Isolation and identification of anaerobic contaminants from a machine for producing processed cheese.

Some bacteria of the genus Clostridium can contaminate milk. These bacteria can cause "the late gas" or "late blowing" defect in the cheese if this is made with milk containing such contaminants. In this study, six samples from a processed cheese contaminated in a manufacturing machine were analysed. Out of 60 strains studied, 30 were classified as Clostridium tyrobutyricum, 20 as Clostridium butyricum, and 10 as Desulfotomaculum ruminis.