title: Adsorption immobilization of Escherichia coli phytase on probiotic Bacillus polyfermenticus spores.
abstract: The immobilization of enzymes on edible matrix supports is of great importance for developing stabilized feed enzymes. In this study, probiotic Bacillus spores were explored as a matrix for immobilizing Escherichia coli phytase, a feed enzyme releasing phosphate from phytate. Because Bacillus spore is inherently resistant to heat, solvents and drying, they were expected to be a unique matrix for enzyme immobilization. When mixed with food-grade Bacillus polyfermenticus spores, phytases were adsorbed to their surface and became immobilized. The amount of phytase attached was 28.2 ± 0.7 mg/g spores, corresponding to a calculated activity of 63,960 U/g spores; however, the measured activity was 41,120±990.1U/g spores, reflecting a loss of activity upon adsorption. Immobilization increased the half life (t(1/2)) of the enzyme three- to ten-fold at different temperatures ranging from 60 to 90°C. Phytase was bound to the spore surface to the extent that ultrasonication treatment was not able to detach phytases from spores. Desorption of spore-immobilized phytase was only achieved by treatment with 1M NaCl, 10% formic acid in 45% acetonitrile, SDS, or urea, suggesting that adsorption of phytase to the spore might be via hydrophobic and electrostatic interactions. We propose here that Bacillus spore is a novel immobilization matrix for enzymes that displays high binding capacity and provides food-grade safety.
authors: Industrial Biotechnology and Bioenergy Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 111 Gwahangno, Yusong, Daejeon 305-333, Republic of Korea.
authors: Eun-Ah
authors: EA
authors: Cho
authors: Eui-Joong
authors: EJ
authors: Kim
authors: Jae-Gu
authors: JG
authors: Pan
mesh_terms: D010832:6-Phytase / Q000737:chemistry; D000327:Adsorption; D001407:Bacillus; D004795:Enzyme Stability; D004800:Enzymes, Immobilized / Q000737:chemistry; D004926:Escherichia coli / Q000201:enzymology*; D005524:Food Technology; D019936:Probiotics; D013171:Spores, Bacterial
chemical_list: D004800:Enzymes, Immobilized; D010832:6-Phytase