Isolation and Characterization of Phytase-Producing Lactic Acid Bacteria for Feed Additives

Isolation of phytase-producing lactic acid bacteria and optimization of medium conditions for its production using feedstuffs for probiotics were carried out in this study. A total of 389 strains of lactic acid bacteria were isolated from 102 kinds of fruits, vegetables and fermented foods. Among them 5 strains were tested for acid-and bile salt-resistance as well as antimicrobial activities against animal pathogenic bacteria such as Escherichia coli, Staphlococcus aureus, and Bacillus cereus i. Of these strains, a strain BPL-1 producing high level of a phytase. The substrate specificity of phytase was most active against sodium phytate and inositol polyphosphate compound. The optimal composition of culture medium for the cell growth and phytase activity was 2%(w/v) glucose as a carbon source, 1.5%(w/v) yeast extract as a nitrogen source, and manganese sulfate and ammonium citrate as inorganic salts. The phytase from strain BPL-1 was showed optimum activity at 37℃, pH 7.0. The phytase activity was stable up pH 5.0, 7.0 and 11.0. The Km valueof phytase for the sodium phytate was 0.82 mM.