The relationship between chitin and microorganisms

Chitin is contained in many of the cell walls of filamentous fungi, commonly known as mold. Chitin is also found in the cuticle and digestive system of insects, and this chitin is broken down by chitinase, a chitin-degrading enzyme found in actinomycetes and Bacillus bacteria, and used as food. In other words, there is a constant circulation of abundant chitin in the soil ecosystem, with microorganisms that have chitin and those that do not maintain a balance while competing with each other.

Many of the fungi that contain chitin are pathogenic, and if there is a lack of chitin in the soil, the number of actinomycetes and bacillus bacteria will decrease, making it impossible to suppress pathogenic fungi and resulting in soil with a high incidence of disease. Conversely, in soil that is rich in chitin, beneficial microorganisms such as actinomycetes and bacillus bacteria suppress pathogenic fungi, creating an extremely beneficial environment for plant growth.

●Characteristics and functions of actinomycetes

Since the cell walls of pathogenic bacteria such as Fusarium contain chitin, actinomycetes secrete enzymes such as chitinase and chitosanase to break down the chitin. They also produce many antibacterial substances such as streptomycin to suppress pathogenic bacteria. Actinomycetes also create a symbiotic environment with lactic acid bacteria and photosynthetic bacteria.

*About pathogenic actinomycetes

Most actinomycetes are not pathogenic to plants, but it is known that potato scab and sweet potato root rot are caused by a few pathogenic actinomycetes. However, because these actinomycetes do not secrete chitinase, research has shown that the application of chitin does not increase the proliferation of pathogenic bacteria, and rather the proliferation of beneficial actinomycetes suppresses the activity of pathogenic actinomycetes.