GERMINATION OF BACTERIAL-SPORES DURING SAMPLE PREPARATION

The effect of environmental conditions on the germination of Bacillus cereus was investigated Germination was affected to varying extent by strain type, complexity of the medium, presence of germinants and temperature. in the microbiological examination of food (ingredients) if was shown that germination during sample preparation is observed for all bacterial spores present in these products. in standard procedures for microbiological examination it is mentioned that the time between preparation of the initial suspension and the mixing of dilutions and media shall not exceed 45 min. However, in this study if was shown that in 45 min significant numbers of spores have already germinated. Therefore, too much time between preparation of the primary dilution and the heat activation step led to an underestimation of the numbers of spores. in order to determine the proportion of spore-forming bacteria present as spores, the time between preparation of the primary dilution and the heat activation step should be as short as possible (<10 min) and the temperature of diluents during the analysis should be as low as possible (e.g in melting ice). (C) 1995 Academic Press Limited