments. One of the major concerns in this regard is the corrosion protection of stainless steel (SS) caused against fungal attacks. This study investigated the effect of ultraviolet (UV) irradiation and benzalkonium chloride (BKC) on the corrosion of 316L stainless steel (316L SS) induced by marine Aspergillus terreus in 3.5 wt% NaCl solution. This was accomplished by employing microstructural characterisations and electrochemical analysis to analyse the synergistic inhibition behaviour of the two methods. The results indicated that while UV and BKC demonstrated individual abilities to suppress the biological activity of A. terreus, their inhibitory effects were not significant. The combination of UV light and BKC was found to cause a further decline in the biological activity of A. terreus. The analysis revealed that the combination of BKC and UV significantly decreased the sessile cell counts of A. terreus by more than three orders of magnitude. The fungal corrosion inhibition effect of individual application of UV light or BKC did not yield satisfactory results owing to the low intensity of UV and low concentration of BKC. Furthermore, the corrosion inhibition of UV and BKC occurred mainly during the early stages. The corrosion rate of the 316L SS declined rapidly when the combination of UV light and BKC were used, indicating that UV light and BKC exert a good synergistic inhibitory effect on the corrosion of the 316L SS caused by A. terreus. Therefore, the results suggest that the combination of UV light and BKC can be an effective approach to control the MIC of 316L SS in marine environments.

The potential role of plant secondary metabolites on antifungal and immunomodulatory effect.

With the widespread use of antibiotic drugs worldwide and the global increase in the number of immunodeficient patients, fungal infections have become a serious threat to global public health security. Moreover, the evolution of fungal resistance to existing antifungal drugs is on the rise. To address these issues, the development of new antifungal drugs or fungal inhibitors needs to be targeted urgently. Plant secondary metabolites are characterized by a wide variety of chemical structures, low price, high availability, high antimicrobial activity, and few side effects. Therefore, plant secondary metabolites may be important resources for the identification and development of novel antifungal drugs. However, there are few studies to summarize those contents. In this review, the antifungal modes of action of plant secondary metabolites toward different types of fungi and fungal infections are covered, as well as highlighting immunomodulatory effects on the human body. This review of the literature should lay the foundation for research into new antifungal drugs and the discovery of new targets. KEY POINTS: • Immunocompromised patients who are infected the drug-resistant fungi are increasing. • Plant secondary metabolites toward various fungal targets are covered. • Plant secondary metabolites with immunomodulatory effect are verified in vivo.

EEF2 diphthamide modification restrains spurious frameshifting to maintain translational fidelity.

Diphthamide (DPH), a conserved amino acid modification on eukaryotic translation elongation factor eEF2, is synthesized via a complex, multi-enzyme pathway. While DPH is non-essential for cell viability and its function has not been resolved, diphtheria and other bacterial toxins ADP-ribosylate DPH to inhibit translation. Characterizing Saccharomyces cerevisiae mutants that lack DPH or show synthetic growth defects in the absence of DPH, we show that loss of DPH increases resistance to the fungal translation inhibitor sordarin and increases -1 ribosomal frameshifting at non-programmed sites during normal translation elongation and at viral programmed frameshifting sites. Ribosome profiling of yeast and mammalian cells lacking DPH reveals increased ribosomal drop-off during elongation, and removal of out-of-frame stop codons restores ribosomal processivity on the ultralong yeast MDN1 mRNA. Finally, we show that ADP-ribosylation of DPH impairs the productive binding of eEF2 to elongating ribosomes. Our results reveal that loss of DPH impairs the fidelity of translocation during translation elongation resulting in increased rates of ribosomal frameshifting throughout elongation and leading to premature termination at out-of-frame stop codons. We propose that the costly, yet non-essential, DPH modification has been conserved through evolution to maintain translational fidelity despite being a target for inactivation by bacterial toxins.

Bacterial and fungal inhibitor interacted impacting growth of invasive Triadica sebifera and soil N2O emissions

Plant invasions affect biodiversity and seriously endanger the stability of ecosystems. Invasive plants show strong adaptability and growth advantages but are influenced by various factors. Soil bacteria and fungi are critical to plant growth and are important factors affecting plant invasions. Plant invasions also affect soil N2O emissions, but the effects of invasive plants from different population origins on N2O emissions and their microbial mechanisms are not clear. In this experiment, we grew Triadica sebifera from native (China) and invasive (USA) populations with or without bacterial (streptomycin) and/or fungal (iprodione) inhibitors in a factorial experiment in which we measured plant growth and soil N2O emissions of T. sebifera. Plants from invasive populations had higher leaf masses than those from native populations when soil bacteria were not inhibited (with or without fungal inhibition) which might reflect that they are more dependent on soil bacteria. Cumulative N2O emissions were higher for soils with invasive T. sebifera than those with a plant from a native population. Bacterial inhibitor application reduced cumulative N2O emissions but reductions were larger with application of the fungal inhibitor either alone or in combination with the bacterial inhibitor. This suggests that fungi play a strong role in plant performance and soil N2O emissions. Therefore, it is important to further understand the effects of soil microorganisms on the growth of T. sebifera and soil N2O emissions to provide a more comprehensive scientific basis for understanding the causes and consequences of plant invasions.

Bacterial structural genomics target enabled by a recently discovered potent fungal acetyl-CoA synthetase inhibitor.

The compound ethyl-adenosyl monophosphate ester (ethyl-AMP) has been shown to effectively inhibit acetyl-CoA synthetase (ACS) enzymes and to facilitate the crystallization of fungal ACS enzymes in various contexts. In thisstudy, the addition of ethyl-AMP to a bacterial ACS from Legionella pneumophila resulted in the determination of a co-crystal structure of this previously elusive structural genomics target. The dual functionality of ethyl-AMP in both inhibiting ACS enzymes and promoting crystallization establishes its significance as a valuable resource for advancing structural investigations of this class of proteins.

Effect of Neem Extract on Fungus Inhibition in Toona ciliata M. Roem.

The increasing human population and continuous demands of timber and its derived products like composite wood, has created a significant pressure on the demand for high quality timber from forests. This, ultimately has resulted in pressurising the natural forests and increase in the unvailibility of the production of high quality or durable timber from the forests. The one way to neutralize this pressure on the forests is to modify the other non durable wood species having undesirable properties like hygroscopicity, anisotropy, dimensional instability and biodegradability. Treatment with neem extracts as a biopreservative proves to be very efficient to protect the wood from bacterial or fungal rots. In the present study, wood specimens of Toona ciliata M. Roem. were treated with neem leaf and seed extracts for 72 hours in concentrations of 0.25, 0.5, 1, 1.5 and 2% (w/v), and analyzed for fungal growth and inhibition on dry weight basis using Polyporous rubidus. The fungal growth was maximum in untreated (control) samples whereas, minimum growth was observed in the neem leaf and seed extracts with 2.00% concentration. This method comes to be one of the most eco-friendly processes of wood preservation and helps in utilization of Toon wood in more effective and sustainable way. Also, the minimal release of harmful chemicals in the environment, helps to widen the industrial applications of Toona ciliata wood and make its acceptance to the society with ease.