Water activity and temperature effects on growth and mycotoxin production by Alternaria alternata strains isolated from Malbec wine grapes

PRENDES, L. P.; ZACHETTI, V.G.L.; PEREYRA, A.; MORATA DE AMBROSINI V.I.; RAMIREZ, M.L.

JOURNAL OF APPLIED MICROBIOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2017 vol. 122 p. 481 - 492

1364-5072

Aims: To study the effects of water activity (aW; 099, 098, 097, 096 and095), temperature (15, 25 and 30°C), incubation time (7?28 days), and theirinteractions on mycelial growth and alternariol (AOH), alternariolmonomethyl ether (AME) and tenuazonic acid (TA) mycotoxin production ona synthetic nutrient (SN) media similar to grape composition by three strainsof Alternaria alternata isolated from wine grapes from Argentina.Methods and Results: Interacting conditions of aW, temperature and time ofincubation were used to examine growth and mycotoxin production. Allstrains were able to grow at 095 aW, but maximum growth rates wereobtained at 099 aW and 25°C. Maximum levels of AOH, AME and TA wereobtained at 099 aW and 25°C, but high amounts of TA were also obtained at096 aW and 15 or 30°C. Production of AOH and AME was favoured over TAat 25°C. TA levels were more sustained than AOH and AME.Conclusion: The optimum and marginal conditions for growth and mycotoxinproduction by A. alternata on a SN media similar to grape composition werein agreement, but certain stressful conditions for growth evaluated alsopromote mycotoxin production.Significance and Impact of the Study: Temperature and aW conditions thatallows growth and mycotoxin production are those normally found duringwine grape ripeness in the field. Therefore, efforts should be made to preventAlternaria presence and mycotoxin production in wine grapes.