Methanogenic activity measurements by the MAIA biosensor: instructions guide

The MAIA (Methanogenic Activity and Inhibition Analyser) titration biosenso r is a pH-stat where the alkalinity produced by acetoclastic methanogens is neutralised by acid addition. By measuring the titrant flowrate the activi ty of the acetoclastic methanogens can be calculated, Numerous tests, carri ed out in Italy (Rozzi et at., 2000) and South Africa (Murugen et al., 1999 ), showed that this instrument makes it possible to evaluate maximum activi ty, inhibition and kinetics of acetoclastic methanogens more easily and acc urately than existing volumetric or manometric procedures, e.g. Valcke and Verstraete (1983) and Owen et al. (1979). Notwithstanding its conceptual si mplicity, the apparatus requires careful handling in order to yield accurat e and reliable results. This paper presents the main operating problems found while using this inst rument and describes the possible solutions. It can therefore be defined as a short instruction handbook for the use of the MAIA biosensor.