硫循环的酶促反应机制及湖泊环境效应

在湖泊沉积物表层存在着强烈的生物作用 ,使SO2 -4 转变成S2 -,然后和Fe2 + 结合而固定在沉积物中 ,这种SO2 -4 的清除机制具有重要的环境意义。本文论述了H2 S的产生和各种形态硫转变成SO2 -4 的酶促反应机制 ,并阐述了不同微生物电子传递载体、最终电子受体和电子进入传递链的部位的差异以及生成ATP的数目和环境效应的差异。     

Enzymatic hydrolysis of banana stems (Musa acuminata): Optimization of process parameters and inhibition characterization

In current work, an optimum solid loading (solid: liquid = 1:20), pH (4.8), temperature (50°C), and enzyme dosing of 20 filter paper unit (amount of enzyme required to release 1 µmol of glucose as reducing sugar from filter paper in per mL per minute) were enumerated for enzymatic hydrolysis of banana stem using cellulase from Trichoderma reesei. Further, inhibition study on enzymatic hydrolysis of banana stem was investigated by the supplementation of monosaccharides (glucose, galactose, mannose, xylose, and arabinose), disaccharide (cellobiose), and inhibitors (acetic acid and furfural obtained from pre-enzymatic hydrolysis steps). Glucose and cellobiose showed inhibitory effect on enzymatic hydrolysis of pretreated banana stem at or above 8 g/L while galactose, mannose, and xylose showed a significant inhibitory effect at or above 4 g/L. Instead of inhibition, arabinose enhanced the enzymatic hydrolysis with increase in total reducing sugars. Acetic acid did not show any significant inhibition while furfural inhibited the system at a comparative low concentration of 2 g/L. Further, scanning electron microscopy analysis was performed to investigate the difference in ultra-structural morphology of raw biomass, pretreated biomass, and biomass obtained after enzymatic hydrolysis.     

降解剩余污泥中纤维素/半纤维素微生物富集培养实验研究

为促进剩余污泥中木质纤维素能源转化,首先需要探知污泥中是否存在可以降解纤维素/半纤维素的微生物.以木聚糖作为单一碳源分别从剩余污泥和厌氧消化污泥中富集培养可降解纤维素/半纤维素的微生物.实验结果显示,两种污泥源中均存在可降解纤维素/半纤维素的微生物,并可成功富集培养获得该类微生物.FISH与LIVE/DEAD实验证实,富集微生物为梭状芽孢杆菌属和芽孢杆菌属的混合物,并以梭状芽孢杆菌为主;富集微生物均具有很高活性.     

磁性Fe3O4/石墨烯异质结固定漆酶特性及其对水中双酚A的降解研究

以磁性石墨烯为载体制备了磁性石墨烯固定化漆酶,考察了固定化漆酶的酶学特性及其对双酚A（BPA）的降解效能。结果表明,氧化石墨烯的比表面积高达726.34 m2·g-1,与游离漆酶相比,经过石墨烯固定化后漆酶对酸的适应能力、耐热性和贮存稳定性均有所提高,pH值2.0~4.0范围内固定化漆酶活性较为稳定;加入变性剂尿素（1 mol·L-1）后,固定化漆酶的相对活性为87%,游离漆酶相对活性仅为63.02%,固定化导致抗变性剂能力增强。固定化漆酶和游离漆酶活性分别在45和40℃时达到最大值。与游离漆酶相比,固定化漆酶最佳反应温度升高了5℃,且在50℃时,固定化漆酶的相对活性依然保持在95.11%;25℃,pH值4.0条件下保存10 d,固定化漆酶活性为最初活性的82.57%;固定化漆酶具有良好的重复利用性,重复利用10次后,漆酶活性仍为最初活性的82.01%。固定化酶的米氏常数Km为5.38×10-4 mol·L-1,较游离酶的大,说明固定化酶与底物的亲和力比游离酶小。磁性石墨烯固定化漆酶具有良好的吸附能力,可吸附-催化氧化水中的 BPA,且石墨烯良好的吸附作用促进了催化反应,水中BPA质量浓度为15 mg·L-1时,经过18 h反应,BPA的去除率能达到82.14%左右。本研究的结果为石墨烯新型材料固定化漆酶及其应用提供了参考。     

Production, Purification and Activity of an Extracellular Depolymerase from Aspergillus fumigatus

A strain of Aspergillus fumigatus, which was observed to rapidly degrade poly-3-hydroxybutyrate (PHB) in a leaf compost, was found to secrete an extracellular hydrolase when grown on PHB as the sole carbon source. Isolation and characterization of the PHB hydrolase (depolymerase) from this fungus revealed that the enzyme had a molecular weight of 57 kDa, an isoelectric point of 7.2, and a PHB hydrolysis activity maxima which occurred at 70°C and pH 8.0. Affinity labeling experiments suggested that this fungal hydrolase is a type of serine esterase. The cyclic trimers of 3-hydroxybutyrate were found to reversibly inhibit the enzymes.     

Biosynthesis and Characterization of Laccase Catalyzed Poly(Catechol)

Enzymatic polymerization of catechol was conducted batch-wise using laccase enzyme produced by the culture Trametes versicolor (ATCC 200801). The polymerization reaction was carried out in 1:1 (v/v) aqueous-acetone solution, buffered at pH 5.0 with sodium acetate (50 mM) in a sealed, temperature-controlled reactor at 25°C. The molecular weight of the produced polymer was determined with GPC. FT-IR, DSC, and TGA were employed to investigate the structure and thermal behavior of synthesized poly(catechol). It was found that catechol units were linked together with ether bonds and thermal stability of the catechol increased in the poly(catechol) polymeric structure effectively. The number average molecular weight of poly(catechol) was found as 813 ± 3 Da with a very narrow polydispersity value of 1.17 showing selective polymerization of catechol by the enzyme.     

生化——光催化氧化法处理苎麻脱胶废水

工程实践表明，采用生化与光催化氧化相结合的工艺处理苎麻脱胶废水，具有处理效果好、运行稳定、运行费用低等特点。     

Start-up performances of dry anaerobic mesophilic and thermophilic digestions of organic solid wastes

Two dry anaerobic digestions of organic solid wastes were conducted for 6 weeks in a lab-scale batch experiment for investigating the start-up performances under mesophilic and thermophilic conditions. The enzymatic activities, i.e., β-glucosidase, N-α-benzoyl-Largininamide （BAA）-hydrolysing protease, urease and phosphatase activities were analysed. The BAA-hydrolysing protease activity during the first 2-3 weeks was low with low pH, but was enhanced later with the pH increase. β-Glucosidase activity showed the lowest values in weeks 1-2, and recovered with the increase of BAA-hydrolysing protease activity. Acetic acid dominated most of the total VFAs in thermophilic digestion, while propionate and butyrate dominated in mesophilic digestion. Thermophilic digestion was confirmed more feasible for achieving better performance against misbalance, especially during the start-up period in a dry anaerobic digestion process.     

降解菌CDS-1产呋喃丹水解酶的条件及酶学特征

Sphingomonas sp.CDS-1是一株呋喃丹高效降解菌.为了给利用该菌产生的酶去除环境中的呋喃丹残留提供一些理论依据,对CDS-1产生的呋喃丹水解酶粗酶进行了研究.结果表明,在LB培养基中,CDS-1产生呋喃丹水解酶的最适条件为pH6～8、30℃、培养30h;该酶在20～30℃、pH>6.0的条件下比较稳定;在pH6.5和30℃时显示最大的呋喃丹水解酶活性;大多数金属离子浓度在0.2mmol/L时对其酶活有促进作用;酶定域实验结果显示该酶为胞内酶.     

Biochemical composition and early diagenesis of organic matter in coastal sediments of the NW Adriatic Sea influenced by riverine inputs

River inputs influence trophodynamic and biogeochemical processes of adjacent continental shelves. In order to provide new insights on the influence of continental inputs on the benthic trophic state and early diagenesis of sediment organic matter we collected surface sediments in the NW Adriatic Sea at three stations located at increasing distance from the Po River. Sediment samples were collected in four periods characterized by different river outflows and analysed for chloropigment content (chlorophyll-a and phaeopygments), protein, carbohydrate and lipid concentrations, prokaryote abundance and aminopeptidase activity. Sediments of the NW Adriatic Sea displayed high organic loads, tightly coupled with the outflow dynamics of the Po River. A major flooding event was responsible of an enhanced accumulation of organic material on the sea bottom. The resulting increased nutrient load in the sediment impaired organic matter degradation processes. The results of the present study suggest that the enhanced trophic state of marine coastal sediments subjected to riverine inputs are related not only to the increased nutrient inputs, but that they may be amplified by impaired degradation processes.