Some bacteriological aspects of commercially sterilized milk: II. Type of sporeforming bacteria isolated

Cultures of sporeforming bacteria isolated from commercially sterilized milk were examined and seasonal variations in the incidence of B. subtilis / B. licheniformis strains were apparent which may account for the increased rate of spoilage at 30° C. during the winter. B. subtilis was the most common mesophilic sporeformer isolated, and under favourable conditions it produces rapid digestion of milk. Thermophilic sporeformers are frequently present, and usually produce a firm acid clot in milk held at temperatures favourable for their growth. The classification of the thermophiles isolated is uncertain and a review of the classification of the aerobic thermophilic sporeformers in general is required. Cl. thermosaccharolyticum , a gas-producing thermophile, was isolated from sterilized milk.