大肠杆菌偏利共培养系统合成大豆苷元

大豆苷元是一种植物雌激素,具有多种生物活性,但在大肠杆菌中的生物全合成还未见报道。基于大豆苷元合成途径的三个模块（对香豆酸、甘草素和大豆苷元模块）,构建大肠杆菌共培养系统从头合成大豆苷元。将对香豆酸和甘草素模块分配到两株大肠杆菌中构建双菌共培养系统,合成甘草素。在此基础上,探索了三种共培养模式合成大豆苷元,结果显示,三菌共培养系统比其他两种双菌共培养系统的产量更高,达到27.8 mg/L。共培养菌株间通过苯丙氨酸的单向流动形成了偏利共生的关系,有助于平衡代谢途径,提高大豆苷元产量。该共培养系统在大肠杆菌中实现大豆苷元的从头合成,为其他黄酮类化合物的生物合成提供了即插即用的平台。     

一锅法全细胞催化合成胞苷三磷酸的研究

分别在大肠杆菌BL21(DE3)中构建胞苷激酶(CDK)与乙酸激酶(ACK)的共表达及融合表达体系和胞苷酸激酶(CMK)与乙酸激酶(ACK)的融合表达体系,其中融合菌株SUMO-CDK-L2-ACK与CMK-L2-ACK构成的双融合催化体系具有较好的催化活性。搭建了双融合菌全细胞一锅法催化合成胞苷三磷酸(CTP)反应体系,并对其温度、pH、金属离子、乙酰磷酸投加量及菌粉投加量等进行优化。结果表明,在优化反应体系中,反应75 min时CTP产量达到最高为108 mmol/L,总收率达86.4%,实现了CTP的一锅法高效合成。     

异甘草素甲苷的合成及抗氧化活性研究

以间苯二酚、冰醋酸、对甲氧基苯甲醛为原料,通过酰化、羟醛缩合反应合成异甘草素甲苷,通过~1HNMR、IR对其结构进行表征,利用其与DPPH自由基溶液的反应考察其抗氧化活性。结果表明,异甘草素标准品对DPPH自由基清除率为43.01%,异甘草素甲苷对DPPH自由基清除率为23.14%。异甘草素甲苷抗氧化活性低于异甘草素,故异甘草素的4位羟基是抗氧化活性有效部位。     

2,4,4′-三羟基苯基苄酮的合成

2,4,4′-三羟基苯基苄酮是合成大豆苷元的重要中间体,也是合成大豆苷元的技术难点,工艺路线的优劣决定大豆苷元合成方法能否工业化的关键。同时它本身有非常强的抑制酪氨酸酶活性,抑制效果较好、性质稳定、对皮肤刺激小是非常有潜力的皮肤增白剂[4]。本文论述了2,4,4′-三羟基苯基苄酮的合成方法,在原有文献的基础上,通过正交设计优化及反应溶剂的合理选取,提高了产品质量,降低了生产成本。     

氮源浓度和芳香化合物对白腐菌Panus conchatus产木素降解酶的影响

白腐菌Panusconchatus只分泌锰过氧化物酶和漆酶，不分泌术素过氧化物酶，该菌分泌这两种酶的能力大大高于同样培养基条件下的Pleuronssajor-caju。氮源浓度对Panusconchatus分泌术素降解酶的能力有显著影响，高氮条件可能是这种类型的白腐菌生产木素降解酶的必要条件。研究不同芳香化合物对Panusconchatus木素降解酶分泌情况的影响发现，紫丁香醇和香豆酸对其锰过氧化物酶和漆酶分别起显著的诱导作用。     

甘草苷的合成及抗氧化活性研究

以间苯二酚、冰醋酸、对烷氧基苯甲醛为原料,经酰化、羟醛缩合、关环反应合成了甘草苷(Ⅲ),通过~1HNMR、FTIR、MS对其结构进行了表征,并通过测定其对DPPH自由基的清除率来评价其抗氧化活性。结果表明:甘草苷具有较强的抗氧化活性,当浓度为2.00 mg·mL~(-1)时,甘草素、甘草甲苷(Ⅲa)、甘草乙苷(Ⅲb)对DPPH自由基的平均清除率分别为51.56%、44.85%、34.53%,其抗氧化活性大小为:甘草素甘草甲苷(Ⅲa)甘草乙苷(Ⅲb);甘草素的2个酚羟基为其抗氧化活性有效部位。     

对甲苯酚路线合成对羟基苯甲醛

对羟基苯甲醛是重要的有机中间体,医药上用于合成人造天麻、祛痰药杜鹃素,磺胺增效剂甲氧基苄胺嘧啶等;香料上用于合成大茴香醛;试剂上用制对羟基苯丙烯酸(对香豆酸)。用途很广,不仅内销,每年还大量向欧美国家出口。     

HPLC-DAD波长切换法同时测定逍遥丸中7种化学成分的含量

HPLC-DAD波长切换法同时测定逍遥丸中柴胡皂苷(1)、芍药苷(2)、甘草苷(3)、异甘草素(4)、甘草酸铵(5)、白术内酯Ⅲ(6)、甘草次酸(7)等7种成分的有效成分的含量,为逍遥丸的质量测定与评价提供科学依据。     

基于DFT方法研究甘草中黄酮类化合物的抗氧化活性

基于密度泛函(DFT)方法研究甘草中黄酮类化合物的抗氧化活性,对甘草素、甘草苷、异甘草素和异甘草苷4种化合物的分子结构及其相应的自由基进行了理论计算。分别在气相和溶剂中获得了4种化合物及其相应自由基的最优几何结构、NBO电荷、BDE和IP等量子化学参数。计算结果显示:4种化合物的抗氧化活性由大到小的顺序为异甘草素、异甘草苷、甘草素、甘草苷,与实验活性顺序一致,并且4种化合物中C_7位是自由基反应的最大可能活性位点。     

氮源浓度和芳香化合物对白腐菌Panus conchatus产木素降解酶…

白腐菌Ｐａｎｕｓｃｏｎｃｈａｔｕｓ只分泌锰过氧化的酶和漆酶，不分泌木素过氧化物酶。该菌分泌这两种酶的能力大大高分子同样培养基条件下的Ｐｌｅｕｒｏｔｕｓｓａｊｏｒ－ｃａｊｕ。氮源浓度对Ｐａｎｕｓｃｏｎｃｈａｔｕｓ分泌木素降解酶的能力有显著影响，高氮条件可能是这种类型的白腐菌生产木素降解酶的必要条件，研究不同芳香化合物以Ｐａｎｕｓｃｏｎｃｈａｔｕｓ木素降解酶分泌情况的影响发现，紫丁胺醛和香豆酸对其锰过     

The production of enantiopure D-lysine from L-lysine by a two-strain coupled system

The microbial production of D-lysine to replace chemical approach has gained great interest with the rising concerns over the environment. Here, we employed recombinant E. coli strain BL21-LYR with lysine racemase and strain BL-22A-RB-YB with L-lysine monooxygenase and 5-aminovaleramide amidohydrolase to establish a two-strain coupling whole-cell bioconversion system for D-lysine production from L-lysine. To improve the optical purity of D-lysine, the optimal reaction condition for resolution of DL-lysine after the racemization was investigated. The specificity of BL-22A-RB-YB for L-lysine and the effects of reaction condition on bioconversion efficiency of whole-cell were accordingly determined. Under the optimal condition, a maximum 53.5 g·L^-1 Dlysine and 48.2 g·L^-1 5-AVA were obtained with yield of 47.4% and 42.3%, respectively, by the microbial racemization and asymmetric degradation process. The final D-lysine enantiomeric excess was over 99%. Meanwhile, a valuable compound 5-aminovaleric acid was synthesized with the production of D-lysine, indicating the economic feasibility of the two-strain coupling system.     

利用E.coli评价铁碳微电解处理印染废水的生物毒性变化

印染废水的成分复杂、色度高、毒性强,通过分析E.coli (大肠杆菌)的形态、抗氧化酶和生物标志物,研究铁碳微电解工艺处理前后印染废水生物毒性的变化。结果表明:E.coli在进水中呈破碎状态,而在铁碳微电解工艺出水中的E.coli大部分为正常形态;与进水的抗氧化酶系统相比,出水组中的丙二醛(MDA)、谷胱甘肽(GSH)、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和总抗氧化能力(T-AOC)分别降低了80.85%、53.73%、67.74%、44.90%和43.38%,铁碳微电解工艺处理后的印染废水E.coli的抗氧化能力接近正常水平。进水和出水的葡萄糖消耗量抑制率分别为85%和47%;与进水的生物标志物相比,出水中热值升高21.95%,内源荧光蛋白升高112.96%,核酸含量降低44.04%。铁碳微电解工艺具有降低实际印染废水生物毒性的作用。     

重组大肠杆菌表达17β-羟基类固醇脱氢酶全细胞催化合成宝丹酮的研究

宝丹酮作为一种重要的蛋白同化雄性激素类固醇,具有提升肌肉质量和耐力的功能。宝丹酮的传统合成方法是以1,4-雄烯二酮(ADD)为底物通过化学法合成,但过程复杂、污染严重。17β-羟基类固醇脱氢酶(17β-HSD)可催化甾体化合物C-17位点的氧化还原反应,实现ADD和宝丹酮的相互转化。本研究通过基因序列同源性分析,筛选到6种不同来源的17β-HSD基因并对其在大肠杆菌中进行异源表达。利用不同重组菌转化ADD合成宝丹酮,结果表明重组菌BL21/pET28a-HSDPy的ADD转化率最高,因此选择BL21/pET28a-HSDPy进行进一步研究。鉴定了重组菌的酶学性质并优化其全细胞转化条件。结果表明在生物量为36 g·L^-1、底物浓度为5.40 g·L^-1条件下,经过两次补料,获得了3.66g·L^-1宝丹酮,比优化前提高了4.1倍。而且在生物转化过程中未检测到副产物。为生物合成宝丹酮提供了可能。     

Use of coaxial photocatalytic reactor (CAPHORE) in the TiO2 photo-assisted treatment of mixed E. coli and Bacillus sp. and bacterial community present in wastewater

This paper reports the photocatalytic disinfection of water contaminated by a mixture of Escherichia coli and Bacillus sp. as well as that of wastewater containing a larger microbial community. The photocatalytic reactions were carried out in a coaxial photocatalytic reactor called CAPHORE, using TiO₂ P-25 of Degussa. E. coli is more sensitive than Bacillus sp. to photocatalytic treatment. Bacterial inactivation was dependent on organic matter and dissolved oxygen (DO) concentration.

Of the bacterial community present in partially treated wastewater, E. coli appears to be more sensitive to the treatment than Enterococcus sp., coliforms (other than E. coli), and Gram-negative (other than coliforms). After photocatalytic treatment, no bacterial recovery of previous groups was observed for 24 h in the dark. However a very low bacterial inactivation rate was observed for the whole bacterial population present in wastewater and detected by non-selective media. The effective disinfection time (EDT), the time necessary for total inactivation of bacteria without re-growth in a subsequent dark period referenced at 24 h (or 48 h), was reached only for Enterococcus sp., and coliform groups. EDT₂₄ was not reached for the whole population.     

Photocatalytic inactivation of Escherischia coli: Effect of concentration of TiO2 and microorganism, nature, and intensity of UV irradiation

The efficiency of photocatalytic disinfection, used to inactivate Escherischia coli K12 under different physico-chemical parameters, was examined. The photocatalyst chosen was the semiconductor TiO₂ degussa P25 and the irradiation was produced by an HPK 125 lamp. The effect of titania concentration was investigated using two E. coli concentrations. The photocatalyst concentration ranged from 0.1 to 2.5 g/L. The evolution of E. coli inactivation as function of time was discussed depending on the E. coli and TiO₂ concentrations. The optimal concentration of the photocatalyst, 0.25 g/L, is lower than that necessary to absorb all photons and to degrade the organic compounds. Some hypotheses are presented to explain this behaviour. The effect of the different domains of UV light (UVA, UVB, and UVC) was also studied and modification of the light irradiation intensity is discussed. No bacteria photolysis was obtained with UVA but the use UVC had, on the contrary, a detrimental effect on bacteria survival. The addition of titania at a low concentration, 0.25 g/L, improved the inactivation of E. coli in the presence of UVA and UVB, but a detrimental effect was observed under UVC. The disinfection efficiency increases as a function of light intensity, whatever the photocatalytic conditions (different TiO₂ concentrations and different UV domains). No bacterial growth was observed after disinfection, whether the system contained titania or not.     

EVALUATION OF UV DOSE IN FLOW-THROUGH REACTORS FOR FRESH APPLE JUICE AND CIDER

High absorptivity and turbidity interfere with the UV disinfection of apple cider. Three different configurations of flow-through UV reactors were evaluated to overcome this interference. Two approaches were employed: use of an extremely thin film UV reactor and increasing the turbulence within a UV reactor. Multiple-lamp UV reactors including the thin-film laminar flow “CiderSure” (8 lamps) and turbulent flow “Aquionics” (12 lamps) and annular single-lamp “UltraDynamics” reactor were studied. UV disinfection performance in laminar and turbulent flow reactors was compared by evaluation of UV dose delivery. UV fluence rate (irradiance) distribution was calculated using the multiple point source summation method. E. coli K12 was used as a target bacterium in a bioassay, and the log reduction per one pass was determined for each UV reactor. Finally, the UV decimal reduction dose (D₁₀) was calculated by dividing the average UV fluence by log bacterial reduction per pass. Variations of the UV decimal dose were observed with various designs of UV systems. The least inactivation of E. coli K12 but the highest UV decimal reduction dose, ranging from 90 to 150 mJ/cm², was observed in the Aquionics UV reactor in apple cider with apparent absorption coefficient (a) of 5.7 mm^-1. The lower value of UV decimal reduction dose of 7.3-7.8 mJ/cm² was required for inactivation of E. coli K12 in malate buffer and apple juice in the annular single-lamp UltraDynamics reactor. However, the decimal reduction dose for E. coli K12 in apple cider was significantly higher, about 20.4 mJ/cm². Similar UV decimal reduction doses from 25.1 to 18.8 mJ/cm² for inactivation of E. coli K12 were observed in the thin-film 'CiderSure' UV reactor in apple cider with identical absorption coefficient. Mathematical modeling of UV irradiance can improve the evaluation of UV dose delivery and distribution within the reactors.     

改性黄腐酸/凹凸棒石复合材料的制备及其抑菌性能

黄腐酸(FA)具有抑菌消炎和促进动物生长的功效。为了进一步提升FA的广谱抑菌性,以凹凸棒石(APT)为载体,通过吸附法将FA负载于APT,同时进行十六烷基三甲基溴化铵(CTAB)改性。结果表明,FA和APT主要以静电吸附形式结合,CTAB的引入实现了FA/APT复合材料的电荷调控。复合材料对大肠杆菌和金黄色葡萄球菌的最小抑菌浓度(MIC)随着CTAB添加量的增加而减小;当CTAB添加量为15%(质量分数)时,其对大肠杆菌的MIC为1 mg/mL,对金黄色葡萄球菌的MIC为0.05 mg/mL。     

Catalytic wet oxidation of p-coumaric acid: Partial oxidation intermediates, reaction pathways and catalyst leaching

The catalytic oxidation of p-coumaric acid, a compound representative of the polyphenolic fraction typically found in olive processing and wine-distillery wastewaters, has been investigated using various homogeneous and heterogeneous catalysts. Experiments have been performed with homogeneous Fe²⁺, Cu²⁺, Zn²⁺ and Co²⁺ ions at pH = 1, and with metal oxide catalysts in suspension at pH 3.5, 7 and 12. Additional uncatalyzed experiments have been performed and the results are compared to those of the catalyzed runs. The temperature was 403 K and the oxygen partial pressure was 2.8 MPa in all runs. The distribution of the reaction intermediates was determined, using HPLC and GCMS as the main analytical techniques, and reaction pathways are speculated. It was found that the use of catalysts could increase the rate of destruction of p-coumaric acid compared to the uncatalyzed reaction, while the distribution of the intermediate compounds was strongly dependent on the pH of the solution. A CuO·ZnOAl₂O₃ heterogeneous catalyst was found to be effective for the oxidation of p-coumaric acid although leaching of dissolved metals to the solution was found to occur. The stability of the heterogeneous catalysts was investigated by measuring the extent of metal leaching into the solution. The results are discussed with respect to the impact of various conditions (catalyst, pH) on the oxidation of p-coumaric acid and compared to those of the uncatalyzed reaction, studied in previous work.     

Cyanobacterial photo-driven mixotrophic metabolism and its advantages for biosynthesis

Cyanobacterium offers a promising chassis for phototrophic production of renewable chemicals. Although engineered cyanobacteria can achieve similar product carbon yields as heterotrophic microbial hosts, their production rate and titer under photoautotrophic conditions are 10 to 100 folds lower than those in fast growing E. coli. Cyanobacterial factories face three indomitable bottlenecks. First, photosynthesis has limited ATP and NADPH generation rates. Second, CO₂ fixation by ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) has poor efficiency. Third, CO₂ mass transfer and light supply are deficient within large photobioreactors. On the other hand, cyanobacteria may employ organic substrates to promote phototrophic cell growth, N₂ fixation, and metabolite synthesis. The photo-fermentations show enhanced photosynthesis, while CO₂ loss from organic substrate degradation can be reused by the Calvin cycle. In addition, the plasticity of cyanobacterial pathways (e.g., oxidative pentose phosphate pathway and the TCA cycle) has been recently revealed to facilitate the catabolism. The use of cyanobacteria as “green E. coli” could be a promising route to develop robust photo-biorefineries.