首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 15 毫秒
1.
The bglS gene encoding endo-1,3-1,4-β-glucanase from Bacillus subtilis was cloned and sequenced in this study. The bglS expression cassette, including PGK1 promoter, bglS gene fused to the signal sequence of the yeast mating pheromone α-factor (MFals), and ADH1 terminator with G418-resistance as the selected marker, was constructed. Then one of the PEP4 allele of Saccharomyces cerevisiae WZ65 strain was replaced by bglS expression cassette using chromosomal integration of polymerase chain reaction (PCR)-mediated homologous recombination, and the bglS gene was expressed simultaneously. The recombinant strain S. cerevisiae (SC-βG) was preliminarily screened by the clearing hydrolysis zone formed after the barley β-glucan was hydrolyzed in the plate and no proteinase A (PrA) activity was measured in fermenting liquor. The results of PCR analysis ofgenome DNA showed that one of the PEP4 allele had been replaced and bglS gene had been inserted into the locus of PEP4 gene in recombinant strains. Different endo-1,3-1,4-β-glucanase assay methods showed that the recombinant strain SC-βG had high endo-1,3-1,4-β-glucanase expression level with the maximum of 69.3 U/(h-ml) after 60 h of incubation. Meanwhile, the Congo Red method was suitable for the determination of endo-1,3-1,4-β-glucanase activity during the actual brewing process. The current research implies that the constructed yeast strain could be utilized to improve the industrial brewing property of beer.  相似文献   

2.
The partition behaviors of β-1,3-1,4-glucanase, α-amylase and neutral proteases from clarified and whole fermentation broths of Bacillus subtilis ZJF-1A5 were investigated. An aqueous two-phase system (polyethylene glycol (PEG)/MgSO4)was examined with regard to the effects of PEG molecular weight (MW) and concentration, MgSO4 concentration, pH and NaCl concentration on enzyme partition and extraction. The MW and concentration of PEG were found to have significant effects on enzyme partition and extraction with low MW PEG showing the greatest benefit in the partition and extraction of β-glucanase with the PEG/MgSO4 system. MgSO4 concentration influenced the partition and extraction of β-glucanase significantly. pH had little effect on β-glucanase or proteases partition but affected α-amylase partition when pH was over 7.0. The addition of NaCl had little effect on the partition behavior of β-glucanase but had very significant effects on the partitioning of α-amylase and on the neutral proteases. The partition behaviors of β-glucanase, α-amylase and proteases in whole broth were also investigated and results were similar to those obtained with clarified fermentation broth. A two-step process for purifying β-glucanase was developed, which achieved β-glucanase recovery of 65.3% and specific activity of 14027 U/mg, 6.6 times improvement over the whole broth.  相似文献   

3.
INTRODUCTION β-1,3-1,4-glucan is the major cell wall compo-nent of barley and other cereal endosperms. It consistsof a polymer of glucose monomers joined by β-1,3-and β-1,4-glycosidic bonds in an irregular fashion(Woodward et al., 1983; Edney et al., 1991). Due toits unique structure, barley β-glucan can be dissolvedin water in high molecular mass and resulting in ahigh viscosity solution. The high-molecular-massβ-glucan released during mashing causes severe fil-tration problems and…  相似文献   

4.
The work is intended to achieve optimum culture conditions of α-galactosidase production by a mutant strain ,Aspergillusfoetidus ZU-GI in solid-state fermentation （SSF）. Certain fermentation parameters involving moisture content, incubation temperature, cultivation period of seed, inoculum volume, initial pH value, layers of pledget, load size of medium and period of cultivation were investigated separately. The optimal cultivating conditions of α-galactosidase production in SSF were 60% initial moisture of medium, 28 ℃ incubation temperature, 18^h cultivation period of seed, 10% inoculum volume, 5.0-6.0 initial pH of medium, 6 layers of pledget and 10 g dry matter loadage. Under the optimized cultivation conditions, the maximum α-galactosidase production was 2037.51 U/g dry matter near the 144th hour of fermentation.  相似文献   

5.
A six-week experiment was conducted to investigate the effects of supplementing different enzyme cocktails in cornsoybean-byproduct diets on broiler chickens＇ growth performance and nutrient utilization. A total of 630 one-day-old Arbor Acre broiler chicks were randomly allocated to 7 experimental groups with 6 replicates of 15 chicks. The group of chicks serving as the control group were fed a basal diet made of mainly corn and soybean meal, mixed with a little fish meal, rapeseed meal and wheat bran. The other six groups were fed the same basal diet supplemented with each a different enzyme complex at the dosage of 0.75 kg enzyme in 1 t basal diet. At the same time, a metabolic trial was carded out on 42 chicks at the 27 d age. The results showed that the average daily mass gain （ADG） of chicks in the starter phase, age 1 d to 21 d, was improved by all enzyme complex supplements except the cocktail made of 230 IU/g α-amylase, 5.6 klU/g β-glucanase, 5.3 kIU/g cellulase, 15.5 kIU/g protease and 37.5 kIU/g xylanase. The enzyme cocktail made of 1.6 klU/g α-amylase, 80 klU/g protease and 1.6 kIU/g xylanase worked out the most significant difference （P〈0.05）. Enzyme supplementation decreased the feed conversion ratio （FCR） by 2.78% to 3.98% （P〉0.05）, indicating better utilization of nutritients. In the grower phase at the age from 22 d to 42 d, the enzyme cocktail made of 4.0 kIU/g β-glucanase, 3.8 kIU/g cellulase, 17.8 kIU/g protease, 4.5 kIU/g xylanase and 44 IU/g α-glactase, and that made of 240 IU/g α-amylase, 1.4.6 kIU/g β-glucanase, 2.0 kIU/g cellulase, 5.7 klU/g protease, 400 IU/g xylanase, 20 IU/g α- glactase and 200 IU/g phytase imporved chicks＇ ADG and FCR significantly （P〈0.05）. These two cocktails also were shown to improve ADG and FCR in the entire period of broiler age from 1 d to 42 d. Exogenous digesting enzymes such as protease and amylase benefited the growth and nutrition utilization in young broilers in the starter phase but barely in the grower phase, indicat  相似文献   

6.
The optimization of cultural conditions for β-glucanase production by Bacillus subtilis ZJF-1A5 was investigated in flask trials. Temperature had gre at effect on β-glucanase production which maximized at optimal temperature of 37 ℃ and decreased significantly when temperature was over 37℃.Charge quantity af fected β-glucanase production significantly. Adding oxygen vector N-dodec ane or acetic ether benefited β-glucanase production, but it depended on the conc entrat ion and charge quantity. The results of fractional factorial design showed that age and size of inoculum and shaking speed were the key factors affecting β -gluc anase production and the cultivation time span to reach the highest β-gluc anase activity. The optimal cultural conditions for β-glucanase production obtai ned wi th CCD were as follows: inoculum age and size (16 h, 3.82%(v/v)), shaking speed 2 10 r/min, charge quantity of 30 mL in 250 mL flask and initial pH 7.0, cultured at 37℃ for 50 h. Repeated experimental results accorded with those predicted b y a second-order polynomial model. The amount of β-glucanase, α-amylase and neut ral protease produced by B subtilis ZJF-1A5 was associated partially with c ell g rowth. Those three enzymes' activities increased following the cell growth and i ncreased significantly when cells entered the stationary phase.  相似文献   

7.
β-glucanase was purified from a solid-state culture of Trichoderma reesei on wheat bran in three steps which comprised ammonium sulfate precipitation, Sephadex G-100 chromatography, and DEAE-Sephadex A-50 chromatography. The molecular mass was determined to be 35.21 kilodaltons by sodium dodecyl sulfate-12.5% polyacrylamide gel electrophoresis. The β-glucanase at low pHs was more stable than that at high pHs, and optimum pH was 5.0. The optimum temperature was 60 ℃, and β-glucanase was relatively stable at below 40 ℃ for 60 min. The Km of the enzyme on β-glucan was 10.86 mg/ml, and the Vmax on β-glucan was 14286 μmol of glucose equivalents per mg of the pure enzyme per min. The β-glucanase activity was significantly inhibited by Fe3+ ions, and was reduced in the presence of Cu2+ ions, Mn2+ ions and Mg2+ ions at 5 mmol/L and 10 mmol/L, respectively. The β-glucanase activity was stimulated by Co2+ ions, Ca2+ ions, Zn2+ ions, and Fe2+ ions at 1 mmol/L and 5 mmol/L, respectively.  相似文献   

8.
An increasing number of monopartite begomoviruses are being identified that a satellite molecule (DNAβ) is required to induce typical symptoms in host plants. DNAβ encodes a single gene (termed βC1) encoded in the complementary-sense. We have produced transgenic Nicotiana benthamiana and N. tabacum plants expressing theβC1 gene of a DNAβ associated with Tomato yellow leaf curl China virus (TYLCCNV), under the control of the Cauliflower mosaic virus 35S promoter. Transgenic plants expressing βC1 showed severe developmental abnormalities in both species. Microscopic analysis of sections of both transgenic and non-transgenic N. tabacum leaves showed abnormal outgrowths of transgenic N. tabacum to be due to disorganized cell division (hyperplasia) of spongy and palisade parenchyma. Immuno-gold labeling of sections with a polyclonal antibody against the βC1 protein showed that the βC1 protein accumulated in the nuclei of cells. The possible biological function of the βC1 protein was discussed.  相似文献   

9.
  相似文献   

10.
Objective:Our objective was to construct a recombinant bacillus Calmette-Guérin vaccine(rBCG) that secretes human interferon-alpha 2b(IFNα-2b) and to study its immunogenicity and in vitro antitumor activity against human bladder cancer cell lines T24 and T5637.Methods:The signal sequence BCG Ag85B and the gene IFNα-2b were amplified from the genome of BCG and human peripheral blood,respectively,by polymerase chain reaction(PCR).The two genes were cloned in Escherichia coli-BCG shuttle-vector pMV261 to obtain a new recombinant plasmid pMV261-Ag85B-IFNα-2b.BCG was transformed with the recombinant plasmid by electroporation and designated rBCG-IFNα-2b.Mononuclear cells were isolated from human peripheral blood(PBMCs) and stimulated with rBCG-IFNα-2b or wild type BCG for 3 d,and then cultured with human bladder cancer cell lines T24 and T5637.Their cytotoxicities were measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT) assay.Results:BCG was successfully transformed with the recombinant plasmid pMV261-Ag85B-IFNα-2b by electroporation and the recombinant BCG(rBCG-IFNα-2b) was capable of synthesizing and secreting cytokine IFNα-2b.PBMC proliferation was enhanced significantly by rBCG-IFNα-2b,and the cytotoxicity of PBMCs stimulated by rBCG-IFNα-2b to T24 and T5627 was significantly stronger in comparison to wild type BCG.Conclusions:A recombinant BCG,secreting human IFNα-2b(rBCG-IFNα-2b),was constructed successfully and was superior to control wild type BCG in inducing immune responses and enhancing cytotoxicity to human bladder cancer cell lines T24 and T5637.This suggests that rBCG-IFNα-2b could be a promising agent for bladder cancer patients in terms of possible reductions in both clinical dosage and side effects of BCG immunotherapy.  相似文献   

11.
Objective: To investigate the immunological function of a yeast expression system for thymosin α1(Tα1). Methods: A constructed Tα1 yeast expression system was used to investigate the immunological function of orally administered Tα1. Dried yeast containing three different concentration of Tα1 was fed to normal Balb/c mice and other Balb/c mice whose immunities were inhibited in advance by cyclophosphamide. Synthesized Tα1 peptide was used as positive control and dried yeast with empty plasmid was used as negative control. CD4 and CD8 levels were detected by flow cytometry assay. TNF-α IFN-γ IL-2, IL-6 and IL-10 levels were detected by liquid chip. Results: In normal Balb/c mice or immune inhibition Balb/c mice, CD8 levels were significantly increased. Especially in immune inhibition Balb/c mice, CD8 levels in synthesized Tα1 group (18.77％±4.72％),small dose group (13.48％±6.17％) and large dose group (22.74％±1.09％) were significantly higher than that in empty yeast control group (7.49％±2.14％). Conclusion: Orally administered Tα1 has its certain immunomodulatory function.  相似文献   

12.
Objective: To construct a eukaryotic expression plasmid pcDNA3.1 (-)-Humanin. Methods: The recombinant plasmid pGEMEX-1-Humanin was digested with restriction endonucleases BamH I and Hind III and the Humanin gene fragments, about 100 bp length, were obtained. Then the Humanin gene fragments were inserted into eukaryotic expression vector pcDNA3.1 (-) and the recombinant plasmids pcDNA3, l(-)-Humanin were identified by sequencing. Results: Recombinant plasmid DNA successfully produced a band which had the same size as that of the Humanin positive control. The sequence of recombinant plasmids accorded with the Humnain gene sequence. Conclusions: A eukaryotic expression plasmid of Humanin was successfully constructed.  相似文献   

13.
The energy of interaction between complementary nucleotides in promoter sequences of E. coli was calculated and visualized. The graphic method for presentation of energy properties of promoter sequences was elaborated on. Data obtained indicated that energy distribution through the length of promoter sequence results in picture with minima at -35, -8 and ＋7 regions corresponding to areas with elevated AT （adenine-thymine） content. The most important difference from the random sequences area is related to -8. Four promoter groups and their energy properties were revealed. The promoters with minimal and maximal energy of interaction between complementary nucleotides have low strengths, the strongest promoters correspond to promoter clusters characterized by intermediate energy values.  相似文献   

14.
1-（2-chlorophenyl） ethanol （CPE） is of health and environmental concern due to its toxicity and its use as an intermediate in pharmaceutical manufacturing. The current work deals with the catalytic reductive dechlorination and detoxification of CPE by Pd/Fe bimetal. CPE was effectively dechlorinated to l-phenyl ethanol （PE） accompanied by the equivalent release of chloride. The extent of CPE dechlorination increased with temperature, Fe dosage and Pd loading. A decrease in solution pH increased CPE dechlorination, resulting presumably from an increase in hydrogen production. Under the specific conditions of 20 g/L Pd/Fe, 0.10% Pd （w/w） and initial pH 5-6, the CPE dechlorination was completed within 145 rain. The dechlorination followed a pseudo-first-order kinetics with an activation energy of 56.7 kJ/mol. The results of toxicity testing showed that CPE was very toxic to Chlorella, whereas PE showed little toxicity. The toxicity of the reaction solution declined gradually and the promoting effects on Chlorella intensified consequently with the dechlorination process. Thus, the reductive dechlorination of CPE to PE by Pd/Fe was a detoxification process. It may be used to effectively reduce the toxicological effects of CPE-contaminated wastewater, thereby enhancing the performance of subsequent biological processes in wastewater treatment.  相似文献   

15.
An increasing number ofmonopartite begomoviruses are being identified that a satellite molecule (DNAβ) is required to induce typical symptoms in host plants. DNAβ encodes a single gene (termed βCl) encoded in the complementary-sense. We have produced transgenic Nieotiana benthamiana and N. tabaeum plants expressing the βC1 gene of a DNAβ associated with Tomato yellow leaf curl China virus (TYLCCNV), under the control of the Cauliflower mosaic virus 35S promoter. Transgenic plants expressing 13C1 showed severe developmental abnormalities in both species. Microscopic analysis of sections of both transgenic and non-transgenic N. tabaeum leaves showed abnormal outgrowths of transgenic N. tabaeum to be due to disorganizedcell division (hyperplasia) of spongy and palisade parenchyma. Immuno-gold labeling of sections with a polyclonal antibody against the βC1 protein showed that the 13C 1 protein accumulated in the nuclei of cells. The possible biological function of the βC1 1protein was discussed.  相似文献   

16.
Carotenoid isomerase(CRTISO)is a key enzyme that catalyzes the conversion of cis-lycopene to alltrans lycopene. In this study, we isolated and characterized the CRTISO gene from Lycium chinense(Lc CRTISO) for the first time. The open reading frame of Lc CRTISO was 1 815 bp encoding a protein of 604 amino acids with a molecular mass of 66.24 k Da. Amino acid sequence analysis revealed that the Lc CRTISO had a high level of similarity to other CRTISO. Phylogenetic analysis displayed that Lc CRTISO kept a closer relationship with the CRTISO of plants than with those of other species. Semi-quantitative PCR analysis indicated that Lc CRTISO gene was expressed in all tissues tested with the highest expression in maturing fruits. The overexpression of Lc CRTISO gene in transgenic tobacco resulted in an increase of total carotenoids in the leaves with β-carotene and lutein being the predominants. The results obtained here clearly suggested that the Lc CRTISO gene was a promising candidate for carotenoid production.  相似文献   

17.
A sequential anode-cathode double-chamber microbial fuel cell (MFC), in which the effluent of anode chamber was used as a continuous feed for an aerated cathode chamber, was constructed in this experiment to investigate the performance of brewery wastewater treatment in conjugation with electricity generation. Carbon fiber was used as anode and plain carbon felt with biofilm as cathode. When hydraulic retention time (HRT) was 14.7 h, a relatively high chemical oxygen demand (COD) removal efficiency of 91.7%–95.7% was achieved under long-term stable operation. The MFC displayed an open circuit voltage of 0.434 V and a maximum power density of 830 mW/m3 at an external resistance of 300 ?. To estimate the electrochemical performance of the MFC, electrochemical measurements were carried out and showed that polarization resistance of anode was the major limiting factor in the MFC. Since a high COD removal efficiency was achieved, we conclude that the sequential anode-cathode MFC constructed with bio-cathode in this experiment could provide a new approach for brewery wastewater treatment.  相似文献   

18.
  相似文献   

19.
The symplectic approach proposed and developed by Zhong et al. in 1990s for elasticity problems is a rational analytical method, in which ample experience is not needed as in the conventional semi-inverse method. In the symplectic space, elasticity problems can be solved using the method of separation of variables along with the eigenfunction expansion technique, as in traditional Fourier analysis. The eigensolutions include those corresponding to zero and nonzero eigenvalues, The latter group can be further divided into α- and β-sets. This paper reformulates the form of β-set eigensolutions to achieve the stability of numerical calculation, which is very important to obtain accurate results within the symplectic frame. An example is finally given and numerical results are compared and discussed.  相似文献   

20.
  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号