New untargeted metabolic profiling combining mass spectrometry and isotopic labeling: application on Aspergillus fumigatus grown on wheat.

Characterization of fungal secondary metabolomes has become a challenge due to the industrial applications of many of these molecules, and also due to the emergence of fungal threats to public health and natural ecosystems. Given that, the aim of the present study was to develop an untargeted method to analyze fungal secondary metabolomes by combining high-accuracy mass spectrometry and double isotopic labeling of fungal metabolomes. The strain NRRL 35693 of Aspergillus fumigatus, an important fungal pathogen, was grown on three wheat grain substrates: (1) naturally enriched grains (99% 12C), (2) grains enriched 96.8% with 13C, (3) grains enriched with 53.4% with 13C and 96.8% with 15N. Twenty-one secondary metabolites were unambiguously identified by high-performance liquid chromatography–high-resolution mass spectrometry (HPLC–HRMS) analysis. AntiBase 2012 was used to confirm the identity of these metabolites. Additionally, on the basis of tandem mass spectrometry (MSn) experiments, it was possible to i...