The strains were cultivated in MRS broth containing 0.1% (w/v) of sodiumphytate (Sigma, France) and either 0.2 or 2% (w/v) glucose (Sigma,France). Phytase activity was determined according to the method of Fiske and Subbarow (1925). One unit (U) was defined as the amount of enzyme required to liberate 1nmol of phosphate from sodium phytate per min under the assay conditions. The results are expressed as U/ml.