Hybrid biosensor for the determination of lactose

Area of Science:

• Biotechnology
• Biosensor Development
• Enzyme Engineering

Background:

• Genetically modified Escherichia coli (E. coli) K-12 recombinant PQ-37 exhibits hyperproduction of beta-galactosidase when exposed to genotoxic agents.
• Glucose oxidase (EC 1.1.3.4) is a key enzyme for electrochemical biosensing applications.

Purpose of the Study:

• To construct a hybrid biosensor for lactose detection by combining E. coli and glucose oxidase.
• To evaluate the performance and stability of the developed lactose biosensor.

Main Methods:

• Coimmobilization of E. coli cells and glucose oxidase onto a nylon network using glutaraldehyde.
• Fixation of the biocatalytic layer to a Clark oxygen electrode.
• Optimization of sensor response by testing pH, temperature, and beta-galactosidase activator concentrations.

Main Results:

• The hybrid sensor successfully analyzed lactose content in milk products without sample pretreatment.
• Lactose measurements obtained with the hybrid sensor showed good agreement with conventional photometric methods.
• The sensor demonstrated high operational stability with a half-life of 30 days and a standard relative deviation below 3%.

Conclusions:

• The developed hybrid lactose biosensor is a sensitive, stable, and accurate tool for lactose determination in food analysis.
• The biosensor's performance is not significantly affected by common milk matrix components, simplifying sample preparation.
• This technology offers a promising alternative for routine lactose monitoring in the dairy industry.