Investigating the Effect of Tissue Size on Mycelial Growth of Seven Mushroom Species by Using a Novel Device for Precise Tissue Isolation.

Tissue isolation from mushrooms is frequently practiced by both researchers and growers to isolate new and improved strains. In the present study, we designed a simple and convenient device for precise tissue isolation and therefore investigated the effect of tissue size on mycelial growth of seven mushroom species. The developed device consists of a cutting needle and a transfer needle. The cutting needle was used to obtain circular tissue plugs having a height up to 3 mm and variable diameters (2-5 mm) from mushroom fruit bodies. The transfer needle was a stainless steel round rod (1.5 mm in diameter) with a blade-like end. It can be used for collecting mushroom tissue when the cutting needle fails to extract it. With the aid of these devices, precise tissue isolation was achieved. Plate cultures demonstrated that tissue size had little effect on mycelium extension for Lentinula edodes (the winter shiitake), Hypsizygus marmoreus, and Agrocybe aegerita, but influenced the aerobic mycelium density. For Pleurotus ostreatus, Pleurotus eryngii, and Volvariella volvacea, large tissue plugs produced faster mycelial growth and higher aerobic mycelium density compared with small ones. On the contrary, small plugs from the tissue of the flower shiitake and Agaricus bisporus favored mycelial growth. The present study revealed that the preferable tissue size for mycelial growth varies among mushroom species, and the developed device is expected to greatly facilitate the isolation of new and improved mushroom strains.