Applied Sciences (Mar 2024)

Microwave Oven Application for the Preparation and Sterilization of Microbiological Culture Media: A Feasible Method with An Adapted Water Bath and Perforable Cap

  • Ines Terrones-Fernandez,
  • Lourdes Rodero-De-Lamo,
  • Asunción López,
  • Sara Peiró,
  • Daniel Asensio,
  • Robert Castilla,
  • Pedro Javier Gamez-Montero,
  • Nuria Piqué

DOI
https://doi.org/10.3390/app14062340
Journal volume & issue
Vol. 14, no. 6
p. 2340

Abstract

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There is currently increased interest in the use of alternatives to autoclaved culture media, in order to maintain the properties of the media, while saving energy and time. In this study, we assess a new system for culture media preparation, using a conventional microwave with a water bath and a glass bottle with a rubber cap that allows depressurization. Sterilization, using the proposed system (1000 W, 3 to 20 min), was compared with autoclaving for the preparation of tryptone soy agar (TSA), tryptone soy broth (TSB), Sabouraud 4% dextrose agar (SDA), and violet red bile glucose agar (VRBG). Microwave exposure for 7 min yielded sterile TSA plates. The productivity of both sterilization methods was assessed using the pour plate method, and significant increases in the growth of certain micro-organisms after using a microwave were observed for every culture medium, especially those that were sterilized by boiling (VRBG). The kinetics of microbial destruction showed that Escherichia coli and Bacillus subtilis spores were destroyed after 3 and 7 min in a microwave, respectively, while three decimal reductions were obtained for Geobacillus stearothermophilus spores after 15 min in an autoclave. This new sterilization method could be a feasible, rapid, and economical method to prepare microbiological media, with a quality similar to that obtained through autoclaving.

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