increase in the extent of germination was observed when spores from all five food poisoning isolates were incubated at 55, 60 or 65 C with the AK mixture in the same buffer. The effect was most significant when spores were incubated at 55 C, reaching an average of 76% germination for all food poisoning isolates with the exception of strain FD1041, for which only 40% of spores became phase dark (data not shown). The release of DPA, an early stage of spore germination, is barely detectable by phase microscopy (see below) and reduces spore heat resistance.