烟曲霉A-16产纤维素酶工艺优化及酶学特性北大核心CSCD

分离筛选高效降解稻草的菌株,研究菌株产纤维素酶工艺条件及酶学性质。采用刚果红染色法从腐败木质下的土壤中分离筛选到一株产纤维素酶菌株,结合菌株的形态特征和18S rDNA序列同源性比较进行鉴定;通过单因素试验和响应面分析法确定菌株最适产酶条件,并对纤维素酶的稳定性进行研究。分离纯化得到的菌株命名为烟曲霉(Aspergillus fumigatus A-16);响应面实验结果表明,最优产纤维素酶工艺参数为:稻草粉添加量7 g/100 mL,pH 6.0,温度65℃,发酵时间5 d;在此最优条件下,该菌产生的羧甲基纤维素酶(CMCase)和滤纸酶(FPA)活力分别为2 954.76 U/mL和1 086.37 U/mL;其总活力较优化前提高了26.4%。该纤维素酶的适宜反应温度为70℃,适宜pH 6.0。在80℃热处理90 min条件下酶活力可保持在80%以上,说明该酶热稳定性较好。同时,在pH 5.0-7.0范围内比较稳定,放置1 d后可保持70%以上的酶活力。该研究可为利用富含纤维素的生物质原料开发洁净能源及食品级葡萄糖资源提供了基础支撑。     

家蚕肠道环境对外源纤维素酶活力稳定性影响的研究

纤维素酶对家蚕消化桑叶纤维素起重要生理作用,本试验研究了不同温度、pH对外源纤维素酶活力的影响及纤维素酶的热稳定性与pH稳定性,同时在模拟家蚕肠道环境条件下,研究了纤维素酶活力的稳定性。结果表明：所选的外源纤维素酶在家蚕肠液中的最适催化温度为30℃左右,最适pH为8．0左右;酶在家蚕体温范围内具有较好的稳定性,在pH8．0-10．0范围内酶活力较稳定;模拟家蚕肠道环境条件下酶活力稳定性实验表明,在80min时间内,纤维素酶能够保持较高的活力而发挥生物活性。     

高碱性纤维素酶产生菌的筛选及鉴定

从化纤厂土样中分离得到菌株AC-4,碱性纤维素酶活力达0.602 IU/mL。通过分析菌株形态学特性、培养特征及16S rDNA序列,确定该菌株为短小芽孢杆菌。对该菌所产碱性纤维素酶的酶学性质进行测定,确定其最适作用pH为9.5,最适作用温度为50℃。     

产碱性纤维素酶兼性厌氧菌株的筛选和酶学性质的初步研究

用CMC平板筛选方法, 从造纸厂碱性土壤中获得产碱性纤维素酶兼性厌氧菌株LZ-5, 革兰氏阴性, 经鉴定为弧菌属(Vibrio sp.)中的一个种。液体摇瓶培养产生碱性纤维素酶活力高达5.8 U/mL。酶学性质初步研究显示, LZ-5产生的纤维素酶最适反应温度为40℃, 最适反应pH值为9.0, 在碱性条件下具有较高的酶活性和较好的稳定性。经传代培养证实该菌株遗传性能稳定。     

产碱性纤维素酶兼性厌氧菌株的筛选和酶学性质的初步研究

用CMC平板筛选方法,从造纸厂碱性土壤中获得产碱性纤维素酶兼性厌氧菌株LZ-5,革兰氏阴性,经鉴定为弧菌属(Vibrio sp.)中的一个种.液体摇瓶培养产生碱性纤维素酶活力高达5.8 U/mL.酶学性质初步研究显示,LZ-5产生的纤维素酶最适反应温度为40℃,最适反应pH值为9.0,在碱性条件下具有较高的酶活性和较好的稳定性.经传代培养证实该菌株遗传性能稳定.     

一株来源于土壤的横梗霉菌及其产羧甲基纤维素酶性质

从广州徐闻农垦丰收农场土壤样品中分离到一株产羧甲基纤维素酶菌株,结合菌株形态特征和ITS基因序列同源性分析结果,表明该菌株为Lichtheimia sp.的未定种,其系统分类学关系与横梗霉菌Lichtheimia ramosa isolate K12(MN190291.1)最近,故命名为:横梗霉菌XWNR1(Lichtheimia ramosa XWNR1),该菌种保藏号为CCTCC NO:M2018230。采用刚果红染色法发现该菌粗酶液能够降解羧甲基纤维素钠产生透明圈,初步确定该菌具有产羧甲基纤维素酶的能力。通过优化该菌发酵培养条件,结果表明:该菌株以2.0×10^6接种浓度、1%接种量,28℃180 r/min恒温振荡培养60 h时,菌株分泌的羧甲基纤维素酶具有最好的活力。酶学性质初步研究结果表明,该羧甲基纤维素酶在最适pH 7.0、最适反应温度40℃条件下具有较好的pH稳定性和热稳定性。     

产碱性纤维素酶嗜碱芽孢杆菌AH-8的研究

从贵州、云南、海南、安徽、四川、辽宁等地采集碱性土样,分离筛选到1株能稳定的产生碱性纤维素酶的嗜碱性芽孢杆菌AH-8。研究表明,该菌株最适产酶温度为37℃,最适发酵时间为36 h;采用均匀设计法对其发酵培养基进行优化,优化培养基配方(%):淀粉3.0,胰蛋白胨1.5,牛肉膏1.5,葡萄糖0.3,KH2PO40.1,初始pH 10.0。在优化培养基条件下,其产酶量提高了120%。碱性纤维素酶最适反应温度为60℃;最适反应pH 10.0;0.01%Co2 对酶活力有一定激活作用。     

产低温纤维素酶放线菌的筛选、鉴定及酶学性质初步研究

从青藏高原采集的牦牛粪中,经过CMC平板分离得到一株产低温纤维素酶能力较强的放菌Tibet-YD5227-2,经16S rDNA序列比对分析将其初步鉴定为链霉菌属(Streptomyces sp.),目前尚无链霉菌产低温纤维素酶的研究报道。Tibet-YD5227-2液体摇瓶培养产生低温CMC酶活力高达145U/mL,最适产酶温度25℃,最适产酶pH值为8.0。酶学性质初步研究显示,Tibet-YD5227-2产生的CMC酶反应温度以35℃左右为适,反应的pH值以8.0左右为适,该菌株所产的纤维素酶在中碱性条件具有较强的稳定性;K+、Fe2+、Mg2+对酶反应有促进作用,Hg2+、Cu2+对酶反应有抑制作用。     

Identification and optimal degradation conditions for cellulase-degrading enzyme of a methanol-utilizing and cellulase-producing bacterium

采用刚果红染色法,从废弃矿山周边土壤中筛选出一株产纤维素酶的甲醇利用细菌,命名为xt - 04.形态特征、生理试验及16S rDNA序列和gyrB序列分析表明,该菌株属于Bacillus methylotrophicus.为提高该菌所产纤维素酶的降解能力,首先通过单因子实验考察了底物CMC -Na浓度、反应温度及缓冲液pH值对纤维素酶活力的影响;然后采用响应面分析法对影响纤维素酶活力的3个单因子进行了优化.结果表明,单因素实验得出的适宜反应温度、缓冲液pH和底物浓度分别为70℃、5.0和2％ (20 mg/mL);响应面法得出的最高酶活力条件:反应温度、pH和底物浓度分别为66.1℃、4.81和19.01mg/mL.在最优条件下,酶活力达到17.85 U/mL,比优化前的酶活力12.84 U/mL提高了39.01％.因此,鉴于这种纤维素酶能耐受较高温度和酸性条件,该菌株所产纤维素酶可能在工业中具有良好的应用前景.     

爱尔兰帚霉产低温纤维素酶的酶学性质和发酵工艺

本文旨在对爱尔兰帚霉E71702M菌株产低温纤维素酶的酶学性质进行初步研究,并获得其最优发酵条件,为低温纤维素酶开发利用提供参考。通过单因素试验确定温度、pH及金属离子对纤维素酶活力的影响;以Plackett-Burman试验设计从8个培养条件中筛选出影响产酶的3个主要因素,即麸皮含量、装瓶量和起始pH;运用Box-Behnken试验设计及响应面分析法确定这3个主要因素的最优发酵条件。对酶学性质的初步研究表明,该酶最适pH为3.0,最适反应温度为30℃,在0℃时残余酶活力为最适反应温度时的56.3%。响应面分析得到最优发酵条件为:麸皮含量8.79g/L、装瓶量40.93m L、初始pH 4.01。通过优化,纤维素酶活力由0.6338IU/m L提高到1.7386IU/m L,提高了174%。     

Embryo and Endosperm Function and Failure inSolanumSpecies and Hybrids

Although the importance of the endosperm as a food store inmany angiosperm seeds is well known, its significance duringearly embryogenesis has been neglected. In many interspecifichybrids, and in some other situations, embryos do not developfully and abort. It has often been stated that this is causedby the endosperm failing to conduct sufficient nutrients tothe embryo, but seldom has it been suggested that the endospermactively controls most of the early stages of morphogenesisof the embryo. Information gleaned from a broad survey of theliterature, combined with additional evidence presented here,obtained fromSolanum incanumand interspecific hybrids, indicatethat the endosperm is dynamic and very active in regulatingearly embryo development. This requires highly integrated geneticcontrol of rapidly changing metabolism in the endosperm. Ininterspecific hybrids, lack of coordination may cause unbalancedproduction of growth regulating substances by the endospermand hence abortion of the embryo, or even unregulated productionof nucleases and proteases resulting firstly in autolysis ofthe endosperm and then digestion of the embryo. The endospermmay thus serve to detect inappropriate hybridization of speciesor ploidy levels and so prevent waste of resources by producingseeds that would result in sterile hybrids or unthrifty subsequentgenerations. This discriminatory function of the endosperm hasdiminished during evolution and domestication of the crop plantSolanummelongenaL.Copyright 1998 Annals of Botany Company Solanum, embryo morphogenesis, endosperm, hybrid, seed development.     

Pragmatic Women and Body Politics and Maternities and Modernities: Colonial and Postcolonial Experiences in Asia and the Pacific

Pragmatic Women and Body Politics. Margaret Lock and Patricia A. Kaufert. eds. Cambridge, UK: Cambridge University Press, 1998. xii +364 pp.
Maternities and Modernities: Colonial and Postcolonial Experiences in Asia and the Pacific. Kalpana Ram and Margaret Jolly. eds. Cambridge, UK: Cambridge University Press, 1998. xiv. 305 pp.     

HIFs and tumors--causes and consequences

For most organisms oxygen is essential fo life. When oxygen levels drop below those required to maintain the minimum physiological oxygen requirement of an organism or tissue it is termed hypoxia. To counter act possible deleterious effects of such a state, an immediate molecular response is initiated causing adaptation responses aimed at cell survival. This response is mediated by the hypoxia-inducible factor-1 (HIF-1), which is a heterodimer consisting of an alpha- and a beta-subunit. HIF-1 alpha protein is stabilized under hypoxic conditions and therefore confers selectivity to this response. Hypoxia is characteristic of tumors, mainly because of impaired blood supply resulting from abnormal growth. Over the past few years enormous progress has been made in the attempt to understand how the activation of the physiological response to hypoxia influences neoplastic growth. In this review some aspects of HIF-1 pathway activation in tumors and the consequences for pathophysiology and treatment of neoplasia are discussed.     

Morphological and constitutional features and self-esteem in children and adolescents

Studies of human constitution and mental features are traditionally among the main concepts of anthropological research. In this research, we attempted to discover connections between morphological and constitutional features and self-esteem in children and adolescents. Such a connection was discovered in some studied age groups. The obtained results could serve as a basis for further studies in this field.     

白蚁与动物及微生物的共生类型及其机制

综述了白蚁螱客的主要种类、共生关系及相关机制的研究进展。白蚁螱客中,已报道的动物种类达170种。在与动物的共生关系中存在偏利共生（宾主共栖和异种共栖）、互利共生和无关共生三种;在与微生物的共生关系中,存在与内生菌（原生动物、细菌、真菌和放线菌）和外生菌（蚁巢伞菌等）间的互利关系。指出了白蚁与螱客研究中存在的问题,给出了解决方案,并提出了今后可能的研究热点或方向,为白蚁的综合利用（如纤维素酶）及今后研究物种间的协同进化提供了基础资料。