Membrane Filtration of Milk for Counting Spores of Clostridium tyrobutyricum

Open Access
Publisher Website
Google Scholar
Abstract
Estimation of C. tyrobutyricum spores in milk by most probable number, after anaerobic incubation in a liquid medium, is not rapid, sensitive nor reproducible. Membrane filtration appears to be the only technique able to concentrate microorganisms in milk sufficiently for detection of C. tyrobutyricum spores at the high sensitivity required by the spoilage capacity of this microorganism in Emmenthal-type cheese. Incubation of milk with 0.072% trypsin at 55.degree. C for 15 min, followed by filtration under 3 bars (30.6 mg/m2) pressure through 0.8-.mu.m porosity membrane filtration, permitted filtration of volumes larger than 300 ml, although with high SD and important seasonal variation. The test of other enzymes gave lower results. Viability was not impaired, and spore recovery was good under these conditions of treatment and filtration. This technique seems practical for enumeration of C. tyrobutyricum spores in milk.