Detección de Alternaria spp mediante técnicas genéticas como índice de calidad de materias primas y marcador de bioseguridad en productos hortofrutícolas frescos y procesados

Abstract

Food contamination with toxigenic filamentous fungi represents an important hazard for animal and human health, and it has also a considerable economic impact in the food industry. The toxigenic moulds most commonly found in foods belong to the genera Fusarium, Penicillium, Aspergillus and Alternaria. The genus Alternaria includes saprophytic and pathogenic species that are widely distributed in soil and organic matter in decomposition. Alternaria spp. persists as saprophytic mycelium in plant debris during winter. Under favourable conditions in the spring, the fungi produce spores that are carried by wind and splashing rain. The conidia infect the plant by entering through small wounds, stomata, or direct penetration. Diseases caused by Alternaria species are very common and have a worldwide distribution. Disease symptoms affect the stems, leaves and fruits, depending on the Alternaria species involved, and the intensity of infection. As plant pathogens, they can seriously affect agriculture by reducing crop yield in the field and causing considerable economic losses to farmers and food processing industry. Moreover, certain species are also capable of producing mycotoxins and pose a health hazard as they can contaminate raw or manufactured plant products like juices, sauces and preserves, thereby entering the human food chain. To avoid the presence of Alternaria spp. mycotoxins in foodstuffs, preventive measures should be applied to minimize contamination by toxigenic species or prevent their development. Furthermore, availability of rapid methods for the early detection of Alternaria spp. is necessary in order to assess quality and safety control of raw materials and processed products in the food industry. The current routine technique for detection and identification of Alternaria spp. often requires culture isolation and further morphological and physiological characterization (Ellis and Ellis, 1997; Samson et al., 2004). However, this process is tedious and time-consuming, which hampers its use for routine analysis. Advances in molecular biology have allowed the development of new fungal identification and detection techniques based on DNA analysis. Among genetic techniques currently applied to detection and identification of toxigenic moulds in foodstuffs, polymerase chain reaction (PCR) is the most common approach due to its high sensitivity, specificity, and speed (Niessen, 2007)...