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DOI: 10.1055/s-0031-1282096
Fungal co-culture as a new source of antifungal metabolites
Microorganisms are a very rich source of secondary metabolites with antimicrobial potential [1]. In order to produce original metabolites from this source, strategies have to be developed to induce synthetic pathways triggered by genes that are often silent [2]. Nutritional or environmental stress can be used to activate these orphan pathways and lead to novel metabolites. Recently new approaches were developed using genomic approaches or interspecies crosstalk to induce the production of new compounds. In relation with this latter aspect our recent work on co-cultivation of microorganisms shows that new metabolites can be found with this approach [3]. In the course of a screen based on fungal confrontation, we identified intriguing morphological co-culture patterns such as a Trichophyton rubrum strain able to inhibit the growth of several other fungi at a distance on agar plates (Figure 1).
In order to identify fungal metabolites responsible for this long distance repulsion, confrontation zone and pure fungal strains were compared by UHPLC-TOF-MS fingerprinting using differential metabolomics. Data mining results in an efficient selection of stress induced molecules which were purified using preparative RP-HPLC-MS and subsequently identified by microflow NMR. The antifungal activity of biomarker was assessed in order to verify that the fungal long distance repulsion was related to these mycoalexins.
This innovative strategy can be used to search for original antifungal metabolites to eradicate resistant fungi such as Fusarium.
Keywords: fungal metabolites, co-culture, confrontation, anti-fungals
Acknowledgement: This work was supported by Swiss National Science Foundation Sinergia Grant CRSII3_127187 (to J.-L. W. and K. G.)
References: 1. Berdy J (2005)J Antibiot 58: 1–26
2. Scherlach K et al. (2009) Org Biomol Chem 7: 1753–1760
3. Glauser G et al. (2009)J Agric Food Chem 57: 1127–1134