黑曲霉WB-1固态发酵产单宁酶的研究

对黑曲霉WB-1固态发酵产单宁酶进行了研究。考察了发酵温度、发酵时间、外加碳源对黑曲霉WB-1产单宁酶的影响,同时考察了单宁酶的储存稳定性以及最适反应温度、pH值。结果表明,黑曲霉WB-1产单宁酶的最佳发酵温度和发酵时间分别为28℃和96h,外加碳源有利于单宁酶的产生,且以甘油为外加碳源时效果最好。所产单宁酶的最适反应温度和pH值分别为30℃和6,且具有一定的低温(4℃)储存稳定性。     

过氧化氢-乙酸联合预处理对甘蔗渣酶解和发酵的影响

采用过氧化氢-乙酸(HPAC)对甘蔗渣(SCB)进行了联合预处理。以预处理后的甘蔗渣为原料,先进行酶水解,然后将水解液进行乙醇发酵,探讨预处理对甘蔗渣酶解和发酵的影响。实验结果表明：20 g甘蔗渣,加入150 mL过氧化氢水溶液(75 mL过氧化氢(30%)和75 mL水)和150 mL乙酸(99%),硫酸用量为过氧化氢-乙酸溶液体积的0.5%,在70℃反应2 h时,HPAC预处理脱除了88.85%的木质素,并使90.10%的纤维素保留在底物中。底物(HPAC/70-SCB-0.5)的酶可及度是80.30 mg/g,与相同条件下单独过氧化氢预处理(HP/70-SCB)和单独乙酸预处理(AC/70-SCB)相比,分别增加了38.26%和31.08%,甘蔗渣木质素的表面覆盖率从原料的0.66降低至0.22。酶解上清液在酶用量为5 FPIU/g(以底物计)条件下水解后,葡萄糖得率是87.63%,分别是HP/70-SCB和AC/70-SCB的6.89和20.62倍,发酵产乙醇质量浓度是7.57 g/L,分别是HP/70-SCB和AC/70-SCB的7.65和22.94倍。     

幽门螺杆菌过氧化氢酶基因克隆及表达

目的 克隆幽门螺杆菌(Helicobacter pylori,HP)过氧化氢酶(katA)基因并在大肠杆菌中进行表达。方法 采用PCR扩增幽门螺杆菌katA全长基因,将其克隆入pET-11c载体中,经测序证实后,在大肠杆菌中进行表达,产物用Western blot检测其抗原性并进行N末端氨基酸的测序。结果 幽门螺杆菌katA基因全长1 518bp,编码氨基酸505个。在BL21(DE3)中的表达量约占细菌总蛋白的24.9％,表达产物经SDS-PAGE显示其相对分子质量与软件预测结果 58 000相符,N末端5个氨基酸测序结果与Hp中天然的katA完全一致,经Western blot检测可被 Hp全菌抗血清识别。结论 katA能在大肠杆菌中进行高效表达,具有良好的免疫反应性,可望为研究 Hp的致病机理、实验诊断及亚单位疫苗等提供充足的katA原材料。     

黑曲霉产β-葡萄糖苷酶发酵条件的研究

通过单因素及正交实验对现存黑曲霉菌株产酶发酵条件进行了研究,结果表明:当培养基为:玉米芯4.0%;酵母粉1.0%;KH2PO40.4%;MgSO40.08%;(NH4)2SO40.4%;培养温度30℃,摇床转速220r/min,接种量6.0%,装液量40mL/250mL,初始pH值5.0,发酵周期168h;此条件下β-葡萄糖苷酶酶活达56.96IU/mL。     

聚乙烯醇降解酶发酵过程模拟

应用Matlab软件对聚乙烯醇降解酶发酵过程数学模型进行最优参数估计和非线性曲线拟合,得到了假单胞菌Pseudomonas sp XT11-Z90S发酵生产聚乙烯醇(PVA)降解酶的菌体生长、底物PVA消耗和聚乙烯醇降解酶合成的数学模型.结果表明,模型计算值和实验结果非常接近,其平均相对误差绝大部分小于10％,说明所建数学模型能较好地对聚乙烯醇降解酶发酵过程进行模拟.     

黑毛茶中产单宁酶真菌的筛选及产酶条件研究

采用富含单宁酸的平板培养基对黑毛茶中产单宁酶的真菌进行筛选,经纯化后初步鉴定该菌为黑曲霉,并对其中一株黑曲霉WC-2产单宁酶的发酵条件以及发酵培养基的组成进行了优化。优化后的条件为:五倍子渣含量80%,外加碳源为α-乳糖、添加量1%,外加氮源为硝酸铵、添加量0.5%,发酵温度37℃,发酵时间72h。在此条件下,单宁酶活力最高达到27.06U·g-1。     

超声波对牛肝过氧化氢酶催化活性影响的机理研究

牛肝过氧化氢酶（CAT）经超声波处理后,酶活性比未经超声波处理的酶液活力有所下降。经超声波处理后的CAT,其动力学参数Km值变大、Vmax值基本不变;紫外最大吸收波长和荧光发射峰基本没有变化,吸收值稍有差异,出现了差示吸收峰,荧光强度发生改变。     

锰过氧化氢模拟酶合成及应用研究进展

介绍了锰过氧化氢模拟酶的常见模型化合物结构与催化特点。水杨醛希夫碱模型化合物合成方法简单,大环配合物结构稳定,能形成多核结构,催化活性高。目前大多数锰酶模拟物均采用这两类结构。锰过氧化氢模拟酶在烯烃环氧化、酚类降解、DNA切割、清除DPPH自由基等方面均有广泛应用。合成结构与功能更加接近天然酶的多核模型化合物将成为该领域的主要研究方向,有助于人们开发Mn CAT模拟酶的应用。     

锰过氧化氢模拟酶合成及应用研究进展

介绍了锰过氧化氢模拟酶的常见模型化合物结构与催化特点。水杨醛希夫碱模型化合物合成方法简单,大环配合物结构稳定,能形成多核结构,催化活性高。目前大多数锰酶模拟物均采用这两类结构。锰过氧化氢模拟酶在烯烃环氧化、酚类降解、DNA切割、清除DPPH自由基等方面均有广泛应用。合成结构与功能更加接近天然酶的多核模型化合物将成为该领域的主要研究方向,有助于人们开发Mn CAT模拟酶的应用。     

Bubble column fermentation of olive mill wastewaters by Aspergillus niger

A bubble column (tower) fermenter was used to study the growth of Aspergillus niger on olive mill wastewaters (OMW). The gas hold-up, mixing time and oxygen transfer coefficient values were studied in terms of superficial air velocity. These characteristics were clearly affected by OMW. The growth of A. niger resulted in a filamentous suspension with no pellet formation and the specific growth rate was 0–2 h^?1. The growth rate was limited by the oxygen transfer rate at 90 mmol dm^?3 h^?1 when pO₂ was lower than 2%.     

Permeabilization of Aspergillus niger by Reverse Micellar Solutions and Simultaneous Purification of Catalase

Abstract

Reverse micellar solutions(RMS) of sodium bis‐ (2‐ethylhexyl)‐sulfosuccinate (AOT) in aliphatic organic solvents were used for permeabilization and protein removal directly from Aspergillus niger cells. Most of the cell wall proteins (～95–100%) were solubilized into the reverse micelles solutions. A significant fraction of intracellular catalase (26–30%) permeates out of the cells and remains on the cell surface and is recovered in a cell wash. Because of it's size the catalase in not solubilized in the RM water pools and thus is not detected in the stripping solution used to recover other proteins from the organic reverse micellar solutions. The remaining amount of catalase is recovered by breaking the cells in purer form. Multiple extractions were used for the extraction of the cell wall proteins followed by ultrasonication of the cells to recover intracellular catalase in a purified form. Therefore, catalase with 5 fold purification was recovered in 88% yield from the RMS‐ treated cells.     

ETHANOL FERMENTATION OF MIXED GLUCOSE AND XYLOSE BY PICHIA STIPITIS

Pichia stipitis CBS 5773 yeast cells were used to ferment the mixed substrates consisted of glucose andxylose to produce ethanol.The effects of aeration rate,initial substrate concentration and pH on substrateutilization and ethanol yield were evaluated.During batch fermentation,the oscillation phenomena in cell growthwere observed at low aeration rate,whereas the diauxic growth at high aeration rate.The substrate utilizationratio and ethanol yield reached 95％ and 0.46g/g respectively under appropriate operation conditions.Amodified unstructural model was proposed to simulate the diauxic cell growth,substrate consumption andproduct formation.     

超临界水中葡萄糖气化制氢的热力学分析

引　言氢气是一种高效清洁的二次能源 ,具有无污染、可储存、可运输的特点 ,被公认为未来最有希望的能源载体 .在超临界水中进行生物质的气化制氢 ,气体产物中H2 的摩尔分数甚至可超过 5 0 % ,反应不生成焦油、木炭等副产品 ,不会造成二次污染 ,对于含水量高的湿生物质 ,不需要     

菌丝球形态的黑曲霉发酵液浸出铜尾砂

尾砂中含有大量的金属,是一种潜在的可利用资源。旨在研发一种从铜尾砂中回收铜的生物浸出方法。利用正交设计,通过摇瓶试验,研究培养温度、发酵时间、接种量及培养基成分对黑曲霉菌丝球形态的影响,进而研究不同菌丝球形态的黑曲霉发酵液对尾砂中铜的浸出。研究表明,铜的浸出率随着黑曲霉菌丝球直径的减小而升高。在温度30℃,接种量0.8%(OD₆₀₀=0.1),马铃薯-蔗糖含量30%,发酵时间65 h的优化发酵条件下,获得大量表面光滑、直径为0.96 mm的菌丝球;利用该条件下的发酵液,在30℃,180 r·min^-1条件下浸出3 d,铜的浸出率达83.25%。     

Hg(II) Removal from Aqueous Solution by Dead Fungal Biomass of Marine Aspergillus niger: Kinetic Studies

Abstract

Mercury removal from wastewater is a recognized pollution control challenge today. In the present investigation, the biosorption of Hg(II) onto the dead biomass of four different species of marine Aspergillus, prepared by alkaline treatment, was studied. Among the cultures studied, A. niger was found to be the most efficient for Hg(II) removal. The effects of initial Hg(II) concentration, contact time, pH, temperature, and biosorbent dosage on biosorption were also investigated. It was observed that biosorption equilibriums were established in about 2 h. Under the optimum conditions (pH: 3.0, Hg(II) concentration: 250 mg/L, biomass dose: 0.8 g/L, temperature: 40°C and contact time: 2 h), 40.53 mg Hg(II) was biosorbed per gram of dead biomass of A. niger. Kinetic studies based on fractional power, zero order, first order, pseudo first order, Elovich, second order, and second order rate expressions have also been carried out where the pseudo second order model exhibited best fit to experimental data. The intra‐particle diffusion study revealed that film diffusion is the rate‐limiting sorption process for Hg(II) on A. niger. The nature of the possible cell–metal ion interactions was evaluated by FTIR, SEM, and EDAX analysis. These examinations indicated the involvement of ‐OH and ‐NH₂ ⁺ groups in the biosorption process present on the surface of the dead fungal biomass. Here, Hg(II) ions were deposited on the surface of the biomass as a film like structure.     

Modulated gluconic acid production from immobilized cells of Aspergillus niger ORS‐4.410 utilizing grape must

BACKGROUND: Gluconic acid (GA) production by immobilized cells of mutant Aspergillus niger ORS‐4.410 on polyurethane sponge (PUS) and calcium‐alginate (Ca‐alginate) was evaluated in repeated batches of solid state surface fermentation (SSF) and submerged fermentation (SmF) conditions, respectively, utilizing rectified grape must as carbon source. RESULTS: The passive immobilization of cells in fermentation medium solid support of having 0.4 cm³ cube size, 4% spore suspension, 0.6 g inoculum of PUS immobilized cells at 32 °C and 2.0 L min^?1 resulted in the maximum GA production (88.16 g L^?1) with a 92.8% yield, while the Ca‐alginate matrix with a 0.5 cm diameter bead size, 2–3% spore suspension, 15 g inoculum at 34 °C and 150 rpm agitation speed revealed 67.19 g L^?1 GA with a 85.2% yield. Repeated use of PUS showed higher levels of GA (110.94 g L^?1) in the third–fourth fermentation cycles with 95–98% yield and 22.50 g L^?1 d^?1 productivity under SSF that was 2.5‐fold higher than the productivity obtained from a typical fermentation cycle, and 54% greater than the productivity obtained with repetitive use of Ca‐alginate immobilized cells of A. niger under SmF. CONCLUSION: Using immobilized cells of A. niger in PUS, the rectified form of grape must can be utilized for GA production as an alternative source of carbohydrate by replacing the conventional fermentation conditions. Copyright © 2008 Society of Chemical Industry     

超临界水氧化法降解葡萄糖的研究

实验研究了葡萄糖在超临界水中的氧化降解。结果表明 ,超临界水氧化技术能有效地降解废水中的葡萄糖 ,COD去除率可达 98%。随着反应温度的升高、压力的增大、停留时间的延长和初始废水浓度的增大 ,COD去除率也随之提高。葡萄糖在超临界水中氧化降解的动力学方程为- d[COD]dτ =2 4.2 exp - 3.0× 10 4RT [COD]1.0 3 [O2 ]0 .0 670     

Production of β-glucosidase by Aspergillus niger using carbon sources derived from agricultural wastes

The effects of various medium carbon sources and salt solutions on the production of β-glucosidase (βG, EC 3.2.1.21) by Aspergillus niger have been studied. β-Glucosidase productivity was found to be 50 times greater than that reported previously.¹ This higher productivity was achieved by employing a mutant strain of the organism, readily available and inexpensive carbon sources, such as cellulose and orange peel, and a simple nutrient salt solution.