Cellulase induction by sophorose in washed myceliu...

Cellulase induction by sophorose in washed mycelium

The synthesis of cellulase in washed mycelium was markedly induced by sophorose.In mycelium cultured with sophorose on an induction medium for 24 h，cellulase production of Trichoderma approached a maximum with a lag period of 2—3 h（see Figure 5）.［6］The washed mycelia of different wild strains（1096，Mo3，G109，D-92）and mutants（EA3-867，N2-78，W24，4030，G023，G58）of Trichoderma，and the mutant EA3-867 ofvarious ages（even as young as the short hyphal filaments 15 h old from inoculation）were all able to produce cellulase in which C1 and Cx cellulase were predominantly extracellular，whereas cellobiase was mainly intracellular（see Figure 3）.［6］

The formation of cellulase was affected by the inducer，mineral elements（N，P，Fe2+Mn2+），temperature，pH，aeration and the physiological conditions of the mycelium.［6］The cellulase synthesis stopped soon after the sophorose was removed from the medium.The earlier the sophorose was removed，the less the cellulase was induced.The optimal concentration of sophorose was 10-5—10-3 M.No cellulase was induced in washed mycelium by cellulose（cellulose powder，rice straw cellulose，0.5%）or cellobiose（10-4—10-2 M）.Table 1 presents the nutrient requirements for mycelial growth and cellulase induction.The optimal temperature of induction was 30℃.The range of pH used for induction was 3—6.The production of cellulase was markedly stimulated by O2 and strongly depressed either by the absence of O2 or by inhibitors of respiration such as iodoacetate（IA），sodium fluoride（NaF），malonate，soidum azide（NaN3）or 2，4-dinitrophenol（DNP）（see Figure 6）.These data indicate the involvement of respiration in cellulase production either by the supply ofintermediates or ATP.The induction of cellulase in washed mycelium was also greatly inhibited by inhibitors of nucleic acid synthesis，e.g.actidione，5-fluouracil and 6-azauracil.［6］