Images of biological samples undergoing sterilization by a glow discharge at atmospheric pressure

Among the various industrial uses of the glow discharge at atmospheric pressure (GDAP), biological applications such as sterilization are under investigation. In this paper, we present images of a liquid medium (Luria-Bertani broth with tetracycline) contaminated by Escherichia coli bacteria (strain PER 322) undergoing plasma treatment. In most cases, it is found that an exposure time of two to 20 minutes leads to nearly a complete kill of a 10/sup 8//ml E. coli population. The treatment time necessary to obtain a complete kill depends on the plasma power density, the type of gas used, the type of bacteria, and the type of medium.