Bacterial eradication by a low-energy pulsed electron beam generator.

Low-energy electron beams (LEEB) are a safe and practical sterilization solution for in-line industrial applications, such as sterilizing medical products. However, their low dose rate induces product degradation, and the limited maximal energy prohibits high-throughput applications. To address this, we developed a low-energy 'pulsed' electron beam generator (LEPEB) and evaluated its efficacy and mechanism of action. Bacillus pumilus vegetative cells and spores were irradiated with a 250 keV LEPEB system at a 100 Hz pulse repetition frequency and a pulse duration of only 10 ns. This produced highly efficient bacterial inactivation at a rate of >6 log, the level required for sterilization in industrial applications, with only two pulses for vegetative bacteria (20 ms) and eight pulses for spores (80 ms). LEPEB induced no morphological or structural defects, but decreased cell wall hydrophobicity in vegetative cells, which may inhibit biofilm formation. Single- and double-strand DNA breaks and pyrimidine dimer formation were also observed, likely causing cell death. Together, the unique combination of high dose rate and nanosecond delivery of LEPEB enable effective and high-throughput bacterial eradication for direct integration into production lines in a wide range of industrial applications.