Studies On The Method Of Efficient Enzymatic Hydrolysis Of Corn Cob Residue

Biomass, most of which is composed of lignocelluloses, can reach200billion tons every year on earth. Corn cob residue is a kind of high quality lignocellulose resources, which is always wasted and pollutes environment. Corn cob residue is composed of58.6%cellulose,8.07%hemicellulose and17.36%lignin. Because of this, corn cob residue could be used to produce fermentable sugar by cellulase hydrolysis, which lay the foundation of subsequent industrial production, such as lactic acid, ethanol, biofuels etc.The strain named C01selected through corn cob residue as the main carbon source possesses high cellulose enzyme activity, which belongs to Trichoderma by the preliminary identification. Based on the previous experiments, Trichoderma Cl was optimized for its fermentation culture medium. The optimized medium is: KH2PO40.2%, NaC10.01%, MgSO40.03%, NaNO30.2%, FeCl30.001%, CaCl20.01%, Crn starch2%, peptone0.5%, corn cob residue3%, bran1.5%, corn cob0.5%. In250mL conical flask shaking fermentation, the optimized cultivating conditions include:the loading volume40mL, seed age24h, inoculums volume10%, cultivating66hours at28叁at180r/min, under which the enzyme activity for corn cob residue could reach54.5U/mL.Protectants of enzyme were studied in this experiment. The results showed that, tetracycline, sodium azide, sodium thiosulfate had promoting effect on enzyme activity. Tetracycline belongs to antibiotics, sodium azide has antiseptic effect, all of which could inhibit of bacterial growth, and sodium thiosulfate can prevent the oxidation of the enzyme protein. So mixing these three different protectants would be more conducive for the enzyme liquid preservation. The experiment result showed that the optimal formula was0.003%for tetracycline,0.03%for sodium azide,0.02%for sodium hyposulfite. In the process of enzymatic hydrolysis, surfactant Tween-80and polyethylene glycol (PEG) were proofed having promoting effect on enzymatic hydrolysis of lignocelluloses, and the glucose yield had88.9%increasing in case of PEG However, metal ions had no obvious promoting effect on enzymatic hydrolysis. Using four kinds of enzyme liquid from fungi, including Trichoderma C01, Trichoderma27, Trichoderma B08and Aspergillus Niger03, the enzyme activity of corn cob residue, CMC activity, β-glycosidase activity, xylanase activity, pectinase activity and ferulic acid esterase activity were measured. The results showed that xylanase had obvious promoting effect on enzymatic hydrolysis, which was one of the restriction enzyme in enzymatic hydrolysis of lignocelluloses. Pectinase also had promoting effect in enzymatic hydrolysis of lignocelluloses. The results showed that the process of enzymatic hydrolysis of corn cob residue was a synergy of enzymes. Obviously, the results would be helpful for future strain breeding and enzyme making.