Membrane Filtration of Milk for Counting Spores of Clostridium tyrobutyricum

Abstract

Estimation of Clostridium 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 Clostridium tyrobutyricum spores at the high sensitivity required by the spoilage capacity of this microorganism in Emmenthal-type cheese. Incubation of milk with .072% trypsin at 55°C for 15 min, followed by filtration under three bars (30.6 Mg/m2) pressure through .8-μm porosity membrane filtration, permitted filtration of volumes larger than 300 ml, although with high standard deviation 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 Clostridium tyrobutyricum spores in milk. © 1984, American Dairy Science Association. All rights reserved.