Development of electrochemical microbial biosensor for ethanol based on Aspergillus niger

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 eth anol based on the fungus Aspergillus niger. The fungus was isolated from po lyurethane waste, at a factory in India. The fungal assimilation of ethanol came to light, when detailed biochemical characterization of the fungus fo r alcohols, organic acids, and amino acids was studied using cyclic voltamm etry. 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 c haracterization was fabricated by coupling the immobilized membrane with th e 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 fun.-us was placed on the Tefl on membrane of the oxygen electrode so that the fungus was, trapped between the two membranes. The maximum detectable concentration was 35.3 ppm (nu/n u) and the Linear range was between 1 and 32 ppm. (nu/nu) of ethyl alcohol. By dipping the assembly with the microbe in phosphate buffer, the sensor w as found to have an extended lifetime of 90 days with about 1000 determinat ions.