engleski

Validation of effects of γ-irradiation on characteristics of standard microbiological media

Gamma irradiation method is efficient, safe and fast method for inactivation of all biological contaminants at all stages of their life cycle. This method is based on the ability of high-energy photons generated by radioactive 60Co to induce chemical DNA damage in biological contaminants such as insects, moulds, yeasts and bacteria. Therefore, γ-irradiation finds its use in sterilization of different materials such as medical supplies and pharmaceuticals and in food quality preservation. The aim of this research work was to investigate the physico-chemical parametars and microbiological characteristics of Tryptone soya and Sabouraud Dextrose agar media on Petri dishes after irradiation in dependence on the irradiation dose. Microbiological media (20 Petri dishes) packed in thermalshrinking foil were put in cardbox in the presence of biological indicators (spores of Bacillus pumilus). The three irradiation cycles were performed on the panoramic 60Co source at the Ruđer Bošković Institute. Dosimetry were established with the ethanol- chlorobenzene dosimetry system (ISO/ASTM 51538: 2017). Quality control of microbiological media was perfomed before and after irradiation according HRN EN ISO 11133. Physico-chemical parameters (appearance, color, homogeneity, agar consistency) and microbiological characteristics of culture media (sterility and productivity) were tested. Since the results of performed tests meet the requirements in accordance of guidelines of EU and corresponding standards we recommend these plates to be used for microbiological methods, validation of aseptic procedures control of safe operation under clean conditions. This research is result of collaboration of the Radiation Chemistry and Dosimetry Laboratory and the Department of Clinical Microbiology, Andrija Štampar Teaching Institute of Public Health in Zagreb

microbiological tests ; radiation dose ; Sabouraud Dextrose agar ; Tryptone soya agar

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