量研学術機関リポジトリ「QST-Repository」は、国立研究開発法人 量子科学技術研究開発機構に所属する職員等が生み出した学術成果（学会誌発表論文、学会発表、研究開発報告書、特許等）を集積しインターネット上で広く公開するサービスです。 Welcome to QST-Repository where we accumulates and discloses the academic research results(Journal Publications, Conference presentation, Research and Development Report, Patent, etc.) of the members of National Institutes for Quantum Science and Technology.
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Bacillus subtilis is known as Gram-positive, rod-shaped, aerobic, spore-forming bacterium that is naturally found in soil. The spore is resistant to environmental factors such as heat, desiccation, chemical, and radiation. Besides, ionizing radiation induces DNA damages including single-strand breaks and double-strand break and generates reactive oxygen species which also induces DNA strand breaks. Ion beams have a high LET and give DNA damage containing double-strand break locally (clustered damage) than gamma rays do. Recently, ion beams have been used for mutation breeding in biological objects including rice, flowers and bacteria. Mutations in the RNA polymerase β subunit of the B. subtilis, encoded by rpoB gene, related to rifampicin resistance and can be genareted by irradiation method. In this work, we utilized ion beams to check mutation induction for rifampicin to characterize the mutation by high LET ion beam irradiation to B. subtilis spores. The initial spore germination process seemed not to be affected by ion–beam irradiation. Outgrowth phase after the germination became longer with the irradiation dose as well as 60Co gamma-rays. These results suggest that damaged sites in spores are similar between gamma- and ion-beam irradiations. By the screening of RifR mutants, a certain number of RifR mutants was obtained for 4He2+, 60Co, 40Ar13+ irradiation within lower doses showing relatively lower lethality.
Effect of Ion Beams and Gamma Rays Irradiation on Mutation Induction in Bacillus subtilis Spores
