Water activity and temperature effects on growth and mycotoxin production byAlternaria alternatastrains isolated from Malbec wine grapes

Abstract

Temperature and a conditions that allows growth and mycotoxin production are those normally found during wine grape ripeness in the field. Therefore, efforts should be made to prevent Alternaria presence and mycotoxin production in wine grapes.

Natural occurrence and production of tenuazonic acid in wine grapes in Argentina

“…In a previous work, we have found that temperature, a W , incubation time and strain type, were influencing factors in TA production by three A . alternata strains isolated from wine grapes in a synthetic nutrient media similar to grape composition (SN media) (Prendes et al., ). However, several works have demonstrated that fungal strains, producers of toxins in synthetic media, were not producers in natural substrates (Betina, ; Viñas et al., ).…”

“…To investigate these possibilities, this work analyzed for the first time TA production in wine grapes and the effect of temperature (15°C, 25°C, and 35°C) and incubation time (10, 17, and 24 days) using the three A . alternata strains that previously showed toxin production in a medium similar to grape composition (SN media) (Prendes et al., ).…”

“…Alternaria is an opportunistic pathogen, whose predominance in DOC San Rafael and its ability to produce high TA levels have been demonstrated (Prendes et al, 2015(Prendes et al, , 2017). This study also shows that mycotoxins could be present even in healthy wine grapes, probably as a result of a previous infection in surrounding tissues or the capability of fungi to produce mycotoxins under unfavorable conditions for growth (Barkai-Golan & Paster, 2008).…”

“…Fungal growth and mycotoxin production are the result of complex interactions between diverse biotic and abiotic factors, and knowledge of the effect of each involved factor is crucial for prediction, understanding, and prevention of mycotoxins contamination in food and by-products (Sanchis & Magan, 2004). In a previous work, we have found that temperature, a W , incubation time and strain type, were influencing factors in TA production by three A. alternata strains isolated from wine grapes in a synthetic nutrient media similar to grape composition (SN media) (Prendes et al, 2017). However, several works have demonstrated that fungal strains, producers of toxins in synthetic media, were not producers in natural substrates (Betina, 1989;Viñas et al, 1992).…”

“…Moreover, we recently found high and sustained levels of TA production by three A . alternata strains previously isolated from Malbec in a synthetic nutrient media similar to grape composition under water activity ( a W ) and temperature conditions normally found during wine grape ripeness in the field (Prendes, Zachetti, Pereyra, Morata de Ambrosini, & Ramirez, ). However, since food components and nutrient availability may interfere in metabolite biosynthesis of contaminant fungi (Barkai‐Golan & Paster, ), elucidating TA production and its major influencing factors in wine grapes is necessary.…”