A plasma reactor for experimental investigation of sterilization processes: Preliminary results on Escherichia coli

Plasma process is a promising physical method for sterilization. Due to the lack of suitable plasma diagnostics, installed in the reactors, a general lack of knowledge happens about the gas-phase chemical composition and the influence of operating parameters. The same lack of knowledge happens in case of gas plasma generated from different gases, candidates for sterilization purposes. The aim of this work is to understand the role of different agents acting in the sterilization process, evaluate the effectiveness of different precursor gases and validate the plasma reactor dedicated. A plasma reactor, equipped with an extended set of plasma diagnostics is dedicated to the understanding the role of different agents of gas plasma sterilization process. A microbiological investigation is carried out to evaluate the efficiency of the steps of the process on cultures of Escherichia coli, using both hydrogen peroxide and argon. The effects on the colonies of Escherichia Coli are assessed in terms of species present in the chamber, acquiring the spectra resulting from the exposure of the Petri dish to sterilization. With regard to the sterilization action of Peroxide and Argon plasma, CFUs are counted for each significant point of the cycle and survival curves are provided. Differences emerge between Peroxide and Argon plasma, for action mechanisms and sterilization time. The survival curves show a more effective sterilizing action of Argon plasma. A validation is necessary by an appropriate statistic and by considering more resistant microorganisms. Reactor will be used to evaluate different precursor gases and microorganisms. The use of noncorrosive and non-irritating gas, such as argon, for sterilization purpose implies a simplification of the plant equipment. It would be possible to remove the components for the vaporization and concentration of peroxide, and to eliminate the management of the boxes containing discarded peroxide, managed to date as hazardous wastes and to reduce significantly the risk for health professionals.