Partial Characterization of Chitinolytic Extract from Endophytic Streptomyces sp. and Its Effects on the Boll Weevil

The present study achieves the biochemistry partial characterization of the chitinolytic extract produced by an endophytic Streptomyces sp. strain （A8）. This extract was also tested against Anthonomus grandis, the cotton boll weevil aiming its control. The chitinase crude extract from the A8 strain was cultured for five days in a minimum liquid media supplemented with chitin. The extract was partially characterized by standard methods. The chitinolytic extract had an optimum temperature of 66 ＂C and an optimum pH between 4 to 9 （around 80% of relative activity）. We also characterized the temperature and pH stability and measured the effects of enzyme inhibitors. The filtered chitinolytic extract was added to an artificial boll weevil diet. Boll weevil development from the egg stage to the adult stage was prolonged, and the percentage of adults that emerged was approximately 66% less than on control diet. This study showed that the.larval development of A. grandis was inhibited by the presence of characterized chitinolytic extract in artificial diet. This work provides an experimental basis for using the chitinase from an endophytic bacterium Streptomyces sp. as a biocontrol alternativeto controlling the plant pest A. grandis.     

近10年来我国草原虫害生物防控综合配套技术的研究与推广进展

草原虫害防治是农业部较早大规模组织开展的防灾减灾工作之一。在长期的实践工作中,草原虫害防治始终坚持“预防为主,综合防治”的植保方针,逐步建立了“以生物防治为主,化学防治为辅”的技术路线。2002年起,全国畜牧总站在全国牧区组织开展了《草原虫害生物防控综合配套技术推广应用》项目。该项目的实施带动了全国的草原害虫防治,为草原可持续发展提供了技术支撑。本文以该项目的进展为基础,简要总结介绍了草原害虫防治的实施背景、开展情况及建设成果,包括以生态系统平衡原理为指导,对虫害监测预警、生物防控和施药技术等进行集成创新与组装配套,使草原害虫密度长期控制在经济阈值以下,实现草原生态系统平衡等。     

白桦木材变色生防菌的筛选研究

木材变色病原菌易引起木材变色,使木材发生降等。笔者采用从白桦原位土壤及自身组织分离纯化的方法,寻找对白桦变色病原菌具有拮抗作用的生防菌。经过改良5点对峙试验,筛选出对白桦木材变色5种病原菌具有拮抗作用的生防菌菌株共42株,其中x18及x26对5种病原菌都具有明显的拟制效果,菌落抑菌圈半径最大达2.1 cm。     

鲜枣采后生防菌株梅奇酵母XY201培养条件的优化

梅奇酵母（Metschnikowia zizyphicola）XY201是从冬枣表面分离筛选的新酵母菌种,对采后冬枣病原菌具有很好的抑制作用。本试验研究了该酵母菌对碳源、氮源和无机盐的利用情况,以及温度、初始pH和接种浓度三个因素对梅奇酵母生物量的影响,优化其培养基配方和培养条件。结果表明,梅奇酵母最大生物量的培养基配方为：2%蔗糖＋2%牛肉蛋白胨＋0.05%磷酸二氢钾＋0.05%硝酸钠;最优培养条件为：培养温度25℃,初始pH 6.0,接种浓度1%;在上述培养条件下进行摇瓶培养,梅奇酵母的最佳培养时间为接种后72 h。     

番茄青枯病生防芽胞杆菌的筛选与鉴定

为了有效利用芽胞杆菌资源,本研究采用抑菌圈法从不同地理来源的芽胞杆菌中筛选出24个对青枯雷尔氏菌具有拮抗作用的菌株。其中,6个菌株对青枯雷尔氏菌的抑菌圈直径大于14.00 mm,菌株FJAT-11709的抑菌圈直径最大,为14.78 mm。盆栽试验比较了6个菌株对番茄青枯病的防治效果,结果表明,菌株FJAT-20261和FJAT-19700防效最好,分别达72.73%和67.77%。通过形态特征、生理生化测定及16S rRNA基因序列分析,菌株FJAT-20261和FJAT-19700分别被鉴定为耐寒短杆芽胞杆菌和特基拉芽胞杆菌。本文报道这2种芽胞杆菌对青枯雷尔氏菌具有拮抗作用,为青枯病的生物防治提供了新的菌株资源。     

植物内生真菌作为生防因子的研究进展

本文对内生真菌作为生防因子的研究进展进行了综述,主要包括内生真菌在植物抗病性、抗虫性、抗逆性等方面的研究情况及其在生产中应用存在的问题.     

Use of the Genetically Engineered Agrobacterium Strain K1026 for Biological Control of Crown Gall

Strain K84 of Agrobacterium (formerly called A. radiobacter) has been a successful biocontrol agent of crown gall disease for almost 30 years all over the world. In spite of its demonstrated efficiency, the most important risk of failure when using strain K84 is the possibility of transfer of plasmid pAgK84 to pathogenic Agrobacterium strains. pAgK84 codifies production of and immunity to agrocin 84, the main factor involved in crown gall biocontrol by strain K84. Then, a second generation of strain K84 was obtained and the genetically engineered strain was called K1026. It contains a deletion in the transfer region of pAgK84. To date, a considerable number of studies have been performed to compare both strains in its ability to control crown gall, plasmid transfer, antibiotic production, root colonization and survival in the rhizosphere. The aim of this review is to discuss all this comparative available information which advises that strain K1026 should be used as a biopesticide to safeguard biocontrol of crown gall wherever strain K84 is employed.     

烟草青枯病内生拮抗菌的筛选、鉴定及其防效测定

 植物体内的大量微生物,在进化的过程中,由于长期生活在植物特定部位,因而与植物形成了一种特殊的关系,这些微生物在植物体内大量繁殖和扩散,有望成为生物防治有潜力的微生物。内生细菌是植物体内大量存在的微生物之一,具有在植株体内分布广、定殖能力强、防效好以及增殖和扩散快等优点,因而成为发展前景很好的植物病害生防菌。     

寡雄腐霉发酵参数优化及发酵液的生防效应

【目的】优化寡雄腐霉（Pythium oligandrum）发酵条件,为烟草黑胫病的生物防治奠定基础。【方法】采用单因素和正交试验研究寡雄腐霉的发酵参数及优化组合,并利用烟草黑胫病菌（Phytophthora nicotiana）、离体烟叶和盆栽烟苗验证发酵液的生防效应。【结果】随培养时间的延长,寡雄腐霉菌丝生物量持续增加,但发酵液对烟草黑胫病菌的抑制作用增加至峰值后降低。在不同培养基、温度、pH值和光照等条件下,寡雄腐霉的生物量越大,发酵液对烟草黑胫病菌的抑制作用愈强,二者的相关系数r =0.77**（n=16）。以黄豆饼粉为培养原料,初始pH值6.0、培养温度30℃、持续光照培养6 d所得的寡雄腐霉菌丝生物量最高,其发酵液对烟草黑胫病菌抑制率分别达到78.8%（菌丝生长）和52.9%（孢子萌发）。此外,寡雄腐霉发酵液显著降低离体烟叶和盆栽烟苗黑胫病的发病率和病情指数,对离体烟叶黑胫病的防效为69.3%—75.3%;对盆栽烟苗黑胫病的防效为55.0%—61.3%。【结论】在寡雄腐霉发酵过程中,选用适宜的培养基、pH值、温度、光照和发酵时间组合,可使发酵液抑制烟草黑胫病的效果达到最佳。