A robust microbial biosensor was constructed from a bionanocomposite prepared by a direct mixing of bacterial cells of Gluconobacter oxydans and carbon nanotubes with ferricyanide employed as a mediator for enhanced sensitivity of ethanol oxidation. A successful integration of the device into flow injection analysis mode of operation provided a high sensitivity of detection of (74 +/- A 2.7) mu A mM(-1) cm(-2), a low detection limit of 5 mu M and a linear range from 10 mu M up to 1 mM. A short response time of the biosensor allowed a sample throughput of 67 h(-1) at 0.3 ml min(-1). The biosensor exhibited high operational stability with a decrease in the biosensor response of 1.7% during 43 h of continuous operation. The device was used to analyse ethanol in fermentation samples with a good agreement with a HPLC method.