EFFECTS OF SUPRAOPTIMAL TEMPERATURES ON MERULIUS LACRYMANS

The growth rate of Merulius lacrymans (Jacq.) Fr. decreases very rapidly at temperatures above optimun (about 22[degree]C). No growth occurred above 28[degree]C. The thermal death-time of the fungus at different temperatures above maximum was determined. At 37.5[degree]C the thermal death-time is 4 hours. At this temperature, the respiration is not directly affected, since an appreciable respiration occurred even after 6 hours. On the basis of 14c-experiments and analysis of UV-absorbing material excreted from the mycelium at supraoptimal temperatures, it is suggested that the detrimental effects of supraoptimal temperatures on this fungus include a degradation of the nucleic acids and a subsequent leakage of the nucleotides out of the cells.