Mycoflora and Biodiversity of Black Aspergilli in Vineyard Eco-Systems

Abstract

Environmental conditions in vineyard eco-systems are of particular interest because they can influence the fungal populations associated with grapes, fungal–plant interactions, and production of secondary metabolites, including mycotoxins. Some fungal species are pathogenic to grapevines, infecting the roots, canes, leaves and fruit (Hewitt, 1988; Tournas & Katsoudas, 2005). Grape contamination by different moulds occurs during vineyard preharvesting, harvesting and grape processing (Magnoli et al., 2003). Moulds commonly isolated from grapes are Alternaria, Cladosporium and B. cinerea, the latter causing bunch rot. Pathogenic and opportunistic species of Fusarium, Penicillium and Aspergillus can also colonize inducing grape disease. In heavily infected fruit, moulds alter chemical composition and mould enzymes adversely affect wine flavor and colour as well as yeast growth during alcoholic fermentation (Fleet, 1999; Fleet, 2001). Some vineyard fungal species are capable of producing toxic secondary metabolites (mycotoxins) in infected tissue, which may contaminate grapes and grape products such as wine, grape juice and dried vine fruit (reviewed in Nielsen et al., 2009). The mycotoxins of greatest significance include aflatoxins, citrinin, patulin and ochratoxin A (OTA) and recently fumonisin B2 (FB2) (Frisvad et al., 2007; Logrieco et al., 2010; Morgensen et al., 2010a, 2010b; Susca et al., 2010). The most important mycotoxin in grapes and the grape-wine chain is OTA first reported by Zimmerli and Dick (1996). It has nephrotoxic, carcinogenic (2B group) (IARC, 1993), teratogenic and immunotoxic effects (Abarca et al., 2001; Castegnaro & Pfohl-Leszkowicz, 2002, Da Rocha et al., 2002; Pfohl-Leszkowicz et al., 2002; Petzinger & Weidenbach, 2002; Vrabcheva et al., 2000). Thereafter, several authors reported OTA contamination in wine and the presence of OTA-producing fungi in grapes in different winegrowing areas around the world (Battilani et al., 2006; Leong et al., 2007; Medina et al., 2005; Sage et al., 2004; Tjamos et al., 2004). The contamination of grapes with OTA can occur in the field, even without visible symptoms, while the grapes are still on the vine (Serra et al. 2006).