Effect of H202 on the Contamination of Pleurotus ostreatus mycelium, by David Klorig
[David was a junior at Mt. Vernon High School in Virginia when this project placed Second in Botany at his school, and then Third in Botany at his regional science fair in early 2000. Following is the abstract he wrote describing the project.]
This experiment involved a method of growing mushrooms which involves the addition of hydrogen peroxide to the substrate on which mushroom mycelium grows. This hydrogen peroxide keeps out competitor molds and other forms of contamination. This problem has traditionally been solved by using lengthy sterilization processes and a completely sterile growing environment. This new method claims to allow the user to forgo this sterilization, and allow an easy and practical way to grow the mushrooms. To test the peroxide method, three different sets of oyster mushroom mycelium were grown on a wheat grain substrate. Two jars grew in the sterile environment of a sterilized and sealed aquarium, in a grow room. Two other jars were grown with hydrogen peroxide added to the substrate. These were placed in the same room as the sterile aquarium, but not inside of the aquarium. Also two jars were grown as a control, in which no steps were made to sterilize it and they were placed in the same room as the other sets of jars. For each jar prior to inoculation, the wheat grain was sterilized in a pressure cooker along with the jars themselves. All 6 jars were inoculated at the same time with equal amounts of spawn, the only difference being the level of sterility that they were to be maintained at and whether or not hydrogen peroxide was added or not.
The growth of the mycelium was observed over the next 3 weeks or so and photographed each time. The jars in the sterile aquarium grew the fastest, but both became contaminated with Blue-Green Mold. The aquarium was not as sterile as was thought. The mycelium eventually out-grew the mold and killed it off itself, however the jars can still be considered contaminated and are not fit for inoculating anything else. The control jars grew the second fastest and then both became contaminated with Black Pin Mold and and unidentified bacterial contaminate. The oyster mushroom mycelium (very hardy) also over ran the molds, but is still unfit for transfer or reinoculation. The hydrogen peroxide containing jars, grew slower, and produced more moisture (probably from the peroxide decomposing into water) and was completely contamination free in both jars."
:idontknow: en tous cas a tester pour avoir le meileur point de vue....
