Inactivation Kinetics of Escherichia coli by Pulsed Electron Beam

Abstract

A novel and compact low-energy (keV) high-power pulsed electron beam (e-beam) that utilizes a secondary emission electron gun (SEEG) was designed and constructed. Escherichia coli JM 109 at a concentration of 10(6) CFU/mL was spread-plated on Luria-Bertani (LB) medium and subjected to the SEEG e-beam. The e-beam was administered as 1 or 5 pulses. The duration of a single pulse was constant at 5 micros, e-beam current density was constant at 25 mA/cm2, and e-beam energy varied between 60 and 82.5 keV. Following treatment with the SEEG e-beam, survivors of the irradiated E. coli samples were enumerated by a standard 10-fold dilution and spread-plated. The survivor curves were plotted on logarithmic scale as a function of e-beam dose. The D10-values were calculated as a negative reciprocal of the slope of the survivor curves. The D10-values for E. coli inactivated with 1- and 5-pulse SEEG e-beam were 0.0026 and 0.0217 Gy, respectively. These D10-values were considerably lower than published D10-values for E. coli inactivated with conventional high-energy continuous e-beam, likely due to shorter exposure time (t), greater current density (J), and a pulse mode of the SEEG e-beam. The SEEG e-beam showed promising results for microbial inactivation in a nonthermal manner; however, due to low energy of the SEEG e-beam, current applications are limited to surface decontamination. The SEEG e-beam may be an efficient processing step for surface inactivation of food-borne pathogens on ready-to-eat products, including fresh and leafy vegetables.

Application of electron beam to inactivate Salmonella in food: Recent developments

“…7. A diagram of experimental secondary emission electron gun (SEEG) e-beam including decontamination chamber, wire ion plasma source, secondary emission electron gun, and power systems (Adapted from Chalise et al, 2007).…”

“…7). The SEEG e-beam has been shown to be effective at reducing non-pathogenic E. coli (Chalise et al, 2004;Chalise, Hotta, Matak and Jaczynski, 2007) and Bacillus subtilis in vegetative and spore forms (Rahman et al, 2006). However, the SEEG e-beam has not been tested yet for its efficacy against typical foodborne pathogens in different food matrices.…”

Brucellosis: The case for live, attenuated vaccines

“…In fact, DNA vaccines have provided some promising results using cocktails of up to three antigens [26]. Furthermore, the use of heat-killed organisms may be a result of antigen deformation due to the killing method rather than the absence of viable organism suggesting that other approaches such as irradiation may prove useful [27, 28]. …”

Radioresistance development of DNA repair deficientEscherichia coliDH5α in ground beef subjected to electron beam at sub-lethal doses

“…Ionising radiation effectively inactivates microorganisms including foodborne pathogens (Farkas 1998, Black and Jaczynski 2006, 2007, Chalise et al 2007, O'Bryan et al 2008, Arvanitoyannis et al 2009, Arvanitoyannis and Stratakos 2010, James et al 2010. Therefore, application of ionising radiation to food processing enables food manufacturers to increase microbial food safety and extend shelf-life of food products.…”