Studies on the dynamics of the production of destruxins by Metarhizium anisopliae - Direct high-performance liquid chromatographic and fast atom bombardment mass spectrometric analysis correlated with biological activity tests

In this work, the new strain Ma23 of the fungus Metarhizium anisopliae is demonstrated to be an effective source of destruxins, known insecticidal cyclodepsipeptides, under optimized culture conditions. The dynamics of the destruxin production is analysed by fast atom bombardment MS and HPLC, using wide-pore reversed-phase packings without any pretreatment of the culture media samples. By this approach, we show that twelve different destruxins are produced by M. anisopliae, The most abundant toxins have been unequivocally identified and HPLC quantitation shows that E destruxin, the most toxic compound of the series, accounts for similar to 35-40% of the whole toxin production from Ma23. A good correlation between the pathogenic effect of the fungal samples and amounts of destruxins produced is also demonstrated with an optimum of toxicity after four days.