Antifungal mechanism of Bacillus marinus B-9987

Abstract:

Abstract: [Objective] We had a study on the antifungal effect of the metabolite BMME-1 from Bacillus marinus B-9987, in order to reveal the antifungal mechanism of it. [Methods] The permeability of the Alternaria solani was test by spectrophotometer after the treatment with crude extracts of B-9987. The composition of cell wall and the sterol components of the fungal plasmalemma of Alternaria solani was analyzed with Infrared Spectrum and GC-MS, respectively. [Results] We found that the metabolites of B-9987 had strong antifungal activity with MIC50 and MFC value being 6.2mg/L and 50mg/L. The absorbance in extracellular fluid detection showed that the tegument of the fungi was impaired. The detection of glucan and chitin indicated the change in the structure of the cell wall. The absorption peak of the carbon-hydrogen bond, β-glucosidic bond, carbon-oxygen bond was attenuated but the hydroxyl, carbonyl absorption was enhanced on the contrary. There were only one peak change in chitin chromatogram on the absorption of amide linkage comparing to the control. These changes on the structure may affect the stability of the fungal cell wall. Ergosterol was the predominant component of sterol with the proportion of 62.52±3.31% in control cells, but showed a decline during treatment with BMME-1 at a concentration of 56.36±2.52%. Accumulation of coprostanol, the precursor of ergosterol ,was found in the test. [Conclusion] From the result we can conclude that the antifungal mechanism of the crude extracts was interfering of ergosterol synthesis resulting in the change on permeability, and also mainly changed the structure of the cell wall, mainly acting on the glucan synthesis.

Key words:Keywords: Bacillus marinus; antifungal mechanism; glucan; chitin; ergosterol