SELECTIVE SYNTHESIS OF XYLANASES FOR PULP BIOBLEACHING BY TRICHODERMA REESEI RUT C-30

Effects of carbon resource,culture temperature,initial pH value and carbon-to-nitrogen ratio on xylanase and cellulase synthesis by Trichoderma reesei Rut C-30 have been investigated.The results show that the mixture of corncob xylan and sulfite pulp as carbon resource could stimulate the synthesis of xylanase and cellulase;The culture temperature of 25-26 ℃ could stimulate the synthesis of xylanase and cellulase,the highest xylanases activity((156.53 IU/mL)) and CMCase activity(0.589 IU/mL) could be obtained after 96 h cultivation;When culture temperature was 35-36 ℃,the highest xylanase activity(113.73 IU/mL) and CMCase activity(0.208 IU/mL) could be obtained after 48 h cultivation;Low initial pH value could stimulate the synthesis of cellulase,whereas high initial pH value could prolong culture time of xylanase synthesis and depress the synthesis of cellulase.When the initial pH (values) were 4.0,4.4,4.8,5.4,6.0,the ratios of xylanase to cellulase were 259,327,425,865,1 016,respectively,(after) (72 h) cultivation;Low ratio of carbon to nitrogen could stimulate the synthesis of cellulase,and high ratio of carbon to nitrogen could not only retard the synthesis of xylanase,but also depress the synthesis of cellulase.In the controlled cultivation of T.reesei Rut C-30 with a mixture of 6.5 g/L corncob xylan and 0.5 g/L sulfite pulp as carbon source,high xylanase activity(186.93 IU/mL) and low CMCase activity(0.156 IU/mL) could be obtained after 6 days (cultivation).At the earlier stage,temperature was controlled to 35-36 ℃ with an initial pH value of 6.0 and higher (ratio) of carbon to nitrogen(7.2),while at the later stage temperature was reduced to 25-26 ℃.