Kinetic studies on urea hydrolysis by immobilized urease in a batch squeezer and flow reactor

Abstract

The immobilization of urease on the reticulated polyurethane foam, and the kinetic phenomenon of urea hydrolysis by the resulting immobilized urease in both batch squeezer and circulated flow reactors were studied. Urease was immobilized with bovine serum albumin and glutaraldehyde on polyurethane foam support of 7 to 15 mum thickness. The residual apparent activity of urease after immobilization was about 50%. The good hydrodynamic property and flexibility of polyurethane foam were retained in solution after immobilization. A modified biofilm reactor model was used to describe the kinetic phenomenon of urea hydrolysis in both batch squeezer and circulated flow reactors. The characteristic parameters of the reactor model for both bioreactors were obtained by combining the Rosenbrock optimization method, the Rungs-Kutta method, and the Newton-Raphson method. The best-fit results were in good agreement with the experimental data. This study suggests another application of polyurethane foam in enzyme immobilization and immobilized enzyme reactors, which offers potential for practical applications in various bioreactors.

Flow Injection Immunoanalysis Based on a Magnetoimmunosensor System

“…The enzymatic activity retained by the magnetic particles is appraised by injecting substrate (urea) to the main channel. Urea is hydrolyzed by the enzyme according to the reaction and, if a buffering system formed by NH 3 and NH 4 + is considered, the pH in the injection zone will vary according to pH = p K a + log([NH 3 ]/[NH 4 + ]). If [NH 4 + ] is kept constant in the carrier channel and at a value higher than [NH 3 ], then the enzyme reaction will produce a rise of pH that will be a linear function of log[NH 3 ].…”

Epoxy-derived pHEMA membrane for use bioactive macromolecules immobilization: Covalently bound urease in a continuous model system

“…2) show that the mem- EPOXY-DERIVED pHEMA MEMBRANE brane has a highly open pore structure, which may lead to high internal surface area (implying high immobilization capacity). 4,[12][13][14][15]25,26 Analysis of wash solutions showed that the immobilization process was irreversible.…”

A new process for the treatment of fertilizer effluent using immobilized urease

“…Immobilized microorganism and enzyme offer a considerable reduction in BOD and COD level facilitating a continuous operation [2][3]. But immobilized enzyme technology, to become commercially viable in industrial applications, parameters such as cost of getting purified enzyme, carrier matrix and coupling techniques are some of the important factors to be considered in detail [3][4][5][6].…”