Abstract
In recent years, research on improving Auricularia polytricha production in Japan has been indispensable for stabilizing its production base for the future. There are many descriptions of adding calcium carbonate in cultivation instructions and reports of cultivation tests of A. polytricha. However, to our knowledge, there are no reports on the effect of the addition on A. polytricha. We have clarified the effect of adding shell fossils, which have calcium carbonate as the main component and are widely distributed in Japan, on hyphal elongation. Further, yields in cultivation tests suggest that the addition of shell fossils can shorten the incubation period from the typical 60 days or more to 40 － 50 days.
