Evaluation of fungal contamination and mycotoxin production in maize silage

Agricultural activities involve daily use of maize silage as feed for livestock, which can be contaminated by mycotoxigenic molds. To evaluate fungal contamination, and the production of mycotoxins in maize silage we propose a multi-disciplinary approach utilizing PCR methods with genes of the aflatoxin (ver-1, omt-1 and apa-2), fumonisin (FUM1) and trichothecene (TRI6) biosynthesis pathways. To detect Aspergillus fumigatus, a 26S/intergenic spacer region of the rDNA complex was amplified. These specific PCR assays allowed three major groups of toxigenic fungi-like aflatoxin-producing Aspergilli, fumonisin and trichothecene-producing Fusaria, and the ubiquitous mold A. fumigatus, to be targeted. A multimycotoxin method is also proposed to simultaneously quantify seven mycotoxins (i.e., aflatoxin B₁, citrinin, deoxynivalenol, fumonisin B₁, gliotoxin, ochratoxin A, zearalenone) in maize silage by high-performance liquid chromatography coupled to mass spectrometry (HPLC–MS). These microbiological and analytical tools revealed three potentially toxigenic groups of fungi and A. fumigatus grown from mature maize silage (11 month old) that was collected in Normandy (France) and the mycotoxins aflatoxin B₁ (7.0–51.3 μg/kg), citrinin (10.1–14.2 μg/kg), deoxynivalenol (128.0–181.0 μg/kg) and gliotoxin (6.6–11.9 μg/kg). Results indicate that the combination of PCR and HPLC–MS can be used to assess fungal quality of maize silages.