甜瓜采后病害生防菌遗传改良及其相关性状初步分析

X4(Pseudomonas fluorescens biovar Ⅲ)是利用直接生物测定的方法从甜瓜表面分离得到的生防菌株,此菌株并不产生抗生素2,4-DAPG,但对多种甜瓜采后病害具有较好生防能力。本试验利用Tn5转座子携带2,4-DAPG合成基因簇整合到X4上,得到改良菌株X4-G。经PCR检测和TLC检测导入成功,并且确定可在改良菌株X4-G中稳定存在。拮抗试验中,菌株X4和X4-G对甜瓜采后病害病原菌Fusarium spp.和Trichothecium roseum都有一定的抑制作用。菌株X4和工程菌株X4-G在甜瓜上对T. roseum生防效果均达到80%以上,且X4-G的防效优于X4。表明通过染色体整合抗生素2,4-DAPG合成基因可提高甜瓜采后病害生防菌株生防能力。     

木霉生防机制及应用的研究进展

摘要：木霉菌(Trichoderma spp.)是目前生防益菌中研究的热点,其生防机制假说呈现多元化。本文从竞争作用、重寄生作用、抗生作用、诱导抗性及协同拮抗作用五个方面综述了木霉菌的生防机制,并对其目前的应用现状进行了阐述。     

胡瓜钝绥螨控制大棚甜椒烟粉虱的研究

在我国山东省寿光市的蔬菜基地开展利用胡瓜钝绥螨控制日光大棚甜椒烟粉虱的研究.结果表明:(1)胡瓜钝绥螨能够捕食烟粉虱卵、成虫、若虫和伪蛹.在(25±1)℃、(30±1)℃、(35±1)℃下胡瓜钝绥螨以烟粉虱为猎物的发育历期与其取食柑橘全爪螨Panonychus citri(Mc Gregor)和二斑叶螨Tetranyc...     

应用假单胞菌防治植物真菌性病害研究进展

假单胞菌种类多、繁殖快,能通过产生多种抗生素及有效的根际定殖防治植物病害,促进植物生长,从而成为植物生防控制的重要研究对象。该文主要论述应用假单胞菌对植物真菌性病害进行生物防治的研究进展。     

陕西设施蔬菜根结线虫生防菌株JXC224的分离筛选

几丁质及蛋白质是构成根结线虫体壁和卵壳的主要物质。几丁质酶和蛋白酶活性的高低是评价生防真菌防治潜力的重要生化指标。从陕西省陕北关中陕南根结线虫病害严重的设施蔬菜大棚中采集土样、根结样106份,用分离培养基分离到真菌436株。液体发酵测定分离菌株的几丁质酶活及蛋白酶活,筛选获得几丁质酶活≥0.06 U/mL的菌株11株,蛋白酶活≥100 U/mL的菌株3株。其中JXC224几丁质酶活达0.087 U/mL,蛋白酶活125.8 U/mL,对根结线虫二龄幼虫的侵染率达67%,是一株具有开发潜力的生防菌株,经ITS测序分析,鉴定其为枝顶孢霉(Acremonium sp.)。     

拮抗酵母菌控制果蔬采后病害的研究进展

综述了拮抗酵母菌在果蔬采后病害防治上的应用及研究进展,包括拮抗酵母作为生防因子的作用机理和发展前景;指出了通过基因工程和生物工程技术的方法改造提高拮抗菌的生防效果是拮抗酵母菌作为生物防治的发展方向。     

解淀粉芽胞杆菌B1619生物摇瓶发酵工艺的正交优化

解淀粉芽胞杆菌Bacillus amyloliquefaciens B1619对设施蔬菜土传病害有较好的防治效果。为了提高菌株B1619生物发酵效率,本文通过单因子水平筛选和正交试验,对菌株B1619发酵培养基和培养条件进行了优化。结果表明,发酵培养基3个主要因子的最佳配比组合为酵母膏0.25%,大豆粉2.00%,生长素0.05%,优化后生物发酵效率比初始培养基提高了21.79%;发酵培养条件3个主要因子的最佳组合为温度28℃、转速180 r/min、装液量60 mL/250 mL,优化后生物发酵效率比初始培养条件提高了35.42%。经验证,优化后的生物发酵工艺获得的发酵菌液含菌量为7.13×10⁹cfu/mL,与初始发酵工艺的发酵菌液含菌量(3.80×10⁹ cfu/mL)相比,提高了87.83%,优化效率十分显著。     

Molecular Weight-Dependent Immunostimulative Activity of Low Molecular Weight Chitosan via Regulating NF-κB and AP-1 Signaling Pathways in RAW264.7 Macrophages

Chitosan and its derivatives such as low molecular weight chitosans (LMWCs) have been found to possess many important biological properties, such as antioxidant and antitumor effects. In our previous study, LMWCs were found to elicit a strong immunomodulatory response in macrophages dependent on molecular weight. Herein we further investigated the molecular weight-dependent immunostimulative activity of LMWCs and elucidated its mechanism of action on RAW264.7 macrophages. LMWCs (3 kDa and 50 kDa of molecular weight) could significantly enhance the mRNA expression levels of COX-2, IL-10 and MCP-1 in a molecular weight and concentration-dependent manner. The results suggested that LMWCs elicited a significant immunomodulatory response, which was dependent on the dose and the molecular weight. Regarding the possible molecular mechanism of action, LMWCs promoted the expression of the genes of key molecules in NF-κB and AP-1 pathways, including IKKβ, TRAF6 and JNK1, and induced the phosphorylation of protein IKBα in RAW264.7 macrophage. Moreover, LMWCs increased nuclear translocation of p65 and activation of activator protein-1 (AP-1, C-Jun and C-Fos) in a molecular weight-dependent manner. Taken together, our findings suggested that LMWCs exert immunostimulative activity via activation of NF-κB and AP-1 pathways in RAW264.7 macrophages in a molecular weight-dependent manner and that 3 kDa LMWC shows great potential as a novel agent for the treatment of immune suppression diseases and in future vaccines.