Yeast cells sucrose biosensor based on a potentiometric oxygen electrode

A new microbial biosensor based on an immobilised microorganisms (Saccharomyces cerevisiae) and a potentiometric oxygen electrode is described. Determination is based on the respiratory activity of the microorganism in presence of different sugars (sucrose and glucose). A response time of ca. 4 min for the steady-state method and 2 min for the initial slope method was obtained. Potentiometric detection has the advantage of an extended calibration range and a low detection limit. The calibration curve for sucrose was linear in the range 1×10⁻⁵ to 3×10⁻² M. This biosensor was used for selective monitoring of sucrose in the presence of glucose, using a second anti-interference enzymatic layer with glucose oxidase (GOD) and catalase (CAT). Interference of glucose in the determination of sucrose decreases from 15% for a microbial biosensor to a maximum 3.5% for the hybrid biosensor. The hybrid biosensor was used to determine sucrose in soft drinks. A good correlation between the results for the biosensor and a spectrophotometric method with dinitrosalicylic acid was achieved.