A RAPD-based survey of thermophilic bacilli in milk powders from different countries.

Twenty-eight milk powders from 18 different countries were examined for the number and type of contaminating thermophilic bacilli. Of 742 isolates examined, 96.8% were assigned to the same strains of bacilli as previously found in New Zealand powders. The dominant isolate was Anoxybacillus flavithermus strain C followed by Bacillus licheniformis strain F. The former was also prevalent in New Zealand powders and the results demonstrate that A. flavithermus represents a widespread contaminant, seemingly ubiquitous in factories producing milk powder. The presence of thermophilic strains of Geobacillus stearothermophilus and to a lesser extent of Bacillus subtilis in milk powders was reconfirmed.