The associative growth of Bacillus cereus and Streptococcus lactis in milk

It has been found that when three strains of Bacillus cereus are grown in turn with each of two strains of Streptococci lactis and two strains of the coli-aerogenes group, the growth of the spore-formers is neither suppressed nor stimulated. It has been confirmed, however, that the spore-former is unlikely to develop if the milk is held at 15°C. or below. Broken cream results if marked growth of B. cereus occurs. A nisin-producing strain of Str. lactis did not retard the development of the spore-former in milk, but after initial increase the numbers of B. cereus decreased. Broken cream was not prevented.