Cross-domain binding of anti-fibrillation peptide TNGQ to islet amyloid polypeptide provides cytoprotective effects in giant unilamellar vesicles and pancreatic β-cells.

Islet amyloid polypeptide (IAPP) fibrillation induces β-cell dysfunction and toxicity in patients with type 2 diabetes. Cytotoxicity is caused by the ability of IAPP fibrils and fibrillar intermediates to permeate the cellular membrane of pancreatic β-cells, trigger endoplasmic reticular stress, induce reactive oxygen species production, and upregulate apoptosis-related genes. Thus, inhibition of IAPP fibrillation is of great interest for preventing associated cytotoxicity.

Fungal membrane determinants affecting sensitivity to antifungal cyclic lipopeptides from Bacillus spp.

Bacillus spp. produce numerous antimicrobial metabolites. Among these metabolites, cyclic lipopeptides (CLP) including fengycins, iturins, and surfactins are known to have varying antifungal activity against phytopathogenic fungi.

Characterization of Arthropeptide B, an Antifungal Cyclic Tetrapeptide from Arthrobacter humicola.

Disease suppressive composts are known, yet little information on the potential role of specific microbial antagonist within are available. Arthrobacter humicola isolate M9-1A has been obtained from a compost prepared from marine residues and peat moss. The bacterium is a non-filamentous actinomycete with antagonistic activity against plant pathogenic fungi and oomycetes sharing its ecological niche in agri-food microecosystems.

Arthropeptide A, an antifungal cyclic tetrapeptide from isolated from disease suppressive compost.

In an effort to describe bioactive antifungal compounds from antagonistic bacteria with potential for biocontrol of plant pathogens, a strain of was collected from plant disease suppressive compost prepared from composted material of marine origin. Few natural products have been characterized from the non-filamentous Actinobacteria genus . A new cyclic tetrapeptide, cyclo-(L-Pro-L-Leu-L-γHyp-L-Tyr); arthropeptide A (), was isolated from the EtOAc soluble culture filtrate extract of M9-17 grown in MOLP broth.

Biological and chemical characterization of antimicrobial activity in Arthrobacter spp. isolated from disease-suppressive compost.

Antagonistic bacteria can act as biocontrol agents against various phytopathogens. Recently, Arthrobacter spp. demonstrated antifungal activity, but were not further characterized.

Pathogenicity and a TaqMan Real-Time PCR for Specific Detection of , a Bacterial Pathogen of Onions.

Bacterial diseases of onion are reported to cause significant economic losses. Brady, one of the pathogens causing the center rot on onions, has not yet been reported in Canada. We report the pathogenicity of on commercially available Canadian green onions (scallions).

Role of Lipid Composition in the Interaction and Activity of the Antimicrobial Compound Fengycin with Complex Membrane Models.

Fengycins are compounds produced by bacteria of the Bacillus genus with strong antifungal activity. In this work, lipids extracted from fungal and oomycetal molds were used to assess the ability of fengycin to bind and insert into complex membrane models prepared as Langmuir lipid monolayers. In addition, fengycin-induced leakage in liposomes prepared from these complex lipid extracts was also evaluated.

Supported lipid bilayers using extracted microbial lipids: domain redistribution in the presence of fengycin.

Fengycin is an antimicrobial cyclic lipopeptide known to interact with microbial cell membranes. To gain insight into the role of lipids in fengycin sensitivity, lipids extracted from Alternaria solani, Fusarium sambucinum, and Pythium sulcatum were analyzed and used in the preparation of supported lipid bilayers (SLBs). Total Internal Reflection Fluorescence Microscopy (TIRFM) was used to evaluate lipid phase separation within the SLBs and changes in domain distribution with the application of fengycin.

Domain redistribution within ergosterol-containing model membranes in the presence of the antimicrobial compound fengycin.

The cyclic lipopeptide fengycin, produced by Bacillus subtilis, exhibits its antimicrobial capabilities by altering the integrity of the cell membrane of plant pathogens. Previous work has correlated fengycin activity with membrane characteristics, such as sterol content. This work focused on the influence of fengycin on supported lipid bilayers containing varying levels of ergosterol.

Fungal Competitors Affect Production of Antimicrobial Lipopeptides in Bacillus subtilis Strain B9-5.

Bacillus subtilis has shown success in antagonizing plant pathogens where strains of the bacterium produce antimicrobial cyclic lipopeptides (CLPs) in response to microbial competitors in their ecological niche. To gain insight into the inhibitory role of these CLPs, B. subtilis strain B9-5 was co-cultured with three pathogenic fungi.

Microbial inhibitors of the fungus Pseudogymnoascus destructans, the causal agent of white-nose syndrome in bats.

Pseudogymnoascus destructans, the fungus that causes white-nose syndrome in hibernating bats, has spread across eastern North America over the past decade and decimated bat populations. The saprotrophic growth of P. destructans may help to perpetuate the white-nose syndrome epidemic, and recent model predictions suggest that sufficiently reducing the environmental growth of P.

Experimental Parameters Leading to Optimal Bilayers for Total Internal Reflection Fluorescence Microscopy Visualization.

Supported lipid bilayer systems were evaluated following various experimental procedures in an effort to determine their appropriateness for visualization using total internal reflection fluorescence (TIRF) microscopy. The incorporation and distribution of Texas Red® 1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine (TR-DHPE) was studied when incorporated into bilayers of variable lipid composition using different forms of mechanical shearing. Results showed that 0.

Physiological and molecular characterization of compost bacteria antagonistic to soil-borne plant pathogens.

Disease suppressive composts have the potential to mitigate the risks associated with chemical pesticides. One of the main characteristics responsible for the suppressive nature of composts is their microbiological populations. To gain insight into the determinants responsible for their suppressive effects, we assayed composts to (i) isolate and identify beneficial antagonistic bacteria, (ii) quantify their antifungal and anti-oomycetal activities, (iii) extract inhibitory compounds produced by the bacteria, and (iv) identify antimicrobial lipopeptides produced by these bacteria.

Combating Antimicrobial Resistance in Foodborne Microorganisms.

This review addresses an important public health hazard affecting food safety. Antimicrobial agents are used in foods to reduce or eliminate microorganisms that cause disease. Many traditional organic compounds, novel synthetic organic agents, natural products, peptides, and proteins have been extensively studied for their effectiveness as antimicrobial agents against foodborne Campylobacter spp.

Effect of tea tree (Melaleuca alternifolia) oil as a natural antimicrobial agent in lipophilic formulations.

There has been increased interest surrounding the use of tea tree oil (TTO) as a natural antimicrobial. In this study, the antimicrobial activity of TTO and its components were investigated in vitro and in a predominantly lipid-based personal care formulation. In vitro, TTO showed minimal inhibitory concentrations of 0.

Interaction of antimicrobial cyclic lipopeptides from Bacillus subtilis influences their effect on spore germination and membrane permeability in fungal plant pathogens.

Bacillus subtilis cyclic lipopeptides are known to have various antimicrobial effects including different types of interactions with the cell membranes of plant pathogenic fungi. The various spectra of activities of the three main lipopeptide families (fengycins, iturins, and surfactins) seem to be linked to their respective mechanisms of action on the fungal biomembrane. Few studies have shown the combined effect of more than one family of lipopeptides on fungal plant pathogens.

Cellular Lipid Composition Affects Sensitivity of Plant Pathogens to Fengycin, an Antifungal Compound Produced by Bacillus subtilis Strain CU12.

Fengycin is an antimicrobial cyclic lipopeptide produced by various Bacillus subtilis strains, including strain CU12. Direct effects of fengycin include membrane pore formation and efflux of cellular contents leading to cell death in sensitive microorganisms. In this study, four plant pathogens were studied in order to elucidate the role of membrane lipids in their relative sensitivity to fengycin.

Regulation of the Rana sylvatica brevinin-1SY antimicrobial peptide during development and in dorsal and ventral skin in response to freezing, anoxia and dehydration.

Brevinin-1SY is the only described antimicrobial peptide (AMP) of Rana sylvatica. As AMPs are important innate immune molecules that inhibit microbes, this study examined brevinin-1SY regulation during development and in adult frogs in response to environmental stress. The brevinin-1SY nucleotide sequence was identified and used for protein modeling.

Investigating the effects of L- to D-amino acid substitution and deamidation on the activity and membrane interactions of antimicrobial peptide anoplin.

Isolated from the venom sac of solitary spider wasp, Anoplius samariensis, anoplin is the smallest linear α-helical antimicrobial peptide found naturally with broad spectrum activity against both Gram-positive and Gram-negative bacteria, and little hemolytic activity toward human erythrocytes. Deamidation was found to decrease the peptide's antibacterial properties. In the present work, interactions of amidated (Ano-NH2) and deamidated (Ano-OH) forms of anoplin as well as Ano-NH2 composed of all D-amino acids (D-Ano-NH2) with model cell membranes were investigated by means of Langmuir Blodgett (LB) technique, atomic force microscopy (AFM), X-ray photoemission electron microscopy (X-PEEM) and carboxyfluorescein leakage assay in order to gain a better understanding of the effect of these peptide modifications on membrane binding and lytic properties.

Recombinant protein secretion in Pseudozyma flocculosa and Pseudozyma antarctica with a novel signal peptide.

Secretion of recombinant proteins aims to reproduce the correct posttranslational modifications of the expressed protein while simplifying its recovery. In this study, secretion signal sequences from an abundantly secreted 34-kDa protein (P34) from Pseudozyma flocculosa were cloned. The efficiency of these sequences in the secretion of recombinant green fluorescent protein (GFP) was investigated in two Pseudozyma species and compared with other secretion signal sequences, from S.

Usefulness of heterologous promoters in the Pseudozyma flocculosa gene expression system.

The basidiomycetous fungus Pseudozyma flocculosa represents a promising new host for the expression of complex recombinant proteins. Two novel heterologous promoter sequences, the Ustilago maydis glyceraldehyde-3-phosphate dehydrogenase (GPD) and Pseudozyma tsukubaensis alpha-glucosidase promoters, were tested for their ability to provide expression in P. flocculosa.

Fatty acid profiles of polar and non-polar lipids of Pleurotus ostreatus and P. cornucopiae var. 'citrino-pileatus' grown at different temperatures.

The application of fatty acid (FA) composition data has now extended to studies of physiology, chemotaxonomy, and intrageneric differentiation, as well as to studies of human nutrition. Environmental factors such as nutritional components, oxygen, and temperature are known to affect lipid content and composition in living organisms, including fungi. In the present study, the polar and non-polar lipid content of Pleurotus ostreatus and P.

Role of lipid composition and lipid peroxidation in the sensitivity of fungal plant pathogens to aluminum chloride and sodium metabisulfite.

Aluminum chloride and sodium metabisulfite have shown high efficacy at low doses in controlling postharvest pathogens on potato tubers. Direct effects of these two salts included the loss of cell membrane integrity in exposed pathogens. In this work, four fungal potato pathogens were studied in order to elucidate the role of membrane lipids and lipid peroxidation in the relative sensitivity of microorganisms exposed to these salts.

Dependence of arbuscular-mycorrhizal fungi on their plant host for palmitic acid synthesis.

Lipids are the major form of carbon storage in arbuscular-mycorrhizal fungi. We studied fatty acid synthesis by Glomus intraradices and Gigaspora rosea. [(14)C]Acetate and [(14)C]sucrose were incorporated into a synthetic culture medium to test fatty acid synthetic ability in germinating spores (G.