Using direct electrospray mass spectrometry in taxonomy and secondary metabolite profiling of crude fungal extracts

Important information about sample composition can be obtained within a few minutes by injecting a complex mixture like a crude extract of a fungal culture prepared for standard HPLC analysis directly into an electrospray mass spectrometer using a FIA-ESMS type of setup. The limited fragmentation aud high sensitivity of ESMS where used in this study to provide 'mass profiles' from ethylacetate/methanol/chloroform extracts from cultures of 10 the most common Penicillium species associated with stored cereals. The analytical parameters were optimized to reduce fragmentations and reactions in ESMS hence only the protonated or sodiated ions were observed for most compounds. The analysis demonstrated that ions corresponding to the protonated molecular ions (M + H⁺) from most of the known secondary metabolites and mycotoxins produced these species by could observed in the ESMS spectra. A number of other distinct species specific ion were observed as well. The 10 different species could be discriminated either by ions corresponding to known or unknown metabolites. By creating a database of mass spectra obtained from analysis of different species using the facility included in standard MS software it was possible to use a simple library search to identify most of the species included in this study on the basis of their mass spectra.