苏云金芽孢杆菌几丁质酶的研究进展

苏云金芽孢杆菌制剂作为无公害农药已经得到社会的认可,如果再开发其几丁质酶抑制真菌和杀虫增效功能,不仅可充分利用这一农业微生物菌种资源,也将给予传统生物农药以新的生命力。综述了苏云金芽孢杆菌几丁质酶方面研究的国内外最新进展。     

苏云金芽孢杆菌蛋白酶发酵动力学模型的构建

对苏云金芽孢杆菌FS140蛋白酶分枇发酵的代谢特性进行了研究.首先描述了FS140分枇发酵过程中细胞生长、产物积累、糖消耗的变化规律.基于Logistic方程和Luedeking-Piret方程,建立了苏云金芽孢杆菌蛋白酶发酵过程细胞生长、产物合成及基质消耗随时间变化的数学模型.动力学模型计算值结果与实验值拟合良好,较好反映了苏云金芽孢杆菌分批发酵过程的动力学特征.     

苏云金芽孢杆菌Ⅱ类转座因子的应用与研究进展

苏云金杆菌的转座因子分为两类：Ⅰ类,插入序列;Ⅱ类,转座子．在结构上,这些转座因子与苏云金芽孢杆菌杀虫晶体蛋白（ICPs）基因相联系,并且这些具有转座活性的转座因子在ICPs基因的转移和变异上起着重要作用．对苏云金芽孢杆菌的Ⅱ类转座因子即转座子的结构、作用机制、应用与研究进展进行了综述．     

单宁对苏云金芽孢杆菌库斯塔克变种杀棉铃虫效力的作用(英文)

本文报道棉铃虫、苏云金芽孢杆菌库斯塔克变种和单宁三者间的相互作用。苏云金芽孢杆菌芽孢晶体混合粉以6个不同的浓度（0％,0．005％,0．01％,0．015％,0．02％,0．025％湿重）分别加入含0．025％单宁和不含单宁的人工饲料中。初孵幼虫分别在上述饲料中饲养48h后,转入相应的不含苏云金芽孢杆菌的人工饲料上饲养,直到留存的幼虫化蛹。结果表明,单宁与苏云金芽孢杆菌混用可提高苏云金芽孢杆菌对棉铃虫的毒力,LD50降低45％,并可显著抑制该虫的生长发育,但二者在抑制生长发育方面无交互作用。选择取食试验显示,苏云金芽孢杆菌对五龄幼虫有显著的抑食性,但单宁无此作用,单宁与苏云金芽孢杆菌混用不会增强抑食性,但单宁能抑制苏云金芽孢杆菌菌落的生长,浓度高于15mg／100ml还能抑制芽孢的萌发。     

苏云金芽孢杆菌芽孢萌发相关基因gerM的克隆及功能研究

依照蜡状芽孢杆菌gerM基因的保守序列设计引物,从苏云金芽孢杆菌中扩增出640bp的DNA片段。以此为探针,从苏云金芽孢杆菌部分基因组酶切文库中成功地克隆到了一个4·5kb的DNA片段。序列分析表明,该片段包含一个完整的开放阅读框,其预测的编码产物与枯草芽孢杆菌GerM蛋白具有很高的同源性,将该基因命名为gerM。RT-PCR分析表明,gerM基因仅在芽孢形成的过程中表达。通过同源重组的策略构建了gerM基因的阻断突变株。研究表明,gerM基因的破坏影响苏云金芽孢杆菌芽孢萌发的速率和比例。     

恒定磁场对苏云金芽孢杆菌的生长及毒力的影响

目的:研究恒定磁场对苏云金芽孢杆菌的生长和毒力的影响.方法:通过0-100 Gs的恒定磁场下对苏云金芽孢杆菌G-02、HD-1菌株的发酵,测定其生长和毒力的变化.结果:G-02、HD-1菌株分别在磁场强度43Gs和14Gs条件下发酵48h后的芽孢量和毒力达到最高,芽孢增长比分别为1.26和2.0,毒力增效比分别为1.27和1.25,苏云金芽孢杆菌G-02适宜的磁场强度为43-50Gs,HD-1菌株为7-29Gs.结论:低磁场强度对两种菌株的生长有一定的促进作用,而高强度磁场会对其生长产生抑制作用.     

苏云金芽孢杆菌转座因子研究进展

近年来的研究发现苏云金芽孢杆菌转座因子和许多毒力因子可能是紧密联系的。由于转座因子的特殊性质,使它们在现代农业生物技术中有着广泛的应用前景,科学家对苏云金芽孢杆菌转座因子的研究也在不断深入。本文主要针对苏云金芽孢杆菌转座因子的研究进展进行综述,并对发展前景进行展望。     

我国森林土壤中苏云金芽孢杆菌生态分布的研究

从我国8个森林立地带(寒温带、中温带、暖温带、北亚热带、中亚热带、南亚热带、高原亚热带、热带)所属的13个自然保护区,采集了0—5cm土层林下土壤样品384个.测定了土壤pH、水分和养分.从中分离观察芽孢杆菌菌落1873个,分离出苏云金芽孢杆菌79株,并对其所属亚种进行了初步鉴定.其平均出土率和分离率分别为14.32%和4.21%.研究了芽孢杆菌和苏云金芽孢杆菌在森林土壤中生态分布的规律及苏云金芽孢杆菌对6种昆虫的室内毒力测定,从中筛选出不少的高效菌株.为研究苏云金芽孢杆菌在我国森林生态系中资源的保护、开发和利用,具有重要意义.     

从湖北神农架原始森林土壤中分离的高毒力苏云金芽孢杆菌

从神农架原始森林土壤中分离出苏云金芽孢杆菌 9株。经过生理生化和血清学鉴定 ,此 9株苏云金芽孢杆菌分属于H7、H6和H14。生物测定结果表明 :两株H7型菌株对棉铃虫幼虫有较高的毒力 ;另两株对致倦库蚊幼虫和白纹伊蚊幼虫有很强的毒杀作用 ,此两株属苏云金芽孢杆菌H14。     

苏云金芽孢杆菌双组份信号转导系统的生物信息学分析

苏云金芽孢杆菌(Bacillus thuringiensis)能产生杀虫晶体蛋白等多种活性成分,是目前应用最广泛的微生物杀虫剂。本文采用生物信息学方法,系统分析了由本实验室完成全基因组测序的苏云金芽孢杆菌YBT-1520、CT-43和BMB171 3个菌株的双组分信号转导系统(Two-componentsignal transduction system,TCS)的分布、结构及功能,并初步构建了部分TCS的调控网络关系图。本研究旨在为深入研究苏云金芽孢杆菌的生长、代谢以及毒力因子的表达与调控,全面了解伴孢晶体的形成机制开辟新的研究方向。     

不同添加物对苏云金芽孢杆菌杀虫活性的增效作用研究进展

苏云金芽孢杆菌（Bacillius thuringiensis,Bt）制剂是当前应用最广、最有效的生物杀虫剂之一,因其对多种昆虫具有特异性杀虫活性,而被广泛用于农林业和公共卫生等领域的害虫防治,但田间施用后,其速效性差、持效期短和防效不稳定等弊端限制了其进一步的推广。将Bt制剂与增效物质（剂）、因子混合使用以提高其杀虫活性和田间防效稳定性,是最快速、有效的途径之一,因而国内外对此开展了广泛而深入的研究。主要介绍了化学添加剂、化学杀虫剂和生物杀虫剂等添加物对Bt制剂杀虫活性的增效作用研究进展,并探讨了增效物质（剂）、因子的开发和应用前景,以期为开发安全、高效的Bt制剂的增效物质（剂）、因子提供一定的参考。     

Acute, sublethal and combination effects of azadirachtin and Bacillus thuringiensis toxins on Helicoverpa armigera (Lepidoptera: Noctuidae) larvae

The efficacy of neem (1500 ppm azadirachtin (AI)), Delfin WG, a biological insecticide based on selected strain of Bacillus thuringiensis Berliner (Bt) subspecies kurstaki, and Cry1Ac protein, either individually or in combination, were examined against first to fourth instar Helicoverpa armigera (Hübner) larvae. Using an oral administration method, various growth inhibitory concentrations (EC) and lethal concentrations (LC) were determined for each bioagent. Combinations of sublethal concentrations of Bt spray formulation with azadirachtin at EC50 or EC95 levels not only enhanced the toxicity, but also reduced the duration of action when used in a mixture. The LC20 and LC50 values for Cry1Ac toxin were 0.06 and 0.22 microg ml-1, respectively. Bt-azadirachtin combinations of LC50+EC20 and LC50+EC50 result in 100% mortality. The mortality also was significant in LC20+EC20 and LC20+EC50 mixtures. These studies imply that the combined action is not synergistic but complimentary, with azadirachtin particularly facilitating the action of Bt. The Bt spray-azadirachtin combination is more economical than combinations that involve isolating the toxic protein, as the Bt spray formulations can be combined in a spray mixture with neem. These combinations may be useful for controlling bollworm populations that have acquired resistance to Bt as they may not survive the effect of mixture. Azadirachtin may be useful as a means of reducing the endotoxin concentrations in a mixture, to promote increased economic savings and further reduce the probability of resistance development to either insect control agent.     

蛋白改造提高苏云金杆菌杀虫活力的研究进展

苏云金杆菌(Bt)已被广泛应用于农林害虫防治,但传统制剂仍然存在很大局限性,利用蛋白质工程对其改造能有效的克服这些缺点.主要概述了近年来利用结构域转换和定点突变技术改造Bt Cry蛋白并增强其杀虫活性的研究进展.     

Effect of Bacillus thuringiensis and a pyrethroid insecticide on the leaf microflora of Brassica oleracea

In a field experiment comparing the effect of treatment with Bacillus thuringiensis (Bt) and the pyrethroid insecticide, cypermethrin, on leaf microflora across the growing season, no significant differences were found, apart from more bacteria on cypermethrin-treated leaves on 24 September ( P < 0·05). No effect was seen on fungal diversity or numbers. In contrast, the pyrethroid insecticide inhibited growth of 44% of bacterial isolates tested in vitro; Bt was not inhibitory. Bacillus thuringiensis numbers on treated leaves increased throughout the season, following repeated applications.     

粘虫颗粒体病毒与苏云金杆菌联合作用对甜菜夜蛾的影响

以甜菜夜蛾为试虫,测定了粘虫颗粒体病毒（PuGV-Ps）对苏云金杆菌（Bt）毒力的增效作用。结果表明PuGV对甜菜夜蛾没有致毒作用,但Bt中加入PuGV后可以提高Bt对甜菜夜蛾的毒力,甜菜夜蛾致死中量LC50由Bt单剂的1．094mg／mL下降到0．862mg／mL,共毒系数达127。亚致死剂量Bt处理甜菜夜蛾影响了幼虫的生长发育,表现为幼虫生长量相对减少、蛹重下降、化蛹率降低和化蛹历期延长,添加了PuGV-Ps后进一步增强了Bt对甜菜夜蛾的生长发育的抑制作用。甜菜夜蛾中肠蛋白酶活性测定结果表明,PuGV-Ps对甜菜夜蛾中肠酶活性具有抑制作用;昆虫同时取食PuGV-Ps和Bt后,中肠酶液总蛋白酶活力都有所下降,在中肠酶液最适pH范围内蛋白酶活力抑制作用最明显。     

Bacillus spp. toxicity against Haemonchus contortus larvae in sheep fecal cultures

The gastrointestinal nematode Haemonchus contortus is a major productivity constraint in sheep. In this study, the nematicidal effects of Bacillus circulans, Bacillus cereus, Bacillus thuringiensis var. israelensis, Bt. var. osvaldocruzi, Bt. var. morrisoni, and Bt. var. kurstaki were assessed in free-living larval stages of H. contortus. A spore-crystal suspension containing approximately 2×10(8)UFC/mL of each strain was added to sheep feces that were naturally infected with H. contortus eggs, and the presence of larvae was then evaluated. We observed a significant (p>0.05) reduction in larval development when using B. circulans, B. thuringiensis var. israelensis, Bt. var. osvaldocruzi and Bt. var. kurstaki, and these effects were proportional with the amount of bacteria added to the feces. However, no effect was observed when Bt. var. morrisoni or B. cereus was added. These observations suggest that these bacteria might be effective as nematicides and may allow for the development of integrated biological control of zooparasitic nematodes.     

我国苏云金杆菌研究60年

综述了我国近60年来的苏云金杆菌研究进展,包括资源收集及分类鉴定、Bt新基因的发掘及组学研究、病理学与作用机制、毒力测定、产品标准化、产业化,并就Bt生物农药存在的问题及改善途径进行了探讨。     

Bt棉花害虫综合治理研究前沿

自1996年以来,全球Bt(Bacillus thuringiensis)棉花应用规模迅速增长,目前已占棉花种植总面积的60%左右,主要种植国家包括美国、澳大利亚、中国、印度和巴基斯坦等。大量研究表明,Bt棉花的大面积种植有效控制了多种靶标害虫的发生危害,从而大幅度减少了化学杀虫剂的使用量;化学杀虫剂的减少使用导致一些非靶标害虫的发生危害明显加重。针对Bt棉花生产中呈现出的害虫新问题,各国分别发展了由农业防治、生物防治、化学防治等不同措施构成的防控技术体系。     

Effect of bacterial infection on antioxidant activity and lipid peroxidation in the midgut of Galleria mellonella L. larvae (Lepidoptera, Pyralidae)

Bacillus thuringiensis is one of the most widely used sources of biorational pesticides, as well as a key source of genes for transgenic expression to provide pest resistance in plants. In this study the effect of Bacillus thuringiensis ssp. galleriae (Bt) infection on the activity of superoxide dismutase (SOD), glutathione S-transferase (GST), catalase (CAT), concentrations of oxidated and reduced thiols (RSSR/RSH) and malondialdehyde (MDA) was tested in the midgut of Galleria mellonella larvae. We found that Bt infection resulted in increased activities of SOD, GST, malondialdehyde and RSSR/RSH ratio the first day after inoculation. However, catalase activity decreased on the first and following days after bacterial infection by Bt. Our results confirm the hypothesis that Bt infection increases the level of oxidative stress in the larval midgut. In light of this study, it seems possible that oxidative damage contributes to cell death in the midgut during bacteriosis.