黑曲霉SL2-111复合酶固体发酵工艺研究

以酸性蛋白酶酶活为响应值,采用单因素搜索和正交试验对黑曲霉（Aspergillus niger）SL2－111固体发酵工艺进行优化,结果表明最适培养基的组成为：新鲜麸皮8．25g,米糠4．5g、豆饼粉1．5g、（NH4)2SO40.3g、K2HPO40．66g、CaCl20.075g、水8．6mL,pH5．5,变温培养,前30h28℃、后30h为23℃,培养时间为60h。采用最适培养基和优化工艺,在250mL三角瓶中进行验证实验,酸性蛋白酶酶活可达12586U/g,果胶酶和纤维素酶分别为16490U/g、9822U／g。     

Vive la variance: a functional oviposition theory for insect herbivores

We developed state-dependent life-history theory to explain the variance in clutch size decisions made by insect herbivores under a variety of ecological scenarios. An important aspect of our theory is explicit representation of the distribution of host quality and frequency of occurrence. Examination of the theory suggests that clutch size decisions can be highly non-linear with respect to host quality and variability. We then use our theory to explore the potential for bet-hedging strategies to evolve as a function of unpredictable catastrophic events that decimate entire clutches. Our analysis suggests that the benefits to employing such a strategy will frequently be outweighed by costs brought on by delayed oviposition.     

过氧化氢酶基因在大肠杆菌中的克隆表达及发酵优化

利用PCR扩增技术得到枯草芽孢杆菌(Bacillus subtilis)过氧化氢酶基因katA,将该基因与表达载体pET-20b(+)连接构建重组质粒,经测序验证后,在大肠杆菌JM109中进行表达得到重组大肠杆菌基因工程菌E.coli BL21(DE3)(pET-20b(+)-katA).SDS-PAGE电泳结果显示出...     

利用模拟退火算法优化Biome-BGC模型参数

生态过程模型建立在明确的机理之上,能够较好地模拟陆地生态系统的行为和特征,但模型众多的参数,成为模型具体应用的瓶颈。本文以Biome-BGC模型为例,采用模拟退火算法,对其生理、生态参数进行优化。在优化过程中,先对待优化参数进行了选择,然后采取逐步优化的方法进行优化。结果表明,使用优化后的参数,模型模拟结果与实际观测更为接近,参数优化能有效地降低模型模拟的不确定性。文中参数优化的过程和方法,可为生态模型的参数识别和优化提供一种实例和思路,有助于生态模型应用区域的扩展。     

1株阿魏酸酯酶产生菌的筛选鉴定及发酵条件优化

从浙江绍兴鉴湖附近土样中分离筛选到1株产阿魏酸酯酶(ferulic acid esterase,FAE)的菌株FD-8,通过菌落形态、分生孢子梗形态对比和ITS/18S rDNA分子生物学同源性分析,鉴定该菌株为溜曲霉,命名为Aspergillus tamarii FD-8。FD-8生长最适碳源和氮源分别为蔗糖和酵母浸提物,最适生长温度和pH分别为32℃和5.0,最适产酶条件为32℃、pH 6.0,发酵周期为120 h。在最适培养基中、分阶段控制pH培养条件下,FAE比酶活达到231.34 mU/mg。去淀粉麸皮可诱导FAE的合成,在发酵48 h添加20.0 g/L去淀粉麸皮,FAE最高比酶活可达到573.61 mU/mg,比对照提高1.48倍。     

Effects of temperature and glycerol and methanol‐feeding profiles on the production of recombinant galactose oxidase in Pichia pastoris

Optimization of protein production from methanol‐induced Pichia pastoris cultures is necessary to ensure high productivity rates and high yields of recombinant proteins. We investigated the effects of temperature and different linear or exponential methanol‐feeding rates on the production of recombinant Fusarium graminearum galactose oxidase (EC 1.1.3.9) in a P. pastoris Mut⁺ strain, under regulation of the AOX1 promoter. We found that low exponential methanol feeding led to 1.5‐fold higher volumetric productivity compared to high exponential feeding rates. The duration of glycerol feeding did not affect the subsequent product yield, but longer glycerol feeding led to higher initial biomass concentration, which would reduce the oxygen demand and generate less heat during induction. A linear and a low exponential feeding profile led to productivities in the same range, but the latter was characterized by intense fluctuations in the titers of galactose oxidase and total protein. An exponential feeding profile that has been adapted to the apparent biomass concentration results in more stable cultures, but the concentration of recombinant protein is in the same range as when constant methanol feeding is employed. © 2014 The Authors Biotechnology Progress published by Wiley Periodicals, Inc. on behalf of American Institute of Chemical Engineers Biotechnol. Prog., 30:728–735, 2014     

An improved neutral landscape model for recreating real landscapes and generating landscape series for spatial ecological simulations

Many studies have assessed the effect of landscape patterns on spatial ecological processes by simulating these processes in computer‐generated landscapes with varying composition and configuration. To generate such landscapes, various neutral landscape models have been developed. However, the limited set of landscape‐level pattern variables included in these models is often inadequate to generate landscapes that reflect real landscapes. In order to achieve more flexibility and variability in the generated landscapes patterns, a more complete set of class‐ and patch‐level pattern variables should be implemented in these models. These enhancements have been implemented in Landscape Generator (LG), which is a software that uses optimization algorithms to generate landscapes that match user‐defined target values. Developed for participatory spatial planning at small scale, we enhanced the usability of LG and demonstrated how it can be used for larger scale ecological studies. First, we used LG to recreate landscape patterns from a real landscape (i.e., a mountainous region in Switzerland). Second, we generated landscape series with incrementally changing pattern variables, which could be used in ecological simulation studies. We found that LG was able to recreate landscape patterns that approximate those of real landscapes. Furthermore, we successfully generated landscape series that would not have been possible with traditional neutral landscape models. LG is a promising novel approach for generating neutral landscapes and enables testing of new hypotheses regarding the influence of landscape patterns on ecological processes. LG is freely available online.     

桐粮间作林带的配置方式与农作物产量关系的研究

以桐粮间作为例,研究了林带的不同配置结构、林带冠覆盖率及小麦产量之间的关系。结果表明,林带距（Ｘｄ）、小麦相对产量（Ｙ）及间作年（Ａ）之间的关系为：Ｙ＝９０．３２９０－１．９９８２Ａ＋１．１９２４Ｘｄ－０．３３４９Ａ＾２＋０．２９１０ＡＸｄ－０．００３２ＡＸｄ＾２;林带冠覆盖率（Ｘｃ）与小麦相对产量（Ｙ）之间的关系为：Ｙ＝－０．０４６Ｘｃ＾２＋１．１５３９Ｘｃ＋９８．１７３（Ｘｃ≤２８％）,Ｙ＝ｅ