Jian Wu

Efficient hydrolysis of corncob residue through cellulolytic enzymes from Trichoderma strain G26 and l-lactic acid preparation with the hydrolysate

To prepare fermentable hydrolysate from corncob residue (CCR), Trichoderma strain G26 was cultured on medium containing CCR for production of cellulolytic enzymes through solid-state fermentation (SSF), resulting in 71.3 IU/g (FPA), 136.2 IU/g (CMCase), 85.1 IU/g (β-glucosidase) and 11,344 IU/g (xylanase), respectively. Through a three-stage saccharification strategy, CCR was hydrolyzed by the enzymatic solution (6.5 FPU/ml) into fermentable hydrolysate containing 60.1g/l glucose (81.2% cellulose was converted at solid loading of 12.5%), 21.4% higher than that by the one-stage method. And then the hydrolysate was used to produce L-lactic acid by a previous screened strain Bacillus coagulans ZX25 in the submerged fermentation. 52.0 g/l L-lactic acid was obtained after fermentation for 44 h, with 86.5% glucose being converted to L-lactic acid. The results indicate that the strains and the hydrolysis strategy are promising for commercial production of L-lactic acid from CCR and other biomass.

Studies on the cellulase production using corncob residue from xylose manufacture by trichoderma sp.B-8 and the characterization of the cellulase

To improve enzymatic hydrolytic efficiency and reduce production cost, the cellulase production by Trichoderma sp. B-8, isolated from corncob residue from xylose manufacture, was investigated, using corncob reside as main carbon source. The optimal carbon and nitrogen sources used in the fermentation medium were as follows: corncob residues 2.5%, wheat bran 0.75%, peptone 0.5% and corn steep liquor 2.0%. The optimal hydrolysis temperature and pH of the cellulase were 45°C and 5.0, respectively. The activities of FPAase and CMCase of the crude cellulase liquor determined at the optimal hydrolysis temperature and pH reached 3.32IU/ml and 25.7IU/ml, respectively. In addition, the most important, the glucose production by saccharifying corncob residue using crude cellulase was as high as 41.0g/L on the 10% (W/V) corncob residues base.

A Mercury Free Method for the Determination of Chemical Oxygen Demand of the Sample with High Salinity and Organic Macromolecule

An improved method for the determination of chemical oxygen demand (COD) is presented. This method is based on the standard method but using silver sulfate as a masking agent for the chloride and using the microwave for the digestion. The method gives tiny errors when the chloride of the samples increases from 606.6 mg/L to more than 30,000 mg/L. The method applies to the samples containing macromolecules and give better results when the sample is prehydrolysed.

Cellulase Production by Submerged Fermentation Using Biological Materials of Corncob Residue with Aspergillus Niger FC-1

In order to improve the cellulase-producing ability, the culture medium components and condition were optimized. The results showed that the cellulase activity in the fermentation broth remarkably increased by using 1% corncob residue combined with 1% wheat bran and 1% corncob as carbon source, taking 0.75% soybean meal and 0.3% KON3 as nitrogen source, and adding 0.3% CaCO3 to stabilize the pH to 5.0. The FPase activity in supernatant of A. niger FC-1 fermented with 50mL of the optimal medium in 250mL shake flasks at 30°C reached 101.6U/mL, which was 4.7 times of that before optimization.

Dynamics of Biogas Fermentation for Industrial Waste and Hydrolysate of Corn Stover

In order to fully utilize industrial waste and corn stover, the experiments were conducted using gulonic acid waste liquor and hydrolysate of corn stover as the methane fermentation raw materials. Real time CH4 and CO2 monitors were used to analyze the anaerobic digestion process. Different temperatures, nutrition and the rates of raw material supply were adopted to investigate the optimal methane fermentation condition. Experiment results showed that both gulonic acid waste liquor and hydrolysate of corn stover were easy to produce methane with as high as 800mL biogas per gram COD biogas yield and 77% methane content under an optimum condition. The potential inhibitor, Sulfate, in the hydrolysate corn stover showed no obvious inhibition at 0.3% level. The investigation also showed that high level of substrate would cause acid production and pH diminishing and finally result in CO2 increase and CH4 decrease. These phenomena indicate that methane production bacteria are the weak portion of the anaerobic digestion system.

Hydrolysis of Corncob Residue by Enzymes from Fungi C1067 and the Products Analysis by Capillary Electrophoresis

To achieve high enzymatic hydrolytic efficiency of corncob residue, one strain, Trichoderma C1067, with the enzyme activity of corncob residue as high as 4.5g/L glucose liberated per hour in 0.5mL crude cellulase and 0.5mL citric acid /sodium citrate buffer under the assay conditions, was carefully studied. The optimal carbon and nitrogen sources used in the fermentation medium are as follows: corncob residues 2.0%, wheat bran 1.5%, corncob 0.5%, rice straw 0.5%, peptone 0.1% and corn steep liquor 4%. The optimal conditions of saccharification for corncob are 55°C and pH 4.0. The sugars gained in the hydrolysate consist of glucose 4.1% and xylose 0.4% after enzymolysis for 72h, tested by capillary electrophoresis.

Study on Dilute Sulfuric Acid Hydrolysis of Corn Stover

The object of this research is to investigate the factors influencing the hydrolysis of corn stover by dilute sulfuric acid and the types of sugars existed in hydrolysate. Experiment results showed that the optimal conditions were hydrolysis temperature 120°C, stover size 20-40 mesh, soak time 36h, reaction time 100 min, H2SO4 concentration 1.5% and solid-liquid ratio 1:8. Sugars gained in the hydrolysate were xylose 3.0%, glucose 0.71%, mannose 0.12% and galactose 0.32% determined by capillary electrophoresis.