Optimization of Enzyme-assisted Extraction Technology for Tartary Buckwheat Shell Procyanidins with Response Surface Methodology

This study was conducted to investigate the effects of cellulase dosage, enzymolysis time, pH and enzymolysis temperature on procyanidin extraction rate by single factor experiment, with tartary buckwheat shell as an experimental material.Main process parameters were optimized to obtain a regression model by response surface methodology. The results of variance analysis indicated that the regression model reflected the relationship between buckwheat shell procyanidin extraction rate with enzyme dosage, enzymolysis time, pH and enzymolysis temperature; and the optimal process parameters were enzyme dosage of 6.5 mg/g, enzymolysis time of 1.5 h, pH at 4.7 and enzymolysis temperature at 46 ℃. Three parallel experiments were conducted under these process parameters. In practice, the highest procyanidin extraction rate was 6.78 g/100 g. The relative error between the predicted value of regression model and the actual value was 1.3%. The regression equation fitted the real situation better.

The Nutrient Quality of Cassava by Addition of Cow Rumen Fluid Enzyme

The research was conducted to study the effect of crude enzyme from cow rumen fluid on nutrient quality of cassava substrates through hydrolysis method. Completely randomized design （CRD） in this research consisted of 4 materials from cassava with its 11 combinations （the total was 15 treatments） with 3 replications. The fifteen treatments were tuber （T）, leaves （L）, peel （P）, onggok （O）, tuber ＋ leaves （TL）, peel ＋ tuber （PT）, tuber ＋ onggok （TO）, leaves ＋ peel （LP）, peel ＋ onggok （PO）, onggok ＋ leaves （OL）, leaves ＋ tuber ＋ peel （LTP）, leaves ＋ tuber ＋ onggok （LTO）, peel ＋ leaves ＋ onggok （PLO）, peel ＋ tuber ＋ onggok （PTO）, peel ＋ leaves ＋ tuber ＋ onggok （PLTO）. Rumen fluid was centrifuged at 10,000 rpm for 15 minutes in 4 ~C. Supernatant was reacted with ammonium sulphate （60%） and incubated in the freezer at 4 ~C for 24 hours. The ground cassava was added by rumen fluid crude enzyme at the dosage of 1% （b/v）. The cassava substrates were kept for 24 hours in room temperature. The addition of rumen fluid enzyme on cassava did not significantly affect dry matter losses （0.96%-2.08%）, but it significantly decreased crude fiber （8.61%-17.83%）. And On the other hand, it increased total sugar （15.19%-29.52%）. The conclusion of this research was that the addition of rumen fluid enzyme on cassava substrates was able to decrease crude fiber （17.83%） and the best total soluble sugar was in tuber （29.52%）, but for dry matter, it was similar to control in the range of 0.96%-2.08%.

Protection of a cytidine deaminase gene gainst toxicity of high dose chemotherapy in mice

Objective： To explore the feasibility of transfecting cytidine deaminase （CD） gene into mouse bone marrow cells in order to observe the drug resistance of high dose Ara-C and improve the tolerance of myelosuppression following combination chemotherapy. Methods： Human cytidine deaminase gene was transfected into mice bone marrow cells by retroviral vector. Resistant colony-forming unit granulocyte-macrophage （CFU-GM） assay was performed after the transfected mice bone marrow cells treated by the Ara-C. DNA was extracted from mice bone marrow cells. The drug resistant gene in mice bone marrow cells after transfection was detected by PCR. Results： Bone marrow cells of the donor mice cultured with the retroviral producer cells showed the drug resistant colonies and resistance to Ara-C, so did accept mice transplanted with the CD gene （CFU-GM of donor mice was 52%, χ^2 = 124.62, P 〈 0.01; accept mice was 54%, χ^2 = 126.26, P 〈 0.01, both compared with the contrast group）. The animal survival rate was significantly higher in gene transfected group than that of the control （χ^2= 7.42, P 〈 0.01）. CD gene of transfected bone marrow cells was confirmed by PCR. Conclusion： CD gene can be transfected into bone marrow cells of mice efficiently and increase the drug resistance to Ara-C.

A Novel Hydrolytic Product from Flesh of Mactra veneriformis and Its Bioactivities in Calcium Supplement

To prepare calcium-binding peptides, the flesh residue of Mactra Veneriformis was subjected to enzymatic hydrolysis. By comparing the capability of combining calcium of the hydrolyzates, pepsin was confirmed to be the most suitable enzyme for hydrolyzing the flesh residue to release calcium-binding peptides among the seven tested proteases. The pepsin hydrolyzate (PHM) was divided into three fractions according to the molecule weight of its composition, which ranged from 0.5 to 15 kDa. The low-molecule-weight fraction named PHM-3 had the highest capability in combining calcium. The peptides existing in the PHM-3 fraction consisted of higher contents of Glu, Ala and Leu, and could produce one type of calcium-peptide complex by powerfully chelating calcium ions. PHM-3 products could effectively increase calcium absorption and retention while they decreased the calcium excretion in animal tests. Additionally, symptoms caused by low calcium bioavailability in ovariectomized rats, such as bone mineral density reduction and mechanical strength loss could be significantly ameliorated by the hydrolytic products addition in diet.

Application of cellulase in producing reducing sugar with waste lignocellulosic

The cellulase expands the use of waste lignocellulosic and improves the feasibility of ethanol production with waste lignocellulosic. In this paper the types, mechanisms of cellulase and its application in reducing sugar production were presented in detail. The strains that produce cellulase and methods for improving the cellulase activity in reducing sugar production with waste lignocellulosic were described.

Dehydrogenase Activity of Soil Microorganisms and the Total DNA Level in Soil of Different Use

The aim of the study was to find the interrelations between the activity of intracellular dehydrogenases, abundance of microorganisms, and the level of soil DNA in the Mollic Gleysol profile, with notification on the dominant DNA form （extra-or intra-cellular）, depending on the type of land use. Two neighbouring meadows were selected for investigations： one systematically cultivated and fertilized and the other deprived of any effect of anthropogenic activity, used as a control. We have demonstrated that dehydrogenase activity （DHA）, the DNA content and microbial abundance strongly depended on the type of land use. DHA exhibited a significant correlation with the DNA content （r = 0.99^＊＊＊ and r = 0.74^＊, for cultivated and control sites, respectively）. This relationship with such a high r value might suggest domination of the intracellular form of DNA in the cultivated meadow, which is also confirmed by the c.a. 13% increase in microorganism abundance in the cultivated soil. The optimal conditions for microbial activities were defined by the significant positive interrelationships between microbial abundance and the total organic carbon content, and a negative correlation with pH, redox potential and soil bulk density.

秸秆汽爆分级长短纤维酶解性能差异性的研究

降低酶解过程中纤维素酶用量是克服木质纤维素资源炼制过程经济关的关键因素。本研究探索了秸秆汽爆分级后长短纤维酶解性质的差异及其来源,以及利用汽爆分级降低用酶量的可能性。结果表明,分级后的短纤维酶解难度较长纤维显著降低,其酶解率在用酶量仅5 FPU/g DM的情况下即可超过长纤维在20 FPU/g DM时的酶解率,将用酶量降低75%,这主要是由于长短纤维的组织来源不同。由于力学强度的差别,汽爆后秸秆不同组织粒径各异,为分级提供了基础。短纤维主要由来自髓芯的薄壁细胞组成,纤维素结晶度较低,较长纤维具有更低的酶解难度。此外在短纤维酶解过程中束缚水释放更加充分,提高了传质效率,有利于降低产物抑制对酶活性的影响。本研究为提高木质纤维素原料均一性提供了一种有效的方法,对木质纤维素资源的开发具有重要意义。