Sterilization effects of UV laser irradiation on Bacillus atrophaeus spore viability, structure, and proteins

spores are highly resistant to toxic chemicals and extreme environments. Because some species threaten public health, spore inactivation techniques have been intensively investigated. We exposed spores to a 266 nm Nd:YVO laser at a laser power of 1 W and various numbers of scans. As a result, the UV laser reduced the viability of spores. Although the outer coat of spores remained intact after UV laser irradiation of 720 scans, damage inside the spores was observed. Spore proteins were identified by matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry during the course of UV laser irradiation. Photochemical and photothermal processes are believed to be involved in the UV laser sterilization of spores. Our findings suggest that a UV laser is capable of sterilizing spores.