Influence of the sporulation temperature on the impact of the nutrients inosine and L-alanine on Bacillus cereus spore germination

The effect of sporulation temperature on Bacillus cereus spore germination triggered by the nutrient germinants inosine and L-alanine was investigated. The germination (expressed as % A(600m), fall) of heat-activated spores of B. cereus strain ATCC14579 produced at 20 and 37 degrees C, and of psychrotrophic strains LM9 and D 15 produced at 15 and 37 degrees C was followed in a germination buffer containing inosine at concentrations between 0.01 and 10 mmol 1(-1), or L-alanine between I and 100 mmol 1-1. Spores wet-heat resistance at 90 degrees C was also determined. Spores of the three strains produced at the lowest temperatures generally showed a higher germination capacity in response to both inosine and in L-alanine than those produced at 37 degrees C, and were also more susceptible to heat. Low sporulation temperature is confirmed as a detrimental factor to B. cereus spore wet-heat resistance, and conversely gave spores with a sensitivity to the nutrient germinants inosine and L-alanine higher than that of spores formed close to the maximal sporulation temperature. (c) 2007 Elsevier Ltd. All rights reserved.