新型杀虫晶体蛋白Cry7Ab4空间结构的计算机解析

采用一级结构分析,二级结构预测及同源比对建模的方法,模拟出新型杀虫晶体蛋白Cry7Ab4的空间结构,并进行动力学优化.结合其杀大猿叶甲活性数据与蛋白结构比对分析,发现Cry7Ab4与Cry7Aa1的活性差异主要归因于α3,α4上疏水性氨基酸的不同.     

芽孢杆菌对肉仔鸡蛋白质代谢的影响

以旧龄艾维菌肉仔鸡饲喂不同水平芽孢杆菌制剂，通过对血清总蛋白(TP)和非蛋白氮(NPN)以及肝脏RNA／DNA值进行测定分析，结果表明：芽孢杆菌制剂对促进肉仔鸡蛋白质合成具有积极作用。     

哈茨木霉菌与蜡样芽孢杆菌复合使用对田间番茄根结线虫的生防效果测定

通过单一及复合使用哈茨木霉菌与蜡样芽孢杆菌,调查不同处理对大田番茄根结线虫的预防和防治效果。田间试验结果表明,连续施用两次生防菌后,两种微生物菌剂的复合使用比单一菌株对根结线虫表现出明显的预防和防治效果。45 d后两种微生物菌剂复合使用对番茄根结线虫的预防和防治效果分别达到70.2%、48.4%,根际土壤根结线虫减退率分别达到61.4%、54.9%,番茄根中根结线虫减退率分别达到75.9%、60.7%,显著高于单一菌株对根结线虫的预防和防治效果（P<0.05）,研究结果为下一步研发微生物菌剂的复合使用防治番茄根结线虫提供了参考依据。     

解淀粉芽孢杆菌GSBa-1凝乳酶对羊奶干酪成熟特性的影响

为探究解淀粉芽孢杆菌GSBa-1凝乳酶制备的羊奶干酪(干酪B)成熟特性的变化,以采用商业凝乳酶和同批次羊奶制作的干酪(干酪A)为对照组,比较两组干酪在60d成熟期主要组分、质构特性、微生物指标及风味物质的变化。结果表明,两组干酪得率相差不大。成熟期间干酪的水分、蛋白质及脂肪含量呈先上升后下降趋势,干酪B始终高于干酪A;干酪游离氨基酸总量在成熟期间呈先下降后上升趋势,且干酪B中苯丙氨酸、天冬氨酸、异亮氨酸、甲硫氨酸、丝氨酸含量高于干酪A。成熟前期干酪B质构特性优于干酪A。干酪A成熟后乳酸乳球菌数量增加了(5.22±0.02)%,干酪B无显著变化(P>0.05)。成熟期内,两组干酪中挥发性风味物质种类和含量均增加,但干酪B中的壬酸、辛醇、2-庚酮、2-壬酮、二甲基砜使羊奶干酪风味独特、浓郁。因此,GSBa-1凝乳酶具备替代商业凝乳酶用于羊奶干酪生产的潜力,可对干酪风味的形成和品质的提升起到一定促进作用。     

Assembly and genetics of spore protective structures

The sporulation program in Bacillus subtilis ends in the formation of a highly resistant endospore that can withstand extremes of heat, mechanical disruption, ultraviolet irradiation, lytic enzymes and chemical attack. These properties are attributed mainly to the unique structure of spore coat and cortex, as well as to the physical state of the spore cytoplasm. The outermost layer of the spore, called the coat, has two morphologically distinct sublayers: an electron-dense outer coat and an electron-translucent inner coat. The coat is composed of more than 2 dozen proteins of varying size. Many coat genes and coat proteins have been isolated and characterized in detail, and studies of these have identified proteins with important roles in coat assembly, resistance and spore germination. We describe here characteristics of the coat proteins and propose a model for coat assembly based on recent work.     

水解胶原蛋白对枯草芽胞杆菌生长的影响

本文测定了不同氮源(水解胶原蛋白CH、蛋白胨、明胶、硝酸钠、氯化铵)对枯草芽胞杆菌(Bacillus subtilis)生长的影响;考察了CH和玉米浆的不同配比对枯草芽胞杆菌生长的影响;研究以CH为氮源时,不同碳源对枯草芽胞杆菌生长的影响;考查CH对其它细菌发酵的影响.研究发现,在CH为氮源条件下,枯草芽胞杆菌的发酵过程可顺利进行,且微生物的生物量可保持在较高水平;同玉米浆相比,CH能使枯草芽胞杆菌达到较高的生物量;以CH为氮源时,淀粉比葡萄糖、蔗糖更有利于枯草芽胞杆菌的生长;除了枯草芽胞杆菌以外,大肠杆菌(Escherichia coli ATCC 15489)和地衣芽胞杆菌(Bacillus licheniformis CICC 20031)也能有效利用CH.这表明,在实验条件下水解胶原蛋白(CH)可以作为多种微生物发酵的氮源.     

苏芸金杆菌代谢特性研究

采用12L玻璃发酵罐,测定了苏芸金杆菌(Bacillus thuringiensis, B. t)发酵过程中的菌体浓度、总糖、还原糖、氨基氮、溶磷、溶氧、铵离子、核酸、ATP、pH、蛋白酶及粘度等参数。获得了B.t生长过程的代谢曲线,从中分析了各参数变化间的相互关系。这对于控制B.t发酵过程及提高发酵水平具有一定指导意义。     

Keratinase production and keratin degradation by a mutant strain of Bacillus subtilis

A new feather-degrading bacterium was isolated from a local feather waste site and identified as Bacillus subtilis based on morphological, physiochemical, and phylogenetic characteristics. Screening for mutants with elevated keratinolytic activity using N-methyl-N＇-nitro-N-nitrosoguanidine mutagenesis resulted in a mutant strain KD-N2 producing keratinolytic activity about 2.5 times that of the wild-type strain. The mutant strain produced inducible keratinase in different substrates of feathers, hair, wool and silk under submerged cultivation. Scanning electron microscopy studies showed the degradation of feathers, hair and silk by the keratinase. The optimal conditions for keratinase production include initial pH of 7.5, inoculum size of 2% （v/v）, age of inoculum of 16 h, and cultivation at 23 ℃. The maximum keratinolytic activity of KD-N2 was achieved after 30 h. Essential amino acids like threonine, valine, methionine as well as ammonia were produced when feathers were used as substrates. Strain KD-N2, therefore, shows great promise of finding potential applications in keratin hydrolysis and keratinase production.     

SD－5菌株原生质体形成与再生条件的研究

探讨了培养基成分、培养时间、高渗缓冲液成分和ｐＨ、溶菌酶浓度以及酶解温度和时间对苏云金杆菌ＳＤ—５菌株原生质体形成和再生的影响；结果表明，ＳＤ—５菌株原生质体形成和再生的最佳条件组合为：ＰＢＧ培养基、３０℃培养１４ｈ再活化５ｈ，以ＳＭＭｐＨ６．５作酶解缓冲液，溶菌酶浓度０．６ｍｇ／ｍｌ，３４℃处理６０ｍｉｎ．