Novel use of the isoepoxydon dehydrogenase gene probe of the patulin metabolic pathway and chromatography to test penicillia isolated from apple production systems for the potential to contaminate apple juice with patulin

Penicillia isolated from apple production systems were analysed with a probe for the isoepoxydon dehydrogenase (IDH) gene of the patulin metabolic pathway. Patulin production was also determined. These were used to assess which fungi had the potential to contaminate apple juice with patulin. Penicillium expansum was the most frequently isolated species, and the isolates were consistent for patulin production and the IDH gene. P. roquefortii was also positive for the traits. The presence of the gene in some strains of P. brevicompactum was confirmed and evidence of patulin production is presented. Most other species were negative. Some isolates were positive for the IDH gene and negative for patulin production. All fungi with the potential to produce patulin should be considered for optimal control of apple product contamination.