A process for stabilizing glutamate dehydrogenase (GDH) from a bacterium of the Clostridium genus, in an aqueous solution, in order to maintain the antigenic properties thereof, includes the step of mixing the glutamate dehydrogenase and a stabilizing composition which is a carboxylic acid having a carbon-based chain of at least 3 carbon atoms and comprising at least 2 —COOH groups, or a salt thereof. GDH compositions thus stabilized and a method of detecting the presence of bacteria of the Clostridium genus are also disclosed.