In vitro transformation of ochratoxin A by animal microbioal floras.

Ochratoxin A is hydrolysed to ochratoxin alpha by the centrifugal pellet of rat caecal contents containing the microbial flora. The supernatant liquid is however, completely lacking in detoxifying enzymatic activity. The large proportion of toxin lost suggest that degradation of the active principe to non-fluorescent metabolites occurs. The rumen fluid of cows and sheep obtained at a slaughterhouse can hydrolyse the toxin and also, in certain cases, esterifies it to the equally toxic ochratoxin C. Cow rumen fluid obtained by oesophageal sounding does not have the latter activity but hydrolyses more intensively ochratoxin A. In this case the fraction responsible for this transformation contains mainly protozoa.