Date of Award
Master of Science
Department of Engineering Physics
Larry W. Burggraf, PhD.
Samples containing 107 spores of Bacillus anthracis (Ba) Sterne in water were irradiated with 267nm UVC using small LEDs and, for comparison, Cs-137 gammas. Before irradiation, 1mM L-Met and D-Met were added to solution and remained through germination. Following UV irradiation, minimal media was added and the spores were incubated for various times. Spore viability was quantified as lag time of the spore using SYTO 16 photoluminescence. Fluorescence was compared between irradiated and unirradiated experiments, demonstrating a delay in outgrowth for irradiated samples. D-Met samples showed increased damage repair, while L-Met spores expressed delayed outgrowth for unirradiated and irradiated spores. L-methionine and D-methionine were introduced to Ba during sporulation and adherence was verified using CD spectrometry. 1mM DP1 was added to Ba before irradiation. CFUs were collected after gamma irradiation for 1000Gy increments for 0-8000Gy. The gamma doses corresponding to 1-log10 inactivation for the four spore types were: approximately 5000Gy for control and D-methionine; more than 8000Gy for DP1 spores; inconclusive for L-methionine. DP1 spores showed a significant resistance to damage, while D-Met spores showed minimal change in survival. L-Met spores clumped readily and produced unsatisfactory results. The gamma dose rate used doubled the dose expected to inactivate 90% of Ba spores.
DTIC Accession Number
Harris, Cameron N., "The Efficiency of Methionine as a Radioprotectant of Bacillus anthracis for Cell Viability and Outgrowth Time after UVC and Gamma Irradiation" (2015). Theses and Dissertations. 81.