Isolation And Identification Of Cellulase Producing Strain From Intestine Of Termites And Optimization Of Its Enzyme - Producing Conditions

Cellulose, the largest quantity synthesized by plant, is a natural and inexhaustible renewable resources. Cellulose is hard to degrade because of chemical composition, molecular structure and the protective layer which formatted by hemicellulose and lignin. Although chemical methods can degrade cellulose, there is environmental pollution. Enzymatic degradation of cellulose fiber will be the research emphasis and the main tendency as it have forte of high performance and environment-friendly.As the major biological groups fed by cellulose, termites have a symbiosis system with microorganisms which can degrade cellulose in its gut. In this experiment, We use isolation medium which hold CMC-Na as the sole carbon source, isolated cellulose degradation 20 strains bacteria and 30 strains fungi from the intestine of Odontotermes formosanus by plate streaking. By observation of morphology、physiological and biochemical tests and identification of molecular biology, the results show that strain HUB-Ⅲ-003 is Bacillus cereus, strain HUB-Ⅲ-621 is Bacillus subtilis, strains HUB-Ⅲ-620 and HUF-Ⅲ-660 are Aureobasidium pullulans. Moreover, Single-factor test analysis, Plackett-Burman design and response surface analysis showed that the best fermentation medium components and conditions for enzyme production of the strain HUB-Ⅲ-620 are NaCl 9g/L、MgSO4 0.41g/L、KH2PO4 0.5g/L、CaCl2 0.77g/L、(NH4)2SO4 1g/L. CMC-Na 21.88g/L. yeast extract 1.0g/L、distilled water 1000ml; inoculum amount 5%(v/v)、liquid volume 50mL/250mL、initial pH 6.0、180r/min、28℃、constant temperature shaking for 5 days, respectively. The enzyme activity of cellulase produced by strains HUB-Ⅲ-620 is (598.00±2.56)×10-3IU/mL, and increased 5% compared to the before optimized. In addition, we studied the enzymatic properties of strain HUF-Ⅲ-620, the result suggested that the best action temperature of strain HUF-Ⅲ-620 is 50℃, the best pH value is 6.0.