CHANGES IN GAS-COMPOSITION AND EXTRACELLULAR ENZYME-ACTIVITY DURING GROWTH OF SHIITAKE (LENTINULA-EDODES) ON SAWDUST

Atmospheric O2 and CO2, extracellular laccase, cellulase and xylanase activities were determined weekly from sawdust cultures of the shiitak e mushroom during the three-month vegetative phase. Two strains were c ompared: a normal strain (2105) and a mutant strain (2105 D). The CO2 concentration in the plastic bag culture of the normal strain increase d in a couple of week to over 10% and the O2 decreased to 2.4% with th e normal strain. Changes in the gas atmosphere inside the sawdust cult ures of the mutant strain started more slowly. The CO2 concentration l ater increased to a higher level than that with the normal strain. All the enzyme activities (laccase. xylanase and cellulase) of the normal strain started at an earlier stage than those of the mutant strain. T hese results indicated that the mutant strain had a longer adaptation phase in the sawdust medium, i.e. it grew more slowly. Laccase was the first enzyme to appear in the medium of both strains. During weeks 4 and 8 the mutant strain showed much higher xylanase and cellulase acti vities than the normal strain. Fructose was totally depleted before fr uiting in the medium of both strains. Glucose and mannitol decreased i n the medium of the normal strain. but not in the medium of the abnorm al one. Abnormal fruiting of the mutant strain was considered to be du e to differences in carbohydrate metabolism.