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 temp erature. in the microbiological examination of food (ingredients) if w as shown that germination during sample preparation is observed for al l bacterial spores present in these products. in standard procedures f or microbiological examination it is mentioned that the time between p reparation of the initial suspension and the mixing of dilutions and m edia shall not exceed 45 min. However, in this study if was shown that in 45 min significant numbers of spores have already germinated. Ther efore, too much time between preparation of the primary dilution and t he heat activation step led to an underestimation of the numbers of sp ores. in order to determine the proportion of spore-forming bacteria p resent 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