Disinfection of Vegetative Cells of Bacillus anthracis
Technical Report,01 Nov 2012,31 Oct 2014
Edgewood Chemical Biological Center APG United States
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Disinfection kinetics of vegetative cells of Bacillus anthracis in water with free available chlorine FAC 2 mgL and monochloramine MC 2 mgL were established in this study. FAC disinfection was performed in chlorine demand-free phosphate buffer at pH 7 and 8 at two temperatures 5 and 25 deg. C. MC disinfection was performed in normal phosphate buffer at pH 8 at both temperatures. FAC was more effective than MC in causing cell death, which was more rapid at 25 deg. C than at 5 deg. C at both pH 7 and 8. For MC disinfection, the cell inactivation rate was more rapid at 2 deg. C. The disinfection kinetics were rapid within the first 5 min, followed by a slow cell inactivation. The results were complicated by the varying number of spores present in the test inoculums. Although protocols were developed and implemented to minimize the spore number, varying numbers of spores were observed in the different runs. The presence of spores also resulted in high variability,especially at sublethal exposure levels. Our efforts were focused on developing a new culture recipe RVLS to ensure aminimal number of spores and to confirm the absence of spores in the sporulation-minus strain spo- of B. anthracis.