Effect of waqter activity and temperature on growth of Fsuarium meridionales and deoxynvialenol and nivalenol production

CHIOTTA M L; RYBECKY A; CHULZE , S.N

Ghent

Congreso; 1st MYCOKEY International Conference Global Mycotoxin Reduction in the Food and Feed Chain; 2017

Universidad de Ghent Mucokey Project

Abstract: Members of the Fusarium graminearum species complex (FGSC) can infect several crops causing diseases such as Fusarium head blight in wheat, Gibberella ear rot and stalk rot in maize and root rot in soybean. These species can infected the grains which are often contaminated with type B trichothecenes such as deoxinivalenol (DON), nivalenol (NIV) and its acetylated forms. In a previous study done in Argentina was showed that F. meridionale was the second species within FGSC more frequently isolated from soybean and showed similar pathogenicity as F. graminearum sensu stricto. The aim of this study was: to determine the effect water activity, temperature and strain on F. meridionalegrowth and DON and NIV production on 2% (w/v) soybean agar. The optimal growth conditions for F. meridionale were 0.98?0.995 aW and 25 C. All the strains reached a higher growth rate at 20 C in comparison with 30 C and growth rate increased with increasing aW. The analysis on the effect of each factor (temperature, aW and strain) and the combination of them showed that both temperature and aW were the most significant parameters affecting F. meridionale growth. Deoxynivalenol production by F. meridionale was favoured at 25 C and 0.96 aW with levels ranging from 0.9 to 46.6 g g􀀀1. None of the strains evaluated showed high production levels at either 20 C or 30 C, being higher theproduction at 30 C than at 20 C. At 0.98?0.995 aW and 30 C conditions DON production increased; while at 20 C different production patterns were observed depending on the strain and the aW evaluated. As regards NIV production, the toxigenic profile was different depending on the strain. Fusarium meridionale B2300 produced the highest levels at 30 C and 0.98 aW, while the optimal NIV production by F. meridionale F5043 and F5048 was observed at 20 C and 0.98 aW. These results could be explained based on isolation region of the strain, since F. meridionale F5043 and F5048 were isolated from the same geographic area in Argentina, while F. meridionale B2300 was isolated from Brazil.Temperature and water activity were the most important factors that affect DON and NIV production, Toxins 2017, 9, 276 65 of 117 respectively (p < 0.05). Both DON and NIV production could be a toxicological risk in soybean, since these toxins could be produced in this crop at pre-harvest stage