title: Inhibition of agronomically relevant fungal phytopathogens by tyrocidines, cyclic antimicrobial peptides isolated from Bacillus aneurinolyticus.
abstract: The tyrocidines, a complex of analogous cyclic decapeptides produced by Bacillus aneurinolyticus, exhibited noteworthy activity against a range of phytopathogenic fungi, including Fusarium verticillioides, Fusarium solani and Botrytis cinerea. The activity of the tyrocidine peptide complex (Trc mixture) and purified tyrocidines exhibited minimum inhibition concentrations below 13 µg ml(-1) (~10 µM) and was significantly more potent than that of the commercial imidazole fungicide, bifonazole. Although the tyrocidines' activity was negatively influenced by the presence of Ca(2+), it remained unaffected by the presence of Mg(2+), Na(+) and K(+). Microscopic analysis revealed significant impact on the morphology of F. solani and Bot. cinerea including retarded germination and hyperbranching of hyphae. Studies with membrane-impermeable dyes, SYTOX green and propidium iodide suggested that the main mode of action of tyrocidines involves the disruption of fungal membrane integrity. Because of the tyrocidines' broad spectrum and potent antifungal activity, possible multiple targets reducing the risk of overt resistance and general salt tolerance, they are promising candidates that warrant further investigation as bio-fungicides.
authors.affiliation: BIOPEP Peptide Group, Department of Biochemistry, University of Stellenbosch, Private Bag X1, Matieland 7600, South Africa.
authors.forename: Anscha M
authors.initials: AM
authors.lastname: Troskie
authors.affiliation: BIOPEP Peptide Group, Department of Biochemistry, University of Stellenbosch, Private Bag X1, Matieland 7600, South Africa.
authors.forename: Abré
authors.initials: A
authors.lastname: de Beer
authors.affiliation: BIOPEP Peptide Group, Department of Biochemistry, University of Stellenbosch, Private Bag X1, Matieland 7600, South Africa.
authors.forename: Johan A
authors.initials: JA
authors.lastname: Vosloo
authors.affiliation: Department of Microbiology, University of Stellenbosch, Private Bag X1, Matieland 7600, South Africa.
authors.forename: Karin
authors.initials: K
authors.lastname: Jacobs
authors.affiliation: BIOPEP Peptide Group, Department of Biochemistry, University of Stellenbosch, Private Bag X1, Matieland 7600, South Africa.
authors.forename: Marina
authors.initials: M
authors.lastname: Rautenbach
mesh_terms: D000935:Antifungal Agents / Q000494:pharmacology*; D056449:Bacillales / Q000378:metabolism*; D020171:Botrytis / Q000166:cytology / Q000187:drug effects*; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D005670:Fusarium / Q000166:cytology / Q000187:drug effects*; D008826:Microbial Sensitivity Tests; D008853:Microscopy; D010539:Permeability / Q000187:drug effects; D014440:Tyrocidine / Q000302:isolation & purification / Q000494:pharmacology*
chemical_list: D000935:Antifungal Agents; D014440:Tyrocidine