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 shiitake mushroom during the three-month vegetative phase. Two strains were compared: a normal strain (2105) and a mutant strain (2105 D). The CO₂ concentration in the plastic bag culture of the normal strain increased in a couple of week to over 10% and the O₂ decreased to 2.4% with the normal strain. Changes in the gas atmosphere inside the sawdust cultures of the mutant strain started more slowly. The CO₂ concentration later 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. These 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 activities than the normal strain. Fructose was totally depleted before fruiting in the medium of both strains. Glucose and mannitol decreased in the medium of the normal strain. but not in the medium of the abnormal one. Abnormal fruiting of the mutant strain was considered to be due to differences in carbohydrate metabolism.