Immobilization of Phytase Producing Probiotics in Shrimp Chitosan Cross-linked by Zinc Oxide Nanoparticles and Assay its Antibacterial Activity

Background and objective: Phytase is used in human and poultry additives. This enzyme is mostly produced by Aspergillus niger which is a plant pathogen. Phytase from probiotics is a good candidate for the food supplements. Materials and methods: Bacillus coagulans, as a probiotic, was used for phytase and phosphatase activities on phytin agar and Pikovskayas Agar. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis and zymogram analyses of the extracted phytase enzyme were carried out. Probiotic cells with phytase activity were immobilized on chitosan extracted from shrimp shells and the efficiency was investigated and analyzed using scanning electron microscopy and Fourier transform infrared. Results and conclusion: In this study, Bacillus coagulans showed intracellular phytase activities from broken cells with Soluble Index of 2.5 on phytase specific media. Iron and zinc oxide nanoparticles accelerated the enzyme activity by 25%. Cells were precipitated using ZnO-chitosan nanoparticles and the enzyme activity was investigated on gels. Chelation of chitosan-metal ion increased the positive charge density of chitosan which was expected to enhance adsorption of zinc and teichoic acid on Gram-positive Bacillus coagulans; approved by SEM and FTIR. Cells immobilized on ZnO-chitosan promoted the enzyme activity by 28,800 U ml-1 gel. The entrapped cells were resistance to high temperature and pH. This complex not only included activities against Streptococcus agalactiae, but also dissolved insoluble phosphate and phytin, which has made this complex a good candidate for use as additive in human and animal foods.