B9601-Y2溶磷解钾固氮能力及促玉米生长效果研究

为了明确淀粉芽孢杆菌B9601-Y2(Y2)的促生长机制,通过摇瓶培养,检测其溶磷解钾固氮活性;通过盆栽试验,探索Y2对玉米生长量和溶磷解钾量的影响。结果表明,在第7天时,Y2固氮量为2.9 mg/L,解钾量为13.5μg/mL;在第4天时,溶磷量达732μg/mL。与空白对照相比,Y2发酵液能增加玉米株高28.29%,根长27.21%,叶宽18.56%,鲜重80.93%,干重66.67%;提高土壤中速效氮、速效磷和速效钾含量分别为20.42%、111.01%和17.24%,提高植株氮、磷、钾含量45.46%、120.17%、68.45%。研究结果表明,Y2活化土壤中难溶性磷、钾和具有固氮能力,并能促进植株对氮、磷、钾营养的吸收利用。     

芽孢杆菌几丁质酶基因的克隆、序列分析及其在伯克氏菌B418中的表达

采用PCR技术扩增到枯草芽孢杆菌几丁质酶基因的编码序列。片段共2227bp,含有一个具有1788个核苷酸的开放阅读框架,起始密码子位于211bp,终止密码子位于1998bp,共编码氨基酸605个。序列比较发现同已发表的枯草芽孢杆菌几丁质酶核苷酸具有99.39%的同源性。将该基因与大肠杆菌-伯克氏菌穿梭质粒pRK415连接,获得重组质粒pRChi113。重组质粒电击转入伯克氏菌B418中,获得工程菌株B418-9、B418-13。与野生菌株B418相比,平板拮抗试验表明,工程菌株B418-9、B418-13对大丽花轮枝孢、立枯丝核菌、麦根腐长蠕孢、禾谷丝核菌抑菌效果明显提高。     

水稻细菌性谷枯病菌的实时荧光PCR检测技术研究

 水稻细菌性谷枯病菌Burkholderia glumae于2007年被列为我国进境植物检疫性有害生物,国内急需建立针对该菌切实可行的检测技术, 以有效控制它在我国的传播。采用实时荧光PCR（real time fluorescence PCR）和经典PCR技术进行水稻细菌性谷枯病菌检测。研究结果表明,供试所有谷枯病菌都能产生139 bp左右的特异性片段,非谷枯菌株均无特异性片段产生。两种检测方法的灵敏度比较发现,常规PCR技术在病菌浓度为104CFU/mL时即可检测到,实时荧光PCR技术在病菌浓度为102CFU/mL时即可检测到,后者比前者的灵敏度高100倍。将模拟带菌种子与灭菌种子按1∶100混合,实时荧光PCR技术可以检测到该菌的存在。     

水稻根围和人体洋葱伯克氏菌的基因型比较

洋葱伯克氏菌是一组表型相似但基因型不同的细菌群（Burkholderia cepacia complex, 简称Bcc）,它存在于水稻生境和医院中,了解水稻根围Bcc菌株基因型的地位对水稻微生物安全性具有重要的意义。以recA基因的HaeⅢ RFLP技术和基因型特异性PCR扩增为主要方法对来自水稻根围的78株和来自医院的9株Bcc菌株进行了基因型分析。研究表明水稻根围存在Bcc菌株Ⅰ、ⅢB和Ⅴ基因型, 其中Ⅴ型为优势菌;而在医院来源的Bcc菌株中,存在Ⅰ、ⅢA和ⅢB型,以ⅢA型菌株最多。这表明我国水稻根围和医院中的洋葱伯克氏菌基因型构成存在差异。同时研究发现水稻根围的Bcc菌群具有明显的遗传多态性,且存在致病力强的Ⅲ型菌株。     

New Selective Medium for Isolation of Burkholderia glumae from Rice Seeds

A new selective medium for Burkholderia glumae was developed, which has a simpler composition and greater selectivity compared to Tsushima's S-PG medium currently used. This selective medium, designated CCNT, contains 2 g of yeast extract, 1 g of polypepton, 4 g of inositol, 10 mg of cetrimide, 10 mg of chloramphenicol, 1 mg of novobiocin, 100 mg of chlorotharonil and 18 g of agar in 1000 ml of distilled water, and is adjusted to pH 4.8. B. glumae produced a yellowish white colony with a diffusible yellow pigment on CCNT medium, which was distinguishable from other bacterial species when incubated at 41°C for 2 to 4 days. On CCNT medium, B. glumae was detected at a rate similar to that on S-PG medium in rice seeds, while other microorganisms were detected at a much lower rate. Received 16 September 1999/ Accepted in revised form 4 January 2000     

番茄立枯病菌拮抗菌B4-8的鉴定及生防作用评价

为了明确对番茄立枯病有生防效果的菌株B4-8的分类地位,并探索其生防作用机理和安全性,基于形态特征、生理生化特性及16S rDNA序列分析,对菌株B4-8进行鉴定;以平板对峙培养法测定其抑菌谱,并通过盆栽试验评价其对番茄立枯病的生防效果;采用生理生化和分子生物学的方法初步分析菌株的作用机制,并以洋葱和生菜叶中脉致病模型...     

Hitchhikers on the fungal highway: The helper effect for bacterial migration via fungal hyphae

Previous work in our laboratory showed that several bacterial strains, either singly or in association with other bacteria (community migration), were capable of migrating together with the saprotrophic fungus Lyophyllum sp. strain Karsten through soil microcosms. A possible involvement of the type III secretion system (TTSS) in migration was indicated. In this study, we addressed the basis of the community migration, which might lie in a migration helper effect exerted by particular single-strain migrators on other members of the community. Different culturing (plating) as well as culture-independent (PCR-DGGE) methods were applied to assess the effects of putative bacterial helpers in the migration. We used, as a model, the migration-proficient Burkholderia terrae BS001 as the canonical helper strain. PCR-DGGE analysis of the soil system with or without added strain BS001, revealed that the latter consistently stimulated the migration of different bacterial species through the soil. This was observed both following introduction of the organism to a bacterial community from soil and on the basis of a similar organism that was naturally present. One strain, Dyella japonica BS003, was identified as an avid comigrator with B. terrae BS001, although it appeared to lag behind the latter strain in its migration speed. Further examination of the B. terrae BS001/D. japonica BS003 interaction at Lyophyllum sp. strain Karsten hyphae showed that the presence of the D. japonica strain did not negatively affect the growth and migration of B. terrae BS001 with the fungus. A biofilm of B. terrae BS001 was formed on the fungal hyphal front, and we postulate a role for this biofilm in the migration helper effect.     

利用TaqMan探针实时荧光PCR方法检测香石竹细菌性萎蔫病菌

 根据香石竹细菌性萎蔫病菌基因组16S-23S rRNA保守序列,设计并合成了一对特异性引物和一条具有稳定点突变特异性探针,建立了对香石竹细菌性萎蔫病菌的TaqMan实时荧光PCR检测方法。除香石竹细菌性萎蔫病菌外,还对其他7种病原细菌菌株进行了荧光PCR检测。结果表明,只有香石竹细菌性萎蔫病菌产生荧光,其他病原细菌均没有荧光产生。与常规PCR相比,实时荧光PCR检测特异性强,灵敏度高,能检测到浓度为0.4 pg/μL的DNA,且能直接用于苗木等样品的检测,适合病害的快速诊断和口岸检验检疫应用。      

西双版纳红掌细菌性叶疫病病原菌初步研究

经鉴定,云南西双版纳的红掌细菌性叶疫病病原菌为Burkholderia caryophylli、Burkholderiasolanacearum、Pseudomonas sp.、Xanthomonas sp.等4个种。这4种菌的混合侵染力极强,目前在栽培管理上还缺乏有效的防治措施。