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Pseudomonas fluorescens FD6 has been shown to possess many beneficial traits involved in the biocontrol of fungal plant pathogens, such as Botrytis cinerea and Monilinia fructicola . Vfr (virulence factor regulator) a highly conserved global regulator of gram-negative bacteria, such as the human pathogen Pseudomonas aeruginosa , is required for the expression of many important virulence traits. The role of Vfr in the regulation of biocontrol traits, such as the production of antibiotics to control fungal pathogens by antagonistic bacteria, has not been elucidated. This study investigated the effect of a vfr mutant derived from P. fluorescens FD6 to better understand the regulation of some important biocontrol traits associated with the bacterium. Biochemical studies indicated that the production of the antibiotics 2,4-diacetylphloroglucinol, pyrrolnitrin and pyoluteorin, was markedly enhanced in the vfr mutant. The vfr mutation also increased biofilm production, swimming motility and the expression of exopolysaccharide-associated gene ( pelA , pslA and pslB ) transcripts, but reduced protease production. Wheat rhizosphere and root tip colonization by the vfr mutant was higher than that by the wild type at 7 and 21 days after inoculation. These findings demonstrate that Vfr modulates the expression of several key traits and the production of important antibiotics involved in the biocontrol potential of P. fluorescens FD6. [ABSTRACT FROM AUTHOR]

In agriculture, biocontrol agents have been emerged as safe alternative to chemical pesticides where Streptomyces spp. and their metabolites constitute a great potential for their exploration as potent agents for controlling various fungal phytopathogens. The present study reports an antifungal compound purified from Streptomyces hydrogenans strain DH16, a soil isolate, using silica gel chromatography and semi preparative HPLC. The compound was characterized using various spectroscopic techniques (IR, ¹H and 13C NMR) and named 10-(2,2-dimethyl-cyclohexyl)-6,9-dihydroxy-4,9-dimethyl-dec-2-enoic acid methyl ester (SH2). Compound (SH2) showed significant inhibitory activity against fungal phytopathogens and resulted in severe morphological aberrations in their structure. Minimal inhibitory and minimal fungicidal concentrations of the compound ranged from 6.25 to 25 µg/ml and 25 to 50 µg/ml, respectively. In vivo evaluation of the compound showed strong control efficacy against Alternaria brassicicola, a seed borne pathogen, on radish seeds. In comparison to mancozeb and carbendazim, the compound was more effective in controlling damping off disease. Additionally, it promoted plant growth with increased rate of seed germination, and displayed no phytotoxicity. The compound retained its antifungal activity after its exposure to temperature of 100°C and sunlight for 1 h. Furthermore, the compound (SH2) when tested for its biosafety was found to be non-cytotoxic, and non-mutagenic against Salmonella typhimurium TA98 and TA100 strains. This compound from S. hydrogenans strain DH16 has not been reported earlier, so this new compound can be developed as an ideal safe and superior biofungicide for the control of various fungal plant diseases. [ABSTRACT FROM AUTHOR]

Effects of anthocyanins from purple sweet potato (APSP) against the fungal growth of Geotrichum candidum and Candida albicans were assessed. Response surface methodology was applied for optimization of proportions of sodium benzoate, potassium sorbate, and APSP. Optimum concentrations against G. candidum were 0.300 mg/mL of sodium benzoate, 0.290mg/mL of potassium sorbate, and 13.9mg/mL of APSP. Optimum concentrations against C. albicans were 0.380 mg/mL of sodium benzoate, 0.240 mg/mL of potassium sorbate, and 3.56 mg/mL of APSP. APSP exhibited enhanced antifungal properties in the presence of food preservatives. [ABSTRACT FROM AUTHOR]

Conventional antifungal treatments against Candida albicans in the oral cavity often result in increased cytotoxicity. The goal of this study was to determine the potential of starch Pickering emulsion as a delivery vehicle for an antifungal natural phenolic compound such as thymol in simulated saliva fluid (SSF) compared to amphotericin B. An oil-in-water (o/w) emulsion was stabilized using starch particles. Physical stability of the emulsion and disruption induced by α-amylase activity in SSF was evaluated. Encapsulated thymol in o/w emulsion was compared to encapsulated amphotericin B for antifungal activity against C. albicans in suspension using emulsions or zone inhibition assay on agar plates using emulsions dispersed in alginate films. Results showed that the emulsions were stable for at least three weeks. Digestion of the emulsion by α-amylase led to coalescence of emulsion droplets. The antifungal activity of thymol and amphotericin B in emulsion formulation was enhanced upon incubation with α-amylase. Results from the zone inhibition assay demonstrated efficacy of the emulsions dispersed in alginate films. Interestingly, addition of α-amylase to the alginate films resulted in a decreased inhibitory effect. Overall, this study showed that starch Pickering emulsions have a potential to deliver hydrophobic antifungal compounds to treat oral candidiasis. [ABSTRACT FROM AUTHOR]

Here we report for the first time the isolation of butyl 2,3-dihydroxybenzoate (B2,3DB) from the novel antagonistic bacterium Paenibacillus elgii HOA73 and its activity against Fusarium oxysporum f.sp. lycopersici (FOL). In this study, the bacterial strain P. elgii HOA73 was isolated from soil and identified via 16S rRNA gene sequence analysis. The isolate demonstrated significant antagonism towards several plant pathogens including FOL. Our results showed the bacterial culture filtrate of P. elgii HOA73 to be highly active, inhibiting 86.1% of the growth of FOL at 50% concentration. Similarly, the bacterial crude extract of P. elgii HOA73 at 2 mg significantly inhibited FOL growth by 72.5%. An antifungal compound was purified from the bacterial crude extract of P. elgii HOA73 through different chromatographic techniques and was identified as butyl 2,3-dihydroxybenzoate (B2,3DB) based on nuclear magnetic resonance and liquid chromatography-mass spectrometry analyses. B2,3DB displayed potent antifungal properties, inhibiting FOL growth by 83.2% when used at 0.6 mg. The minimum inhibitory concentration of B2,3DB to inhibit any visible mycelial growth of FOL was 32 μml-1. All FOL conidia displayed an absence of germination or degradation when treated with 32 μg ml-1 B2,3DB after 8 or 24 h, respectively. Therefore, our results clearly demonstrated B2,3DB, as well as P. elgii HOA73, as potential biological control agents for the management of FOL. [ABSTRACT FROM AUTHOR]

In the present study, Lactobacillus pentosus, L. plantarum, L. fermentum, L. brevis, L. paraplantarum, L. buchneri, and L. acidipiscis, which are strains capable of producing antifungal metabolites against food-spoilage fungi, were isolated and identified based on 16S rRNA gene sequencing from different traditional pickles. L. brevis P68 exhibited significant antifungal activity, and it's in vitro antioxidant and probiotic properties were investigated. The antifungal compound was characterized based on C nuclear magnetic resonance (NMR), H NMR, infrared, and mass spectral data. The minimum inhibitory concentration (MIC) of the compounds was assessed using the broth micro-dilution technique. The MIC of the compounds against Penicillium chrysogenum and P. roqueforti was 2.5 mg mL and that against Gibberella moniliformis and Aspergillus clavatus was 5.0 mg mL. In addition, the HO (1.0 mM) hydroxyl radical, and DPPH scavenging activity inhibition rates were 32.76 and 48.63 %, respectively, and the activities toward the glutathione peroxidase and superoxide dismutase enzymes were high. This strain tolerated low pH and bile salt, exhibited bile salt hydrolase and extracellular enzyme activities, and was sensitive to common antibiotics with high hydrophobicity. This study revealed that the antifungal, antioxidant, and probiotic properties of L. brevis P68 confirmed its application to the food industry. [ABSTRACT FROM AUTHOR]

Pseudomonas aeruginosa PNA1, isolated from the rhizosphere of chickpea in India, suppressed Fusarium wilt of chickpea, caused by Fusarium oxysporum f. sp. ciceris, and Pythium damping-off of bean, caused by Pythium splendens. When grown in culture, PNA1 produced the phenazine antibiotics phenazine-1-carboxylic acid and oxychloraphine, and inhibited mycelial growth of F. oxysporum f. sp. ciceris, P. splendens, and certain other phytopathogenic fungi. Two mutants (FM29 and FM13) deficient in phenazine production were obtained following transposon mutagenesis of PNA1. The transposon in the genome of FM29 was localized to phnA, which is thought to encode a subunit of anthranilate synthase II involved in the phenazine biosynthesis. The FM13 mutation was complemented by trpC, which encodes indole glycerol phosphate synthase in the tryptophan biosynthesis pathway; consequently, FM13 could not grow on a minimal medium in the absence of tryptophan. Neither FM29 nor FM13 suppressed Fusarium wilt of chickpea to the level achieved by the wild-type strain, indicating that phenazine production contributed to the biocontrol of this disease by P. aeruginosa PNA1. FM29 was also less effective than the phenazine-producing parental strain in biological control of Pythium damping-off of bean, but FM13 was as effective as the parental strain in suppressing this disease. Anthranilate, an intermediate in the tryptophan biosynthesis pathway, suppressed mycelial growth of Pythium spp. in culture and Pythium damping-off of bean and lettuce. Anthranilate, excreted by FM13 as a consequence of the trpC mutation, may have contributed to the suppression of Pythium damping-off by the mutant.

Background Green and blue mold decay, caused by Penicillium digitatum and P. italicum, respectively, are important postharvest diseases of citrus. Biocontrol by microbes is an alternative to synthetic fungicide application. In this study, the antagonistic yeast strain Kloeckera apiculata 34-9 was used to investigate the action mechanisms involved in the biocontrol of postharvest diseases. Results An antifungal substance, 2-phenylethanol (PEA), was isolated from K. apiculata and demonstrated to have antimicrobial activity against selected phytopathogenic fungi. Experiments on P. italicum cells identified the mitochondria and the nucleus as particularly sensitive to inhibition. Regulation of P. italicum gene expression was investigated using RNA-Seq. PEA up-regulated genes involved with the peroxisome, regulation of autophagy, phosphatidylinositol signaling system, protein processing in endoplasmic reticulum, fatty acid metabolism, and inhibited ribosome, RNA polymerase, DNA replication, amino acid biosynthesis, aminoacyl-tRNA biosynthesis and cell cycle. Inhibitory responses revealed by RNA-Seq suggest that PEA might compete for attachment on the active site of phenylalanyltRNA synthetase (PheRS). Conclusion This study provided new insight on the mode of action of biocontrol yeast agents in controlling postharvest pathogenic fungi. [ABSTRACT FROM AUTHOR]

This study aimed to describe the diversity of antifungal lactic acid bacteria (LAB) in popular traditional Korean fermented food. A total of 22 LAB strains was selected and subjected to a monophasic identical approach using 16S rRNA gene sequence analysis. Antifungal LAB associated with fermented food was identified as Lactobacillus plantarum (9), Lactobacillus graminis (5), Lactobacillus pentosus (4), Lactobacillus sakei (2), Lactobacillus paraplantarum (1), and Leuconostoc mesenteroides subsp. mesenteroides (1). Novel Lactobacillus plantarum strain K46 exhibited comparatively better antifungal activity against several spoilage fungi, and was deposited in the Korean Collection for Type Cultures (KACC91758P). Antifungal substances from the spent medium in which K46 was cultivated were extracted with ethyl acetate. Antifungal activity was assessed using the broth micro dilution technique. Compounds were characterized based on infrared, C nuclear magnetic resonance (NMR), and H NMR spectral data. The minimum inhibitory concentration (MIC) of the compounds against Aspergillus clavatus, Aspergillus oryzae, Penicillium chrysogenum and Penicillium roqueforti was 2.5 mg/mL and that against Aspergillus fumigatus, Aspergillus niger, Curvularia lunata and Gibberella moniliformis was 5.0 mg/mL. K46 was able to survive gastrointestinal conditions simulating the stomach and the duodenum passage with the highest percentage of hydrophobicity. In addition, its resistance to hydrogen peroxide and highest hydroxyl radical and 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activities, with inhibition rates of 43.53 % and 56.88 %, respectively, were to its advantage. An antimicrobial susceptibility pattern was an intrinsic feature of this strain, thus consumption does not represent a health risk to humans. The results showed the potential of K46 strain as an antifungal, probiotic and antioxidant culture, and hence it was determined to be suitable for application in functional foods. [ABSTRACT FROM AUTHOR]

Streptomyces philanthi RM-1-138, isolated from the rhizosphere soil of chili pepper in southern Thailand, was investigated for its antagonistic activity against phytopathogenic fungi. In dual culture on glucose yeast-malt extract (GYM) agar plates, this strain suppressed the mycelial growth of all seven plant pathogenic fungi tested (Rhizoctonia solani PTRRC-9, Pyricularia grisea PTRRC-18, Colletotrichum gloeosporioides NBCRSR-3, Colletotrichum capcisi NBCRSR-15, Ganoderma boninense NBCRSR-26, Fusarium fujikuroi PTRRC-16 and Bipolaris oryzae PTRRC-36) with an 82.2–89.2% inhibition and that was most pronounced on R. solani PTRRC-9. Heat treatment of the culture filtrate from growing R. solani PTRRC-9 at 40 °C, 60 °C, 80 °C, and 100 °C for 30 min and 121 °C for 15 min had no negative effect on the inhibitory activity against R. solani PTRRC-9 tested on both solid and liquid culture. The effective dose (>80% inhibition) of culture filtrate in liquid culture was at 5.0% (v/v) while it was at 10% (v/v) on the solid medium. This effectiveness was similar to those of the four chemical fungicides tested. The effect of S. philanthi RM-1-138 against R. solani PTRRC-9 was investigated using SEM and TEM. The compounds produced by S. philanthi RM-1-138 induced alterations to the cell-wall structure of R. solani PTRRC-9, that resulted in the loss of cytoplasm materials by partial lysis. The greenhouse experiment revealed that using either the culture filtrate or the autoclaved culture filtrate from S. philanthi RM-1-138 effectively suppressed rice sheath blight disease by up to 65.6 and 60.8%, respectively. [ABSTRACT FROM AUTHOR]

Aims The purpose of this study was to isolate, identify and characterize an antifungal compound from Lactobacillus plantarum KCC-10 from forage silage with potential beneficial properties. Methods and Results The 16S rRNA gene-based phylogenetic affiliation was determined using bioinformatic tools and identified as Lactobacillus sp. KCC-10 with 100% sequence similarity to L. plantarum. The antifungal substances were extracted with ethyl acetate from spent medium in which Lactobacillus sp. KCC-10 was cultivated. Antifungal activity was assessed using the broth microdilution technique. The compounds were obtained by eluting the crude extract with various concentrations of solvents followed by chromatographic purification. Based on the infrared, 13 C nuclear magnetic resonance ( NMR) and 1 H NMR spectral data, the compound was identified as a phenolic-related antibiotic. The minimum inhibitory concentration of the compound against Aspergillus clavatus, A. oryzae, Botrytis elliptica and Scytalidium vaccinii was 2·5 mg ml−1 and that against A. fumigatus, A. niger and S. fusca was 5·0 mg ml−1, respectively. In addition, Lactobacillus sp. KCC-10 was highly sensitive towards oxgall (0·3%) but grew well in the presence of sodium taurocholate (0·3%). An antimicrobial susceptibility pattern was an intrinsic feature of this strain; thus, consumption does not represent a health risk to humans or animals. Conclusion Novel L. plantarum KCC-10 with antifungal and potential probiotic properties was characterized for use in animal food. Significance and Impact of the Study This study revealed that L. plantarum KCC-10 exhibited good antifungal activity similar to that of probiotic Lactobacillus strains. [ABSTRACT FROM AUTHOR]

Abstract: The morbidity, mortality and economic burden associated with fungal infections, together with the emergence of fungal strains resistant to current antimicrobial agents, necessitate broadening our understanding of fungal pathogenesis and discovering new agents to treat these infections. Using invertebrate hosts, especially the nematode Caenorhabditis elegans and the model insects Drosophila melanogaster and Galleria mellonella, could help achieve these goals. The evolutionary conservation of several aspects of the innate immune response between invertebrates and mammals makes the use of these simple hosts an effective and fast screening method for identifying fungal virulence factors and testing potential antifungal compounds. The purpose of this review is to compare several model hosts that have been used in experimental mycology to-date and to describe their different characteristics and contribution to the study of fungal virulence and the detection of compounds with antifungal properties. This article is part of a Special Issue entitled: Animal Models of Disease. [Copyright &y& Elsevier]

Bacillus subtilis strains are known to produce a vast array of antimicrobial compounds. However, some compounds remain to be identified. Disk assays performed in vitro with Bacillus subtilis CU12 showed a significant reduction in mycelial growth of Alternaria solani, Botrytis cinerea, Fusarium sambucinum, and Pythium sulcatum. Crude B. subtilis culture filtrates were subsequently extracted with ethyl acetate and butanol. A bioassay guided purification procedure revealed the presence of one major antifungal compound in the butanol extract. Purification of the compound was performed using a reverse-phase C18 solid phase extraction (SPE) cartridge and flash column chromatography. NMR data showed that the main antimicrobial compound was a cyclic dimer of 3-hydroxypropionaldehyde (HPA). This study demonstrated the antimicrobial activity of B. subtilis strain CU12 against phytopathogenic microorganisms is mediated at least in part by the production of HPA. It also suggests that this B. subtilis strain could be effective at controlling pathogens through protection of its ecological niche by antibiosis. [ABSTRACT FROM AUTHOR]

Abstract: The aims of this study were to investigate the antifungal activity as a bioactive property of dihydrodehydrodiconiferyl alcohol 9′-O-β-d-glucoside (DDDC9G) and the mode of action(s) involved in its effect. Antifungal susceptibility testing showed that DDDC9G possessed potent antifungal activities toward various fungal strains with almost no hemolytic effect. To understand the antifungal mechanism(s) of DDDC9G, we conducted the following experiments in this study using Candida albicans. Fluorescence experiments using the probes, 1, 6-diphenyl-1, 3, 5-hexatriene (DPH) and propidium iodide suggested that DDDC9G perturbed the fungal plasma membrane. Consecutively, the analysis of the transmembrane electrical potential (ΔΨ) with 3, 3′-dipropylthiadicarbocyanine iodide [DiSC3(5)] and bis-(1, 3-dibutylbarbituric acid) trimethine oxonol [DiBAC4(3)] indicated that DDDC9G induced membrane-depolarization. Furthermore, model membrane studies were performed with rhodamine-labeled giant unilamellar vesicles (GUVs), calcein encapsulating large unilamellar vesicles (LUVs), and FITC-dextran (FD) loaded LUVs. These results demonstrated that the antifungal effects of DDDC9G upon the fungal plasma membrane were through the formation of pores with the radii between 0.74nm and 1.4nm. Finally, in three dimensional (3D) flow cytometric contour plots, a reduced cell size was observed as a result of osmolarity changes from DDDC9G-induced structural and functional membrane damages. Therefore, the present study suggests that DDDC9G exerts its antifungal effect by damaging the membrane through pore formation in the fungal plasma membrane. [Copyright &y& Elsevier]

Galbonolides A and B are antifungal compounds, which are produced by Streptomyces galbus. A multimodular polyketide synthase (PKS) was predicted to catalyze their biosynthesis, and a methoxymalonyl-acyl carrier protein (methoxymalonyl-ACP) was expected to be involved in the biosynthesis of galbonolide A. Cloning of a methoxymalonyl-ACP biosynthesis locus ( galGHIJK) and the flanking regions has revealed that the locus is colocalized with β-ketoacyl synthase (KAS)-related genes ( orf3, 4, and 5), but separated from any multimodular PKS gene cluster in S. galbus. A galI-disruption mutant (SK- galI- 5) is unable to produce galbonolide A, but can synthesize galbonolide B, indicating that galGHIJK is involved in the biosynthesis of galbonolide A. A disruption mutant of orf4 is severely impaired in the production of both galbonolides A and B. These results indicate that galGHIJK and the KAS genes are involved in the biosynthesis of galbonolides, although they are not colocalized with a multimodular PKS gene cluster. We further propose that a single galbonolide PKS generates two discrete structures, galbonolides A and B, by alternatively incorporating methoxymalonate and methylmalonate, respectively. [ABSTRACT FROM AUTHOR]

Abstract: Histidinol dehydrogenase, the product of the HisD gene, mediates the final step in the histidine biosynthetic pathway. This enzyme has captured attention for drug discovery studies in past few years. Recently, our group cloned and expressed Geotrichum candidum histidinol dehydrogenase and successful screening of substrate analog inhibitors of histidinol dehydrogenase led to some antifungal compounds with IC50 values in micromolar range. In this study, we have done docking analysis of these antifungal agents in G. candidum. Two new compounds were designed based on the docking results and these compounds turned out to be potent inhibitors of G. candidum histidinol dehydrogenase, showing IC50 values as low as 3.17μM. [Copyright &y& Elsevier]

A dihydropyridine derivative, diethyl 4-(4-methoxyphenyl)-2,6-dimethyl-1,4-dihydropyridin-3,5-dicarboxylate (2e), having potent antifungal activity against pathogenic species of Aspergillus was investigated for its possible molecular mechanism of action. The SDS-PAGE coupled with nano-high-performance liquid chromatography–tandem mass spectrometry was used directly to assess both absolute abundance and differential expression of proteins in the secretory phases of Aspergillus fumigatus under the influence of 2e. It was observed that the compound inhibited the expression of two proteins of 60.99 and 79.77 kDa. Both of these secretory proteins that were inhibited by 2e, were analysed further by matrix assisted laser desorption ionization time-of-flight mass spectrometry. The 60.99- and 79.77-kDa proteins were identified as probable retroelement pol polyprotein and elongation factor G respectively. These targeted proteins could be the products of potentially virulence-related genes of A. fumigatus which may unravel the mode of action of 2e and pathobiology of A. fumigatus. [ABSTRACT FROM AUTHOR]

Information on microbial genome sequences is a powerful resource for accessing natural products with significant activities. We herein report the unveiling of lucensomycin production by Streptomyces achromogenes subsp. streptozoticus NBRC14001 based on the genome sequence of the strain. The genome sequence of strain NBRC14001 revealed the presence of a type I polyketide synthase gene cluster with similarities to a biosynthetic gene cluster for natamycin, which is a polyene macrolide antibiotic that exhibits antifungal activity. Therefore, we investigated whether strain NBRC14001 produces antifungal compound(s) and revealed that an extract from the strain inhibited the growth of Candida albicans. A HPLC analysis of a purified compound exhibiting antifungal activity against C. albicans showed that the compound differed from natamycin. Based on HR-ESI-MS spectrometry and a PubChem database search, the compound was predicted to be lucensomycin, which is a tetraene macrolide antibiotic, and this prediction was supported by the results of a MS/MS analysis. Furthermore, the type I polyketide synthase gene cluster in strain NBRC14001 corresponded well to lucesomycin biosynthetic gene cluster (lcm) in S. cyanogenus, which was very recently reported. Therefore, we concluded that the antifungal compound produced by strain NBRC14001 is lucensomycin. [ABSTRACT FROM AUTHOR]

The potential of anthranilate in the control of Pythium-induced damping-off in horticultural crops was investigated under gnotobiotic conditions. Mutational studies of P. aeruginosa PNA1 led us to identify anthranilate as an antifungal compound active against Pythium species. Anthranilate inhibited growth of the Pythium species in vitro and a 50% growth inhibition was observed at the concentration of 30 μg/ml of anthranilate in GCY medium. The addition of anthranilate at 50 μg/g of potting mix protected lettuce, tomato and beans in vivo against Pythium-induced damping-off. In view of rapid germination of Pythium sporangia in response to seed or root exudates and followed by immediate infection, the use of anthranilate in the suppression of damping-off was investigated. [ABSTRACT FROM AUTHOR]

Abstract: Pseudomonas sp. M18 can suppress certain soil-borne phytopathogenic fungi by producing two antibiotics, pyoluteorin (Plt) and phenazine-1-carboxylic acid (PCA). pltR encodes an LysR-type transcriptional activator required for expression of divergently transcribed Plt biosynthetic genes. Here we provide evidence that Plt biosynthesis is negatively regulated by the quorum-sensing (QS) signal molecule (N-acyl homoserine lactone, AHL) synthase gene lasI and positively regulated by the orphan LuxR-type regulatory gene vqsR. pltR expression is modulated by four important global regulators including the two-component response regulatory gene gacA, the RNA-binding repressor RsmA, and the QS signal molecule synthase genes lasI and rhlI. pltR translation was almost completely inhibited in the gacA mutant M18G when compared with that in the wild-type strain of M18. We also observed significant enhancement of pltR translation in the rsmA mutant compared with wild-type strain M18. Moreover, mutation in lasI or rhlI gave rise to a significantly elevated level of pltR transcription in strain M18. However, no obvious difference was observed in pltR expression between the vqsR mutant and the wild-type of strain M18. These results highlight the fact that PltR likely at least partly plays an important mediator role in Gac/Rsm and the Las/Rhl regulatory pathways involved in Plt biosynthesis. [Copyright &y& Elsevier]

A Bacillus strain, denoted as PY-1, was isolated from the vascular bundle of cotton. Biochemical, physiological and 16S rDNA sequence analysis proved that it should belong to Bacillus subtilis. The PY-1 strain showed strong ability against many common plant fungal pathogens in vitro. The antibiotics produced by this strain were stable in neutral and basic conditions, and not sensitive to high temperature. From the culture broth of PY-1 strain, five antifungal compounds were isolated by acidic precipitation, methanol extraction, gel filtration and reverse-phase HPLC. Advanced identification was performed by mass spectrometry and nuclear magnetic resonance spectroscopy. These five antifungal compounds were proved to be the isomers of iturin A: A2, A3, A4, A6 and A7. In fast atom bombardment mass spectrometry/mass spectrometry collision-induced dissociation spectra, fragmentation ions from two prior linear acylium ions were observed, and the prior ion, Tyr-Asn-Gln-Pro-Asn-Ser-βAA-Asn-CO+, was first reported. Edited by Ming-Hua XU [ABSTRACT FROM AUTHOR]

Abstract: A novel sordarin derivative, moriniafungin (1), containing a 2-hydroxysebacic acid residue linked to C-3′ of the sordarose residue of sordarin through a 1,3-dioxolan-4-one ring was isolated from the fungus Morinia pestalozzioides. Isolation of moriniafungin employed a highly specific bioassay consisting of a panel of Saccharomyces cerevisiae strains containing chimeric eEF2 for Candida glabrata, Candida krusei, Candida lusitaniae, Crytpococcus neoformans, and Aspergillus fumigatus as well as wild type and human eEF2. Moriniafungin exhibited an MIC of 6μg/mL versus Candida albicans and IC50’s ranging from 0.9 to 70μg/mL against a panel of clinically relevant Candida strains. Moriniafungin was shown to inhibit in vitro translation in the chimeric S. cerevisae strains at levels consistent with the observed IC50. Moriniafungin has the broadest antifungal spectrum and most potent activity of any natural sordarin analog identified to date. [Copyright &y& Elsevier]

A trisaccharide, phenyl β-D-glucopyranosyl-(1→2)-[α-L-rhamnopyranosyl-(1→6)]-1-thio-β-D-glucopyranoside, of glycosylkaemferide, a resistance factor in carnations, was synthesized in a practical way. [ABSTRACT FROM AUTHOR]

Ipomoea muricata (L.) Jacq, locally known as ‘Tonkin’, has been used for generations by the Dominicans in the Philippines for medicinal purposes. The seeds, stems and leaves are said to be effective in treating several types of skin ailments such as chronic and gangrenous wounds, cuts and blisters due to burns. Scientific investigations to rationalize the reported medicinal uses of the plant were carried out at University of Santo Tomas. Botanists at the University did the identification and studied the cultivation and propagation of the plant. Pharmacists and chemists worked closely together on the ‘Tonkin’ seeds. The seeds were found to have both analgesic and antiseptic properties. Chemists identified indolizidine alkaloids in the seeds, to which the analgesic properties have been attributed. Antimicrobial and antifungal compounds were also identified. Different formulations of the crude drug have been made, namely, an ointment for the treatment of skin ailments, glycerol preparation for the treatment of pharyngitis and an otic preparation for the treatment of otitis externa. Limited clinical trials of these formulations were carried out in collaboration with the medical doctors. The clinical trial studies were supported by in vitro studies carried out by microbiologists. Basic research on this plant material is still continuing. Efforts are now underway for the commercial production of the Tonkin ointment. [ABSTRACT FROM AUTHOR]

Few antifungal agents are currently available for the treatment of fungal infections. Antimicrobial peptides (AMPs), which are natural molecules involved in the innate immune response of many organisms, represent a promising research method because of their broad killing activity. The aim of this study was to assess the activity of a frog AMP, [K 3 ]temporin-SHa, against some species of yeasts and moulds, and to further explore its activity against Candida albicans . MIC determinations were performed according to EUCAST guidelines. Next, the activity of [K 3 ]temporin-SHa against C. albicans was explored using time-killing curve experiments, membrane permeabilization assays, and electron microscopy. Finally, chequerboard assays were performed to evaluate the synergy between [K 3 ]temporin-SHa and amphotericin B or fluconazole. [K 3 ]temporin-SHa was found to be active in vitro against several yeasts with MIC between 5.5 and 45 µM. [K 3 ]temporin-SHa displayed rapid fungicidal activity against C. albicans (inoculum was divided into two in less than an hour and no viable colonies were recovered after 5 h) with a mechanism that could be due to membrane permeabilization. [K 3 ]temporin-SHa was synergistic with amphotericin B against C. albicans (FICI = 0.303). [K 3 ]temporin-SHa could represent an additional tool to treat several Candida species and C. neoformans .

• T. rugulosus O1 can increase the activities of resistant enzymes in grapes. • Functional annotation of all DEGs were done by GO and KEGG enrichment. • Grapes can produce a complex defense reactions after T. rugulosus O1 infection. Grapes are high nutritional and economic fruit but extremely vulnerable to fungus infections during postharvest storage. Our previous study found that the fungi, Talaromyces rugulosus O1 secretes ochratoxin A (OTA), which inflicts consumer health and economic value. This study found that T. rugulosus O1 has strong pathogenicity and spore germination to produce germ tubes to help it infect grapes. To better understand the molecular interaction between T. rugulosus O1 and grape, RNA sequencing (RNA-seq) was performed, and 5037 genes were identified as differentially expressed genes (DEGs) in grapes after T. rugulosus O1 infection. RNA-seq analysis revealed that T. rugulosus O1 infection, induced complex defense reactions in grapes, including an influx of Ca2+, oxidative burst, changes in GSH, plant hormone signal transduction, transcription factor regulation, overexpression of protein kinases, and biosynthesis of plant secondary metabolites. Our study found that the activity of the resistance enzymes in grapes was increased after T. rugulosus O1 infection, which is consistent with the RNA-seq results. Moreover, the accumulation of some antifungal compounds, including flavonoids, phenols, and lignin in grapes, increased grapes' antifungal ability. [ABSTRACT FROM AUTHOR]

Preformed inhibitory substances present in plants and/or antimicrobial compounds, phytoalexins, accumulating after exposure to microorganisms may play an important role in host-parasite relations. Ludwig et al. (1960) demonstrated that resistance of young barley coleoptiles to infection by Helminthosponum sativum may be related to the activity of antifungal compounds in acqueous extracts of these coleoptiles. The later identified hordatines, had a very marked effect on spore germination of several fungi (Stoessl 1967, Stoessl and Unwin 1970). The production of phytoalexins in diffusates of barley leaves has also been reported in response to Erysiphe graminis f. sp. hordei (Oku et al. 1975) and Selenophoma donacis (Evans and Pluck 1978). The drop-diffusate technique used in these studies, however, has serious limitations for assessing the contribution of a phytoalexin to resistance, because the outcome of interactions with powdery mildew is determined in epidermal tissue rather than in the infection droplet on the plant's surface. Only recently the formation of water-soluble phytoalexins and their apparent role in resistance of oat against Puccinia coronata has been demonstrated by Mayama et al. (1981). The objective of our work was to determine if inhibitory substances are present or formed in leaf tissue of spring barley and to note possible correlations between antifungal effects of such substances and the expression of adult plant resistance to powdery mildew during development. [ABSTRACT FROM AUTHOR]

A new antifungai compound was isolated from peel and flesh of unripe avocado fruits and identified as l-acetoxy-2,4-dihydroxy-n-heptadeca-16-ene. The maximal concentration of the anti- fungal monoene in unripe fruits was about 800 jzg ¦ g"1 fr.wt. During ripening the monoene decreased to 40 jug — g"1 fr.wt., concomitantly with the appearance of disease symptoms. The concentration of the previously described antifungai diene, l-acetoxy-2-hydroxy-4-oxo-heneicosa-12,15-diene (PRUSKY et al. 1982), in avocado peel was 1,600 jig — g"1 fr.wt. in unripe fruits, decreasing during ripening to 120 jug — g"1 fr.wt. At 750 fig — ml"1 the inhibition of germ tube elongation of germinated conidia by the antifungai monoene and the antifungai diene was 15 % and 44 %, respectively. A 1 : 1 mixture of both antifungai compounds in concentrations ranging from 50 to 750 fig — ml"1, showed synergistic activity and increased the percent of inhibited germ tubes of germinated conidia up to 15 % over the sum of activities of the separate compounds. The results are discussed in relation to the hypothesis that the antifungai diene and the antifungai monoene are involved in the quiescence of the germinated appressoria of CoUetotrkhum gloeosporioides in unripe avocado fruits. [ABSTRACT FROM AUTHOR]

Some substituted trans-hydroxystilbenes derived from pterostilbene and resveratrol were tested on germination, lethal effect and respiration of the conidia of Botrytis cinerea. These biological effects were related to the electronic character, to the lipophility of the substances and to their molecular volume. The products destroy the cellular membranes and could interfere with proteins of the electron transport systems. [ABSTRACT FROM AUTHOR]

Colletotrichum gloeosporioides produced exo-pectin lyase and protease in a) liquid cultures with incorporated washed cell wall material from unripe or ripe avocado and b) autoclaved immature fruit. The activity of exo-pectin lyase and protease produced in liquid cultures incorporating washed cell walls from immature fruits was almost the same as when washed cell walls from ripe fruits were incorporated. Ripe fruit tissue rotted by the fungus contained exo-pectin lyase, endo-polygalaeturonase (endo-PG) and protease. The endo-PG was found to be endogenous to avocado fruit, and had a pH optimum of 5.5. The pH optima of exo-pectin lyase and protease were 8.5 and 7.5 respectively in all three enzyme preparations. All these enzyme preparations completely macerated avocado fruit tissue discs in vitro in less than 3 h of incubation but not potato tuber discs. Neither immature nor ripe fruit contained substances, proteinaceous or otherwise, which could inhibit the exo-pectin lyase or protease activity of these preparations. The results indicated that C. gloeosporioides possesses sufficient enzyme potential to invade cell walls of unripe fruit and that the fruit tissue does not have a mechanism to inactivate such enzymes. [ABSTRACT FROM AUTHOR]

Information on microbial genome sequences is a powerful resource for accessing natural products with significant activities. We herein report the unveiling of lucensomycin production by Streptomyces achromogenes subsp. streptozoticus NBRC14001 based on the genome sequence of the strain. The genome sequence of strain NBRC14001 revealed the presence of a type I polyketide synthase gene cluster with similarities to a biosynthetic gene cluster for natamycin, which is a polyene macrolide antibiotic that exhibits antifungal activity. Therefore, we investigated whether strain NBRC14001 produces antifungal compound(s) and revealed that an extract from the strain inhibited the growth of Candida albicans . A HPLC analysis of a purified compound exhibiting antifungal activity against C. albicans showed that the compound differed from natamycin. Based on HR-ESI-MS spectrometry and a PubChem database search, the compound was predicted to be lucensomycin, which is a tetraene macrolide antibiotic, and this prediction was supported by the results of a MS/MS analysis. Furthermore, the type I polyketide synthase gene cluster in strain NBRC14001 corresponded well to lucesomycin biosynthetic gene cluster ( lcm ) in S. cyanogenus , which was very recently reported. Therefore, we concluded that the antifungal compound produced by strain NBRC14001 is lucensomycin.

Pyridine nucleotides such as a nicotinamide adenine dinucleotide (NAD) are known as plant defense activators. We previously reported that nicotinamide mononucleotide (NMN) enhanced disease resistance against fungal pathogen Fusarium graminearum in barley and Arabidopsis. In this study, we reveal that the pretreatment of nicotinamide (NIM), which does not contain nucleotides, effectively suppresses disease development of Fusarium Head Blight (FHB) in wheat plants. Correspondingly, deoxynivalenol (DON) mycotoxin accumulation was also significantly decreased by NIM pretreatment. A metabolome analysis showed that several antioxidant and antifungal compounds such as trigonelline were significantly accumulated in the NIM-pretreated spikes after inoculation of F. graminearum. In addition, some metabolites involved in the DNA hypomethylation were accumulated in the NIM-pretreated spikes. On the other hand, fungal metabolites DON and ergosterol peroxide were significantly reduced by the NIM pretreatment. Since NIM is relative stable and inexpensive compared with NMN and NAD, it may be more useful for the control of symptoms of FHB and DON accumulation in wheat and other crops. [ABSTRACT FROM AUTHOR]

The production of 4-hydroxyphenyllactic acid (4-HO-PLA), a novel antifungal compound, was studied in Lactobacillus sp. SK007 growth. When grown in MRS broth, the strain could produce 75 μg/ml HO-4-PLA, which was the highest reported so far. Tyrosine and 4-hydroxyphenylpyruvic acid (HO-4-PPA) supplements during fermentation could both increase the HO-4-PLA production yield, and the effect of HO-4-PPA on HO-4-PLA production was remarkably better than that of tyrosine. Using HO-4-PPA as substrate could effectively produce HO-4-PLA, which reached 1.26 mg/ml. [Copyright &y& Elsevier]

Abstract: A practical stereoselective synthesis of (6S)-5,6,dihydro-6-[(2R)-2-hydroxy-6-phenyl hexyl]-2H-pyran-2-one (1), a potent natural antifungal compound, is described. The sequence involves diastereoselective iodine-induced electrophilic cyclization, epoxide ring opening with a vinyl Grignard reagent and ring closing metathesis (RCM) as the key steps. [Copyright &y& Elsevier]