PCR Detection of Alternaria spp. in Processed Foods, Based on the Internal Transcribed Spacer Genetic Marker

The genus Alternaria is considered one of the most important fungal contaminants of vegetables, fruits, and cereals, producing several mycotoxins that can withstand food processing methods. Conventional methods for Alternaria identification and enumeration are laborious and time-consuming, and they might not detect toxigenic molds inactivated by food processing. In this study, a PCR method has been developed for the rapid identification of Alternaria spp. DNA in foodstuffs, based on oligonucleotide primers targeting the internal transcribed spacer (ITS) 1 and ITS2 regions of the rRNA gene. The specificity of the Alternaria-specific primer pair designed (Dir1ITSAlt-Inv1ITSAlt) was verified by PCR analysis of DNA from various Alternaria spp., and also from several fungal, bacterial, yeast, animal, and plant species. The detection limit of the method was 10(2) CFU/ml in viable culture, heated culture, or experimentally inoculated tomato pulp. The applicability of the method for detection of Alternaria spp. DNA in foodstuffs was assessed by testing several commercial samples. Alternaria DNA was detected in 100% of spoiled tomato samples, 8% of tomato products, and 36.4% of cereal-based infant food samples analyzed.