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

NOTA 520 8 La contaminación de alimentos con hongos filamentosos productores de toxinas tiene efectos negativos sobre la salud animal y humana, además de causar pérdidas millonarias en la industria agroalimentaria. Entre los mohos toxigénicos más frecuentemente encontrados en los alimentos predominan las especies pertenecientes a los géneros Fusarium, Penicillium, Aspergillus y Alternaria. En el género Alternaria se incluyen numerosas especies patógenas y saprofitas ampliamente distribuidas en el suelo y la materia orgánica en descomposición. Como saprofito, Alternaria spp. persiste en forma de micelio durante los inviernos y, cuando las condiciones de humedad y temperatura son adecuadas, produce conidios que se diseminan con la ayuda del viento, agua, insectos, etc. Los conidios de Alternaria spp. que colonizan las plantas, germinan e infectan las hojas, tallos o frutos, donde provocan lesiones de diversa consideración según la intensidad de la infección, además de ocasionar alteraciones postcosecha en diversos cultivos vegetales. La alteración de frutas, hortalizas y otros cultivos por especies de Alternaria constituye un problema para el sector, porque el deterioro organoléptico ocasiona importantes pérdidas económicas. Pero además, implica una amenaza para la salud de los consumidores, debido a que diversas especies de este género producen micotoxinas, que permanecen activas en los alimentos procesados. Para evitar la presencia de micotoxinas de Alternaria spp. en los alimentos deben utilizarse medidas preventivas que minimicen la contaminación por especies toxigénicas o eviten su desarrollo...
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)...