一株内生真菌的原生质体制备及再生过程研究

通过对酶系组成和酶解条件的研究,得出了制备禾本科植物内生真菌Neotyphodiumsp.原生质体的最佳条件:鲜菌丝由10.3%蔗糖溶液预处理,酶系组成为1.5%崩溃酶、1.0%蜗牛酶、1.0%纤维素酶和2.0%溶菌酶,酶解温度32℃,pH 6.8,酶解5 h,原生质体得率达7.3×103个/mg鲜菌丝.另外,液体再生涂布平板法结合钙离子作用可使原生质体再生率达4.72%,为不含钙离子处理组的2.5倍.     

Antibacterial Activity of a Novel Oligosaccharide from Streptomyces californics against Erwinia carotovora subsp. Carotovora

The present study aims to characterize and predict models for antibacterial activity of a novel oligosaccharide from Streptomyces californics against Erwinia carotovora subsp. carotovora using an adaptive neuro-fuzzy inference system and an artificial neural network. The mathematical predication models were used to determine the optimal conditions to produce oligosaccharide and determine the relationship between the factors (pH, temperature, and time). The characteristics of the purified antibacterial agent were determined using ultraviolet spectroscopy (UV/Vis), infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (¹H- and ¹³C-NMR), and mass spectrometry (MS). The best performances for the model were 39.45 and 35.16 recorded at epoch 1 for E. carotovora Erw₅ and E. carotovora EMCC 1687, respectively. The coefficient (R²) of the training was more than 0.90. The highest antimicrobial production was recorded after 9 days at 25 °C and a pH of 6.2, at which more than 17 mm of the inhibition zone was obtained. The mass spectrum of antimicrobial agent (peak at R.T. = 3.433 of fraction 6) recorded two molecular ion peaks at m/z = 703.70 and m/z = 338.30, corresponding to molecular weights of 703.70 and 338.30 g/mol, respectively. The two molecular ion peaks matched well with the molecular formulas C₂₉H₅₃NO₁₈ and C₁₄H₂₆O₉, respectively, which were obtained from the elemental analysis result. A novel oligosaccharide from Streptomyces californics with potential activity against E. carotovora EMCC 1687 and E. carotovora Erw₅ was successfully isolated, purified, and characterized.     

Optimization of alkaline protease production by Bacillus sp. using taguchi methodology

Optimization of alkaline protease production parameters by Bacillus sp. was investigated using Taguchi methodology. The pH of the medium was observed to be the most significant factor among all selected optimization parameters at an individual level. The combinatorial influence of least significant factors, inoculum level and salt solution concentration (at the individual level), resulted in an interacting severity index of 76%, suggesting their interactive role in the regulation of protease production in this microbial species. Protease production could be improved more than 100% with Taguchi’s optimized conditions of the medium composition by this microorganism.     

A Microbial Sensor Based on Direct Electron Transfer at Shewanella Sp. Drop‐Coated Screen‐Printed Carbon Electrodes

Aerobically grown Shewanella sp. bacterial suspension drop‐coated on a disposable screen‐printed carbon electrode was found to possess electroactivity without the aid of redox mediator. Cyclic voltammetric studies revealed the characteristics of a mixed diffusion adsorption‐controlled electrochemical process for direct electron transfer at the bacteria‐modified electrode. Both FE‐SEM and ATR FT‐IR experiments were carried out to investigate the surface characteristics. The electroanalytical applicability was further demonstrated for electrocatalytic reduction of arsenite, hydrogen peroxide and nitrite. Low cost and very simple manufacturing procedure allow for the proposed bacterial sensor to be applied as disposable devices.     

Medium Optimization Based on Statistical Methodologies for Pristinamycins Production by <Emphasis Type="Italic">Streptomyces pristinaespiralis</Emphasis>

The optimization of nutrient levels for the production of pristinamycins by Streptomyces pristinaespiralis CGMCC 0957 in submerged fermentation was carried out using the statistical methodologies based on the Plackett–Burman design, the steepest ascent method, and the central composite design (CCD). First, the Plackett–Burman design was applied to evaluate the influence of related nutrients in the medium. Soluble starch and MgSO₄·7H₂O were then identified as the most significant nutrients with a confidence level of 99%. Subsequently, the concentrations of the two nutrients were further optimized using response surface methodology of CCD, together with the steepest ascent method. Accordingly, a second-order polynomial regression model was finally fitted to the experimental data. By solving the regression equation from the model and analyzing the response surface, the optimal levels for soluble starch and MgSO₄·7H₂O were determined as 20.95 and 5.67g/L, respectively. Under the optimized medium, the yield of pristinamycins in the shake flask and 5-L bioreactor could reach 1.30 and 1.01g/L, respectively, which is the highest yield reported in literature to date.     

一株红树内生真菌Penicillium sp.(ZZF29#)次级代谢产物分离与鉴定

研究了一株药用红树内生真菌Penicillium sp.(ZZF29#)的次级代谢产物。用硅胶柱层析、制备薄层层析和重结晶等方法,从该菌发酵液的乙酸乙酯相中分离获得8种单体化合物,运用现代波谱技术并与文献数据对照,鉴定其结构分别为:环(苯丙-丙)二肽(1)、环(苯丙-甘)二肽(2)、环(苯丙-苯丙)二肽(3)、环(苯丙-酪)二肽(4)、大黄素(5)、大黄素甲醚(6)、麦角甾醇(7)和过氧化麦角甾醇(8)。     

韭菜有机溶剂提取液的气相色谱-质谱分析及其对香蕉枯萎病菌的抑制作用研究

采用气相色谱-质谱法对韭菜茎和叶的石油醚、三氯甲烷、二氯甲烷、丙酮、乙酸乙酯有机溶剂提取液进行了检测.结果表明:有机溶剂提取液中有二甲基二硫、二甲基三硫、甲基甲烷硫代磺酸盐、二甲基酯硫磺酸、甲基2-丙烯基二硫及杂环等多种含硫化合物,另外还检出较复杂的3-乙烯基-1,2-二硫代杂环己-5-烯类物质.低温条件下,茎中石油醚...     

不动杆菌静息细胞催化拆分外消旋环戊酮醇乙酸酯反应条件的优化

 考察了反应条件对不动杆菌Acinetobactersp．YQ231催化外消旋环戊酮醇乙酸酯对映选择性水解的反应速度和对映选择性的影响．确定的最佳酶反应条件为pH8．0，温度50℃．不同乳化剂对对映选择性的影响不同，以壬基酚聚氧乙烯醚的效果最好，当其加入量为15g／L时，反应的对映选择性最高．产物环戊酮醇对酶活性有显著的抑制作用．细胞中的酯酶优先水解（R）－环戊酮醇乙酸酯，生成（R）－环戊酮醇，在底物浓度为250mmol／L时，对映体比率（E值）可达50．     

轰击离子能量对CNx薄膜中sp3型C-N键含量的影响

对磁控溅射生长在单晶Si(001)衬底上的CNx薄膜样品的化学键合及结构进行了研究,利用不同的衬底负偏压(Vh)来控制轰击衬底表面的入射离子能量,从而影响膜中的化学键合的状态.样品的FTIR,Ra-man和XPS分析结果表明,CNx薄膜中N原子分别与sp,sp2和sp3杂化状态的C原子结合,其中sp3型C-N键含量先随着衬底偏压(Vb)的升高而增加,并在偏压Vb=-50V时达到最大值,但随着Vb继续升高,sp3型C-N键含量减少,这表明CNx薄膜中,sp3型C-N键的含量与轰击离子的能量变化密切相关.     

A New Perylenequinone from Hypomyces sp.

Some metabolites of fungi and plants containing perylenequinones have been used as folk medicine for the treatment of many diseases1,2. A filamentous fungus, Ascomy-cetes Hypocreaceae Hypomyces (Fr.) Tul. sp., was found from the northwestern mountains of Yunnan Province, and cultured successfully in the laboratory. A new perylenequinone, named hypomycin A (1), was isolated from its mycelia. In this paper the structure elucidation of 1 was described. Figure 1 The structure of compound 1 Fig…