Abstract
Electrochemical biosensors have become very important tools in analytical chemistry because of their advantages like accuracy, great sensitivity and easy handling. This article reports on the electrochemical detection of ethanol based on the fungus Aspergillus niger. The fungus was isolated from polyurethane waste, at a factory in India. The fungal assimilation of ethanol came to light, when detailed biochemical characterization of the fungus for alcohols, organic acids, and amino acids was studied using cyclic voltammetry. The fungus was cultured in Czepek-Dox media. A dissolved oxygen (DO) probe was fabricated using a gold cathode, a platinum counter electrode and Ag/AgCl reference electrode. The biosensor employed for the assimilation characterization was fabricated by coupling the immobilized membrane with the DO probe using dialysis tubing. A microbial dispersion containing 0.2 g (wet weight) of the organisms/mL was used for immobilization upon cellulose nitrate membrane. The membrane retaining the fungus was placed on the Teflon membrane of the oxygen electrode so that the fungus was trapped between the two membranes. The maximum detectable concentration was 35.3 ppm (v/v) and the linear range was between 1 and 32 ppm (v/v) of ethyl alcohol. By dipping the assembly with the microbe in phosphate buffer, the sensor was found to have an extended lifetime of 90 days with about 1000 determinations.
