[Determination of the killing rate of Bacillus spores by peracetic acid]

The sporocidal properties of peracetic acid (PAA) at defined concentrations were characterized by determination of decrease in PAA after addition of D-glucose, human albumin and suspensions of spores; concentration of PAA, which inactivates 10(6)-10(7) spores of Bacillus cereus, B. subtilis, B. megaterium and B. licheniformis within 10-30 min; inactivation constant k, decimal reduction time D and the sporocidal index (mg PAA X min X ml-1) at that concentration. In contrast to albumin, the spore suspension caused relatively little reduction of PAA concentration (less than 5% at the concentrations used). B. cereus, B. subtilis and B. megaterium had similar inactivation rates with k-values in the range of 0.368 and 0.541 min-1, D-values between 4.26 min and 6.26 min at 0.2 mg/ml PAA. B. lichenformis was much more resistant showing a k = 0.345 min-1 and D = 6.66 min at 3.0 mg/ml PAA. The sporocidal index of B. lichenformis was 180 mg X min X ml-1 while the three other species had sporocidal index-values of 7 mg X min X ml-1.