Bioelectrical conversion in sensors with living cells.

Bacterial metabolism can drive various processes with biotechnological significance, like in the case of biosensors for probing organic compounds, or in biofuel cells. Here we present some of our results connected with the construction of a bacterial electrode with Pseudomonas sp. for probing glucose in body fluids, and those related to biofuel cells with anaerobic bacteria (Clostridium sp.). The output of the bioselective electrode linearly indicates glucose concentrations in the 2.5 x 10(-5)-1.25 x 10(-4) M domain, with a sensitivity limit of 10(-5) M. The time constant is 10 min, and it works for more than ten days. The amperometric response of biofuel cells with Clostridium sp. offers the electrical image of the state of the bacterial culture itself, thus being a promising tool for the automated control of the bacterial suspensions used in fermentative reactors.