Serge Krivobok

Fungal flora and ochratoxin A production in various food and feed in France

Summary To investigate the occurrence of potential ochratoxin A (OTA) producing moulds in foodstuffs, 11 food samples from the south-west part of France have been studied: 8 were contaminated with OTA (0.6 to 12.8 μg/kg). 120 filamentous fungi and 10 yeasts were isolated from these foodstuffs. Among the 30 genera isolated, the Mucedinacex (44%) were the most frequent, followed by Dematiaceae (26%) and Ascomycetes (10%). 20 strains were potential producers of OTA: Penicillium aurantiogriseum (10 strains), P. chrysogenum (1 strain), P. variabile (6 strains) and Aspergillus ochraceus (3 strains). Only 8 of these strains produced OTA in vitro when cultured in liquid complex medium, indicating that they are rather adapted to solid phase. These findings are to be related to the OTA contamination of human blood in these areas and in other parts of France.

Biotransformation of 2-acetylthiophene by micromycetes

SummaryThe biotransformation of 2-acetylthiophene by 800 strains of micromycetes has been investigated. Among them, 460 strains have been selected on solid media and cultivated in a liquid synthetic medium. Of these, 106 strains were able to completely deplete 2-acetylthiophene with or without production of intermediary metabolites. 2-Thienylglyoxylic acid was not detected but 72 strains produced 2-thiophenecarboxylic acid. Among them, eight strains have been selected for further optimization of this bioconversion.

Toxicity of walnut husk washing waters

Abstract Following a dispute between walnut producers and an anglers association, the toxicity of walnut washings has been determined and followed in a sewer and in a stream in a walnut production area near Grenoble (France) and compared with juglone toxicity. Toxicity of the washings has also been determined after storage at two different temperatures, with and without light. Juglone was found only to be responsible for a small part of this toxicity.