Improvement of Biological Indicators by Uniformly Distributing Bacillus subtilis Spores in Monolayers To Evaluate Enhanced Spore Decontamination Technologies

摘要

Novel decontamination technologies, including cold low-pressure plasma and blue light (400 nm), are promising alternatives to\udconventional surface decontamination methods. However, the standardization of the assessment of such sterilization processes\udremains to be accomplished. Bacterial endospores of the genera Bacillus and Geobacillus are frequently used as biological indicators\ud(BIs) of sterility. Ensuring standardized and reproducible BIs for reliable testing procedures is a significant problem in industrial\udsettings. In this study, an electrically driven spray deposition device was developed, allowing fast, reproducible, and homogeneous\udpreparation of Bacillus subtilis 168 spore monolayers on glass surfaces. A detailed description of the structural\uddesign as well as the operating principle of the spraying device is given. The reproducible formation of spore monolayers of up to\ud5x10⁷ spores per sample was verified by scanning electron microscopy. Surface inactivation studies revealed that monolayered\udspores were inactivated by UV-C (254 nm), low-pressure argon plasma (500 W, 10 Pa, 100 standard cubic cm per min), and blue\udlight (400 nm) significantly faster than multilayered spores were. We have thus succeeded in the uniform preparation of reproducible,\udhighly concentrated spore monolayers with the potential to generate BIs for a variety of nonpenetrating surface decontamination\udtechniques.