Physiological behaviour of gliotoxigenic Aspergillus fumigatus sensu stricto isolated from maize silage under simulated environmental conditions.

ALONSO V, ; DÍAZ VERGARA L,; AMINAHUEL C,; PEREYRA C,; PENA G, ; TORRES A, ; DALCERO A,; RODRÍGUEZ C., C.M. PEREYRA, C. LEDESMA, M. MANCINI, M. BONANSEA, F. BONATTO, V. REYNOSO, C.A.R. ROSA, A. DALCERO, CAVAGLIERI L., C. PROSPERI

FOOD ADDITIVES AND CONTAMINANTS

TAYLOR & FRANCIS LTD

Año: 2015 vol. 32 p. 236 - 244

0265-203X

The environmental conditions play a key role in the fungal development. During the silage production process, humidity, oxygen availability and pH, are varying among lactic-fermentation phases and among different silage sections. The aim of this work was to study the physiological behavior of gliotoxicogenic Aspergillus fumigatus strains isolated from maize silage under simulated natural physicochemical conditions -different water activities (aW), temperatures (Tº), pH and oxygen pressure - onto the growth parameters (growth rate and lag phase) and gliotoxin production. The silage was made with the harvested whole maize plant that was chopped and used for trench type silos fabrication. Water activity and pH of the samples of silage were determined. Total fungal counts were performed onto Dichloran Rose Bengal Chloranphenicol agar and Dichloran 18% Glicerol agar. The morphological identification of A. fumigatus was performed with different culture media and growth temperature for the observation of microscopic and macroscopic characteristics. The gliotoxin production the A. fumigatus was determined for HPLC. All strains isolated were morphologically identified as A. fumigatus. Two A. fumigatus strains isolated from the silage samples were selected for the ecophysiological study (A. fumigatus sensu stricto RC031 and RC032). The results of this investigation showed that the fungus grows in the simulated natural physicochemical conditions of corn silage and produce gliotoxin. The study of the physiologycal behaviour of gliotoxigenic A. fumigatus under simulated environmental conditions allows us to predict its behavior in silage and this fact will enable in the future, seek appropriate control strategies to prevent the spread of this fungus and toxin production that lead to impairment and reduced quality of silage.