title: Induction of chlamydospore formation in fusarium by cyclic lipopeptide antibiotics from Bacillus subtilis C2.
abstract: The culture filtrate of Bacillus subtilis strain C2 showed strong activity against the pathogenic fungus Fusarium solani f. sp. radicicola. A partially purified fraction (PPF) from the extract induced chlamydospore formation in Fusarium. Reverse-phase high performance liquid chromatography yielded 8 different fractions, six of which had chlamydospore-inducing activity. Mass spectrometry and nuclear magnetic resonance analyses identified the main active constituent as C(17) fengycin A (FA17), a cyclic lipopeptide. The effect of FA17 on morphology and physiology of two Fusarium species was dependent on the lipopeptide concentration. When challenged with FA17 at concentrations (0.5, 8, 64 μg ml(-1)) below the minimum inhibitory concentration (MIC) (128 μg ml(-1)), two species of Fusarium formed chlamydospores from hyphae, germ tubes, or inside the conidia within 2 days. At concentrations close to the MIC, FA17 caused Fusarium to form sparse and swollen hyphae or lysed conidia. The other five fractions were identified as fengycin A homologues. The homologues could also induce chlamydospore-like structures in 17 species of filamentous fungi including some specimens that do not normally produce chlamydospores, according to their taxonomic descriptions. Like other chlamydospores, these structures contained nuclei and lipid bodies as revealed by DAPI and Nile Red staining, and could germinate. This is the first study to demonstrate that under laboratory conditions fengycin, an antifungal lipopeptide produced by B. subtilis, can induce chlamydospore formation in Fusarium and chlamydospore-like structures in many filamentous fungi.
authors.affiliation: Laboratory for Conservation and Utilization of Bio-Resources and Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, Kunming 650091, People's Republic of China. leelei58@yahoo.cn
authors.forename: Lei
authors.initials: L
authors.lastname: Li
authors.forename: Mingchuan
authors.initials: M
authors.lastname: Ma
authors.forename: Rong
authors.initials: R
authors.lastname: Huang
authors.forename: Qing
authors.initials: Q
authors.lastname: Qu
authors.forename: Guohong
authors.initials: G
authors.lastname: Li
authors.forename: Jinwei
authors.initials: J
authors.lastname: Zhou
authors.forename: Keqin
authors.initials: K
authors.lastname: Zhang
authors.forename: Kaiping
authors.initials: K
authors.lastname: Lu
authors.forename: Xuemei
authors.initials: X
authors.lastname: Niu
authors.forename: Jun
authors.initials: J
authors.lastname: Luo
mesh_terms: D000900:Anti-Bacterial Agents / Q000302:isolation & purification / Q000494:pharmacology*; D001412:Bacillus subtilis / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D056148:Chromatography, Reverse-Phase; D005670:Fusarium / Q000187:drug effects* / Q000502:physiology; D055666:Lipopeptides / Q000302:isolation & purification / Q000494:pharmacology*; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008826:Microbial Sensitivity Tests; D010456:Peptides, Cyclic / Q000302:isolation & purification / Q000494:pharmacology*; D013172:Spores, Fungal / Q000502:physiology
chemical_list: D000900:Anti-Bacterial Agents; C577303:C17 fengycin A; D055666:Lipopeptides; D010456:Peptides, Cyclic