Analyse bacteriologique de l'eau par mesure potentiometrique de la reduction de l'acide lipoique

A simple potentiometric technique to detect and enumerate the bio-indicators of water contamination is described. The technique consists in measuring the redox potential of a specific culture medium saturated with oxygen where bacteria are incubated in presence of lipoic acid (LA). These micro-organisms reduce LA to dihydrolipoic acid, giving rise to an important potential drop in the system. This potentiometric "signal" reveals the presence of active metabolic bacteria in the medium. The major assets of potentiometric measurements in presence of LA lies in the reliability and intelligibility of the results (the redox phenomenon being qualitatively and quantitatively studied), associated to a very simple technology. Futhermore, this technique is perfectly adaptable to other media other than fresh water, such as sea water or biological fluids (blood, urine) and food stuffs (milk).