Why is green mold infection so common in edible mushroom production?

In edible mushroom production, many people see green mold as a cancer, and it is extremely annoying. Saying that green mold is one of the main contamination sources for edible mushrooms, most people would not disagree. There are many routes by which edible mushrooms become contaminated with green mold, such as incomplete sterilization, lax aseptic technique, improper raw material handling, a high background level of contaminating microorganisms in the environment, and many other reasons.

Reasons why Trichoderma infection is common in edible mushroom production:

Edible mushrooms can produce enzyme systems that break down cellulose, hemicellulose, and lignin, among others. The amount of these enzymes and the level of enzyme activity vary depending on the different species and genera of edible mushrooms, the type of substrate, and the physiological development stage they are in.

Cellulose is a macromolecule with a supramolecular structure. Research has shown that the cellulase of basidiomycetes is not a single enzyme but a multi-enzyme system. Among these, two have been studied more clearly, namely C1 enzyme and Cx enzyme.

Most basidiomycetes mainly produce C1 enzyme, and only a few can produce Cx enzyme. The activities of both C1 enzyme and Cx enzyme in Trichoderma are quite high, far stronger than the activity in edible mushroom species. Trichoderma contamination often occurs during the cultivation of edible mushrooms, and one possible reason is that the cellulose-degrading enzyme system of Trichoderma gains the upper hand.

Based on the above analysis of enzymes, simply reducing the nutrients in the edible mushroom culture medium to lower the Trichoderma contamination rate can play a certain role, but it is not advisable, because an unbalanced carbon-to-nitrogen ratio will inevitably affect the yield of edible mushrooms. It is preferable to start with sterilization, aseptic technique, and scientific management.