An ethanol biosensor based on a bacterial cell-immobilized eggshell membrane

An ethanol biosensor was fabricated based on a Methylobacterium organophilium-immobilized eggshell membrane and an oxygen (O₂) electrode. A linear response for ethanol was obtained in the range of 0.050-7.5 mmol/L with a detection limit of 0.025 mmol/L (S/N = 3) and a R.S.D. of 2.1%. The response time was less than 100 s at room temperature and ambient pressure. The optimal loading of bacterial cells on the biosensor membrane is 40 mg (wet weight). The optimal working conditions for the microbial biosensor are pH 7.0 phosphate buffer (50 mmol/L) at 20-25°C. The interference test, operational and storage stability of the biosensor are studied in detail. Finally, the biosensor is applied to determine the ethanol contents in various alcohol samples and the results are comparable to that obtained by gas chromatographic method and the results are satisfactory. Our proposed biosensor provides a convenient, simple and reliable method to determine ethanol content in alcoholic drinks.