Abstract: Apparatus for use in detecting micro-organisms in any one of a plurality of samples of a liquid, such as a food or drink product, e.g. for control of production, comprises a plurality of containers (11) for the sample and a container-mounting member (10) to receive and locate each of the containers, each container being provided with a first electrode of a noble metal (16) and a second electrode, which may be constituted by the body of the container (11), insulated from the first and of a different metal. The container-mounting member (10) is provided with separate contacts (12) and leads for each of the noble metal electrodes (16) and with contacts (922) connected to a common lead for each of the second electrodes.