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Production of lactobionic acid and sorbitol from lactose/fructose substrate using GFOR/GL enzymes from Zymomonas mobilis cells: A kinetic study

Paper ID Volume ID Publish Year Pages File Format Full-Text
17404 42666 2011 9 PDF Available
Title
Production of lactobionic acid and sorbitol from lactose/fructose substrate using GFOR/GL enzymes from Zymomonas mobilis cells: A kinetic study
Abstract

In this work, we have investigated the kinetics of the biotechnological production of lactobionic acid (LBA) and sorbitol by the catalytic action of glucose–fructose oxidoreductase (GFOR) and glucono-δ-lactonase (GL) enzymes. The cells of bacterium Zymomonas mobilis ATCC 29191 containing this enzymatic complex were submitted to permeabilization and reticulation procedures. The effect of the concentration of substrates on the rate of product formation using a mobilized cell system was investigated. The application of higher fructose concentration seems to not affect the initial rate of formation of the bionic acid. Under conditions of low initial concentration of lactose, the experimental kinetic data of the bi-substrate reaction were modelled by assuming a rate equation of the classical ping-pong mechanism. The found kinetic parameters displayed a low affinity of the GFOR enzyme for both substrates. The enzymatic system did not exhibit normal Michaelis–Menten kinetics in response to a change of concentration of lactose, when fructose was held constant, presenting a sigmoid relationship between initial velocity and substrate concentration. A rate equation based on Hill kinetics was used to describe the kinetic behaviour of this enzyme-substituted reaction at higher lactose concentrations. The results from batch experiments using immobilized cells within Ca-alginate beads revealed that there is no pronounced occurrence of mass transfer limitations on LBA production for beads with 1.2 mm in average diameter. This discussion aids for defining the best operating conditions to maximize the productivity for LBA and sorbitol in this bioconversion and also for reducing the complexity of downstream separation processes.

Keywords
Sorbitol; Lactobionic acid; GFOR/GL enzymes; Ping-pong mechanism; Bi-substrate reaction
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Production of lactobionic acid and sorbitol from lactose/fructose substrate using GFOR/GL enzymes from Zymomonas mobilis cells: A kinetic study
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Publisher
Database: Elsevier - ScienceDirect
Journal: Enzyme and Microbial Technology - Volume 49, Issue 2, 10 July 2011, Pages 183–191
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us