短梗霉最佳培养条件研究

本文针对短梗霉多糖高产菌N518号菌株在发酵时的营养、初始pH值、温度和氧气等发酵条件的需求进行了研究．利用五因素四水平的正交试验获得了蔗糖等五种营养成份的最佳组合及最适的培养条件．结果表明，在本研究的条件下该菌蔗糖的转化率可达到56.2％．     

出芽短梗霉积累聚苹果酸途径及调控研究

引言聚苹果酸[poly(β-malic acid),PMLA]是新近开发的一种生物高聚物,因其良好的水溶性、生物可降解性、生物相容性以及易代谢性[1]、易修饰性[2],PMLA及其衍生物在生物医用材料、化妆     

短梗霉多糖的生产及应用开发

短梗霉多糖(Pullulan)又称卜多糖，是由出芽短梗霉(Aureobasidium Pullulans)产生的一种水溶性胞外多糖，系中性的大分子聚合物，分子量一般在10^4-10^5的范围内。是以碳水化合物(淀粉、蔗糖等)为主要原料，通过“微生物发酵-分离、纯化-干燥”等进行工业生产获得商业产品。短梗霉多糖具有独特的物理化学和生物学性质，在医药制造、食品包装、果品及食品保鲜、粘结等方面有广泛的用途，是一种多功能的新型生物制品，具有广阔的应用开发前景。     

康氏木霉的原生质体诱变

康氏木霉作为出发菌株,用溶壁酶对菌丝体进行破壁,提取原生质体再用紫外线做诱变处理,经多次筛选,从中选出一株酶活较高菌株,其FP酶活为36.2g/minmL,是原菌酶活的2.41倍。     

对溴联苯基乙酮的合成

由联苯经溴化,乙酰化合成化工中间体对溴联苯基乙酮,总收率为５３％。     

利用响应面法优化出芽短梗霉As3．933产普鲁兰多糖发酵培养基

采用响应面分析法对出芽短梗霉As3．933产普鲁兰多糖的发酵培养基进行优化。首先利用Plackett-Bur-man实验筛选出影响普鲁兰多糖产量的主要因素为酵母膏、（NH4）zSO4和K2HPO4,再利用最陡爬坡实验逼近最大响应区域,最后通过Box-Behnken实验并运用Design-Expert8．0软件优化发酵培养基。确定优化培养基组成为：蔗糖62．5g·L-1,（NH4）2S040．67g·L-1,酵母膏2．84g·L-1,K2HPO47．12g·L-1,NaCl1．25g·L-1,MgS04·7H200．25g·L-1,pH值6．5,优化后的普鲁兰多糖产量达到22．29g·L-1,较初始液体发酵培养基（17．32g·L-1）提高了28．70％。     

利用动力学模型探讨碳源浓度对普鲁兰分批发酵过程的影响

采用Logistic、Luedeking-Piret以及Luedeking-Piret修正模型分别建立了不同初始蔗糖浓度下Aureobasidium pullulans(swp35)分批发酵生产普鲁兰过程中的菌体生长、产物积累和基质消耗的数学模型,并采用1stopt软件,选取修正高斯牛顿法和通用全局优化算法进行非线性曲线拟合,计算获得动力学模型参数。研究结果表明:上述模型能较好地反映本研究实验条件下swp 35的细胞生长、产物合成和底物消耗过程,拟合动力学模型的相关系数R2均大于0.91;普鲁兰合成与细胞生长基本呈偶联关系;初始蔗糖浓度对菌体合成速率有明显的抑制作用:随着初始蔗糖浓度从25 g/L增加到100 g/L,最大比生长速率从0.146 h-1下降到0.049 h-1;最大比产物生成速率和比底物吸收速率在50 g/L初始蔗糖浓度时呈现峰值,分别达到0.536 h-1和0.844 h-1。从文章研究结果可知,以50 g/L蔗糖为初始浓度分批补料发酵生产普鲁兰可能比分批发酵方式更高效。     

杀菌剂乙霉威的合成方法研究

以邻苯二乙醚为主要原料,经混酸硝化后催化加氢还原,得中间体对氨基邻苯二乙醚,再与氯甲酸异丙酯缩合,得到乙霉威。结果表明,催化加氢还原的最佳条件:反应温度90℃,催化剂用量为反应物质量的3%,压力1.5 MPa,反应时间3 h;缩合反应的最佳条件:以三乙胺为缚酸剂,溶剂甲苯与反应物的质量比为2.1∶1,对氨基邻苯二乙醚与氯甲酸异丙酯的摩尔比为1∶1.3,反应时间0.5 h。在较佳的反应条件下,乙霉威的总收率≥80.38%,含量≥98%。     

乙霉威的原位薄层荧光色谱分析方法研究

介绍了用DNS -Cl作为荧光衍生试剂 ,研究了乙霉威的原位薄层荧光色谱扫描微量分析方法。该方法操作简便、灵敏度高、选择性好、专属性强。样品在 1 0～ 50 0ng/点之间有良好的线性关系 ,最低检出限量为 0 .5ng/点。回收率为 94 .52 %～ 1 0 1 .39%。     

Influence of culture pH and aeration on ethanol production and pullulan molecular weight by Aureobasidium pullulans

The formation of ethanol by the polymorphic fungus Aureobasidium pullulans was examined under a range of culture pH values and aeration conditions. Although culture pH had a profound effect on fungal morphology, with a greatly increased proportion of the biomass in the unicellular (yeast-like) form at pH 6·5, there appeared to be no direct link between morphological form and ethanol formation. The levels of ethanol noted may have influenced the morphology. Cessation of aeration rapidly led to a halt in growth and exopolysaccharide synthesis, while ethanol synthesis proceeded rapidly. The ethanol formed could be re-oxidised under conditions where the available carbon source was depleted. Two distinct exopolysaccharides of different molecular weights were recovered from the culture fluids. Overall, the molecular weight of both declined with process time.     

Optimization of pullulan production using Ca‐alginate‐immobilized Aureobasidium pullulans by response surface methodology

BACKGROUND: The production of pullulan from synthetic medium by Aureobasidium pullulans P56 immobilized in Ca‐alginate beads was investigated using batch and repeated batch fermentation systems. RESULTS: The highest pullulan concentration (19.52 ± 0.37 g dm^?3) was obtained with 2.0‐2.4 mm beads prepared from 2% sodium alginate solution. Pullulan production was mainly accomplished by immobilized fungal cells since leaked cells in the fermentation medium comprised 17.4% of the total fungal population at the end of fermentation. The pullulan proportion was 84.5% of the total polysaccharide in the fermentation medium. Response surface methodology was used to investigate the effects of three fermentation parameters (initial pH, agitation speed and incubation time) on the concentration of pullulan. Results of the statistical analysis showed that the fit of the model was good in all cases. The maximum pullulan concentration of 21.07 ± 0.48 g dm^?3 was obtained at the optimum concentrations of process variables (pH 7.31, agitation speed 191.5 rpm, incubation time 101.2 h). The gel beads produced pullulan under the optimized conditions for six consecutive batch fermentations without marked activity loss and deformation. CONCLUSION: The results of this study suggest that the immobilization of A. pullulans cells in Ca‐alginate gel beads is suitable for batch and repeated batch production of pullulan. Copyright © 2007 Society of Chemical Industry     

Effect of the aeration rate on pullulan production and fermentation broth rheological properties in an airlift reactor

The effect of aeration rate on pullulan production and the rheological properties of the fermentation broth in an airlift reactor was investigated. An airlift fermenter was shown to be an appropriate fermentation system for the production of pullulan. A maximum pullulan concentration (30 kg m^?3), biomass concentration (6.0 kg m^?3), pullulan yield (60%, w/w) and sugar utilization (100%, w/w) was obtained at an aeration rate of 2 vvm. The mycelium and the yeast‐like cells were the morphological forms responsible for pullulan production. The highest polysaccharide concentration was obtained when the mycelial forms and the yeast‐like cells were 60% and 40% (w/w) of the total biomass, respectively. The apparent viscosity of the broth was increased with the increase of the aeration rate from 1 to 2 vvm and then decreased at higher vvms. On the other hand, the dissolved oxygen concentration and the volumetric mass transfer coefficient continually increased with the increase of the aeration rate. The mycelial forms and the production of extracellular polysaccharide were responsible for the non‐Newtonian flow behaviour of the fermentation broth. The rheological behaviour can be characterized by a power law type of equation. The relationship between shear rate/shear stress and shear rate/apparent viscosity showed a non‐Newtonian behaviour of the fermentation broth. © 2001 Society of Chemical Industry     

Optimization of pullulan production from synthetic medium by Aureobasidium pullulans in a stirred tank reactor by response surface methodology

The production of pullulan from synthetic medium by Aureobasidium pullulans P56 in a stirred tank fermenter was investigated. The kinetics of polysaccharide, pullulan and biomass production was determined. Response surface methodology was used to investigate the effects of three factors (initial sugar concentration, aeration rate and agitation speed) on the concentration of pullulan in batch cultures of A pullulans. In the experiments, the range of values used for the three variables described were; 30–70 g dm^?3 initial sugar concentration, 200–600 rpm agitation speed and 1.0–3.0 vvm aeration rate. No previous work has used statistical analysis in determining the interactions among these variables in pullulan production. Results of the statistical analysis showed that the fit of the model was good in all cases. Aeration rate, agitation speed and sugar concentration had a strong linear effect on pullulan concentration. Moreover, pullulan concentration was significantly influenced by the negative quadratic effects of the given variables and by their positive or negative interactions with the exception that the interaction between agitation speed and aeration rate was insignificant (P > 0.05). Maximum pullulan concentration of 17.2 g dm^?3 was obtained at the optimum levels of process variables (initial sugar concentration 51.4 g dm^?3, aeration rate 2.36 vvm, agitation speed 345.3 rpm). These values were obtained by fitting of the experimental data to the model equation. Scanning electron microscope (SEM) photographs of polysaccharide particles containing different concentrations of pullulan were also taken to observe the morphological differences of the samples. Copyright © 2005 Society of Chemical Industry     

溴乙酰溴中二溴乙酰溴杂质分析方法的研究

建立了间接测定溴乙酰溴中二溴乙酰溴含量的HPLC方法。将溴乙酰溴水解生成溴乙酸,辅以LC-MS技术,对其主要杂质进行定性研究。采用十八烷基硅烷键合硅胶柱,流动相为V(10 mmol/L三乙胺溶液)∶V(乙腈)=95∶5,检测波长为205 nm。溴乙酸与二溴乙酸在0.001~1.0 mg/mL浓度范围内线性关系良好,平均回收率为99.3%,RSD为0.87%,二溴乙酸相对校正因子为0.37。高效液相色谱法与离子色谱法测定结果一致,方法准确可靠,适于对溴乙酰溴原料中二溴乙酰溴杂质的控制。