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SESSION 2: SECONDARY METABOLITES – BIOCHEMISTRY,
BIOSYNTHESIS, FEED AND FOOD SAFETY
P15 - Effect of pH and temperature on Fusarium
langsethiae growth and on T2 and HT2 toxins
production in liquid medium
E. Rondags 1 R. Fournier 2 , P. Boivin 2 , X. Framboisier 1 , M. Fick 1
1 Laboratoire Réactions et Génie des procédés, CNRS (UMR 7274), Université de Lorraine, 2, avenue
de la Forêt de Haye, TSA 40602, 54518 Vandœuvre-lès-Nancy, France; 2Institut Français des
Boissons de la Brasserie-Malterie, 7, rue du Bois de la Champelle, 54500 Vandoeuvre-lès-Nancy,
France
E-mail: emmanuel.rondags@univ-lorraine.fr
Fusarium langsethiae is a pathogenic fungus affecting cereal cultures and the
downstream transformation chains. Contamination by this micro-organism is
generally associated with the production of the highly toxic T2 and HT2
mycotoxins. However, in the barley-malt-beer chain, the relationship between
Fusarium langsethiae contamination level, growth and toxins production is only
partially understood, mainly because contamination occurs on natural complex
substrates in polyphasic media. In order to assess this concern, growth and toxins
production were monitored in perfectly stirred liquid conditions, as a function of
the medium initial pH and cultivation temperature. This study shows that Fusarium
langsethiae is able to grow at pH’s ranging from 4.5 to 9 and at temperatures
between 10 and 30°C. Optimal growth conditions are close to pH neutrality and
25°C. T2 and HT2 production occurs from pH’s of 4.5 to 9, with an optimum
located between pH 6.5 and 7.5. As far as temperature is concerned, toxin
production takes place in the 15 to 30°C range, with a strong optimum at 25°C.
The effects of temperature and pH on Fusarium growth and toxinogenesis have
then been modelized with classical quadratic functions in order to dispose of a
prediction tool in liquid media. What is more, no relationship was established
between growth and T2 and HT2 production. At last, comparisons between
Erlenmeyer’s flasks cultures without immobilized biomass and bioreactor cultures
containing mainly adsorbed Fusarium langsethiae indicate that the toxinogenesis
is due to immobilized non growing cells. This finding could explain the lack of
relationship between Fusarium langsethiae and T2 and HT2 contamination levels
in the fields and on the cereal-derived products. This could have strong
consequences on the prevention strategies developed either in the field or in the
transformation processes.
Keywords: Fusarium langsethiae, T2, Barley-Malt-Beer, toxinogenesis
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