Cellulase Production By Microbial Fermentation

Cellulase is one kind of important enzyme product with high xylanase activity, which is mainly composed of endoglucanase, exo-glucanase andβ-Glucosidase. The synergistic effect of these three enzymes can degrade cellulose, which has strong chemical and biological resistance, into simple glucose molecules, having significant meaning to solve some important problems in the world such as energy crisis, food crisis, environmental pollution, and so on. The composition of cellulase is imbalance and the capability of producing cellulase is low, which is the main reason for limited application of cellulase. But it did not make a breakthrought at all time.In this study, Trichoderma reesei YZ-68 was used as objects. this study included mutation breeding, optimiaing the culture of cellulase production and optimizing the condition of cellulase production.UV, MW, NaNO2, NTG mutagenesis was used to obtain a mutant strain of Trichoderma reesei which could produce high yield of cellulase. The culture condition of NTG-84 in flask was investigated, then the optimal fermention medium and conditions were confirmed. The content of carbon source, nitrogen source and hinitial pH which had important effects on cellulase production were studied especially. The optimal medium were got as: bran 2%, microcrystalline cellulose 8%, Tryptone 3%, MgSO₄·7H₂O 0.15%, KH₂PO₄·3H₂O 2% , (NH₄)₂ SO₄ 0.2%, Tween-80 1 mL/L and initial pH value 5.5. With the volume of liquid 80 mL/500 mL, inoculum size 2%, culture time 120 h, culture temperature 30℃.The pilot-scale fermentation was carried in 10 L fermenter. Pack fluid amount to 6.5 L, the aeration rate is 1.5 vvm and the initial agitation speed was 200 r/min, after 24 h the agitation speed and aeration rate should be adjusted according to the dissolved oxygen which should be over 20%. At the same time, the carbon source microcrystalline cellulose adopt stream plus methods for adding, after 120 h's fermentation, the yield of FPA is 72.98 IU/mL.