黑木相思根瘤菌遗传多样性

[目的]研究分离自广东、福建、江西等15个地点的174株黑木相思(Acacia melanoxylon)根瘤菌的遗传多样性.[方法]采用16S rDNA限制性片段长度多态性分析(Restriction fragment length polymorphism,RFLP)和16S rDNA基因、持家基因(recA、atpD、glnⅡ)系统发育分析的方进行研究.[结果]16S rDNAPCR-RFLP分析中,在70％的相似性水平上,所有供试菌株分成9个类群 ;16S rDNA基因和持家基因系统发育分析结果基本一致,34株代表菌株主要分布在α-变形菌纲(Alpha-Proteobacteria)的慢生根瘤菌属(Bradyrhizobium)、根瘤菌属(Rizobium)、中慢生根瘤菌属(Mesorhizobium),并与Bradyrhizobium liaoningense、Bradyrhizobium betae、Bradyrhizobium cytisi、Rizobium multihospitium、Mesorhizobium plurifarium亲缘关系较近.[结论]供试菌株被鉴定到属的水平,Bradyrhizobium、Rhizobium或Mesorhizobium为优势菌群,证明了黑木相思根瘤菌具有丰富的遗传多样性.     

江汉平原及其周边地区花生根瘤菌的遗传多样性

采用RAPD分析技术和16S－23S rRNA间隔区段（IGS）RFLP分析,分别对分离自江汉平原及其周缘地区的花生根瘤菌进行了遗传多样性和系统发育研究。结果表明,全部供试验菌分别在48％和50％的相似性水平分为Ⅰ、Ⅱ两群,供试花生根瘤菌与参比菌株B.japonicum和B.elkanii聚在群I,参比菌株Rhizobium Sinorhizobium,Mesorhizobium和Agrobacterium聚在群Ⅱ。供试花生根瘤菌的遗传多样性及其在系统发育中的地位主要受地域因素的影响,来自江汉平原中心地带天门和潜江的菌株在76％以上的相似性水平上聚在一起,处于周边地带的武汉和荆州,由于其特定的地理因素的影响。菌株的多样性更为丰富,部分菌株在分类上与其它地域的菌株相互融合,并在较高的相似水平存在一定摆动性,来自外缘随州的菌株,表现了明显的地理分隔作用,其在系统演化中的地位相对独立,总体上从平原腹地到外缘地区。根瘤菌地理分隔作用逐渐明显,在平原外缘的交接地带,根瘤菌的多样性最为丰富。     

攀枝花市银合欢根瘤菌遗传多样性

【目的】研究分离自四川攀枝花的银合欢根瘤菌的遗传多样性。【方法】采用联合16S rDNA RFLP和IGS RFLP的综合聚类分析(16S-IGS RFLP)、AFLP及多位点持家基因(16S rDNA,atpD,recA)序列的联合分析对供试银合欢根瘤菌进行研究。【结果】31株未知菌具有15种16S-IGS遗传图谱类型、27种AFLP类型。16S-IGS RFLP结果表明,没有未知菌与Bradyrhizobium的参比菌株聚在一起。在71.4%的相似水平上,31个未知菌按属的水平分成3个分支:S、M和R,分别分布在Sinorhizobium属(28株)、Mesorhizobium属(2株)和Rhizobium属(1株)。S分支的28个菌在84%的相似水平上,16S-IGS RFLP聚类图中构成3个群:群S1、群S2、群S3;在AFLP聚类图中构成9个AFLP群:S1–S9。多位点基因序列表明,代表菌株SCAU215、SCAU231分别与M.Plurifarium、R.huautlense亲缘关系最近。而分布于Sinorhizobium属SCAU222和SCAU228、SCAU213、SCAU216可能代表Sinorhizobium的3个新类群。【结论】攀枝花市银合欢根瘤菌遗传多样性丰富,分布于Sinorhizobium、Mesorhizobium和Rhizobium三个属,且优势类群为Sinorhizobium。     

我国南北大豆产区慢生大豆根瘤菌的遗传多样性和系统发育研究

利用16S rRNA基因RFLP、16S rRNA基因序列分析以及16S-23S rRNA IGS PCR RFLP技术对分离自我国南北大豆产区的慢生大豆根瘤菌进行了群体遗传多样性和系统发育研究。16S rRNA基因PCR RFLP分析以及16S rRNA基因序列分析结果表明:所有供试慢生大豆根瘤菌可分为B.japonicum和B.elkanii两个类群,其中属于B.japonicum的为优势种群,占供试菌株的91%,属于B.elkanii的仅占9%,多样性水平较低。16S-23S rRNA IGS PCRRFLP研究结果表明:属于B.japonicum的慢生根瘤菌具有较丰富的遗传多样性,在69%的相似性水平上可分为群Ⅰ和群Ⅱ两大类群。群I的菌株以分离自黑龙江和河北等北部区域的菌株为代表,群Ⅱ的菌株以分离自广西和江苏等南部地域的菌株为代表,反映出明显的地域特征。两群菌株在系统发育上均与USDA6、USDA110和USDA122等B.japonicum的模式或代表菌株有差异。     

黄土高原地区大豆根瘤菌的遗传多样性和系统发育

【目的】研究黄土高原地区大豆根瘤菌的遗传多样性和系统发育。【方法】采用BOX-PCR、16S rDNAPCR-RFLP、16S-23S IGS PCR-RFLP和16S rRNA基因序列分析方法对分离自我国黄土高原地区4个省的15个地区的130株大豆根瘤菌及部分参比菌株进行了遗传多样性和系统发育分析。【结果】BOX-PCR反映的菌株多样性最丰富,形成的遗传群最多,16S rDNA PCR-RFLP方法在属、种水平上聚群较好,16S-23S IGSPCR RFLP反映的多样性介于BOX-PCR和16S rDNA PCR-RFLP之间,能够较好地反映出属、种和亲缘关系很近的菌株间的差异,3种方法聚类分析结果基本一致,可将所有供试菌株分为两大类群,中华根瘤菌属(Sinorhizobium)和慢生根瘤菌属(Bradyrhizobium)。从系统发育来看,供试的快生大豆根瘤菌为费氏中华根瘤菌(Sinorhizobium fredii),慢生大豆根瘤菌为日本慢生大豆根瘤菌(Bradyrhizobium japonicum)和辽宁慢生根瘤菌(Bradyrhizobium liaoningense)。【结论】我国黄土高原地区大豆根瘤菌具有较丰富的遗传多样性,S.fredii优势种,慢生大豆根瘤菌仅占10%,同时,分离到2株B.liaoningense。     

神木地区耐旱灌木和草本豆科植物根瘤菌遗传多样性

豆科植物具有抗逆性强、耐瘠薄的特性,许多豆科植物是荒漠地区的先锋植物,在生态环境保护中起重要作用.以神木地区主要的灌木和草本豆科植物-根瘤菌共生体系为材料,采用16S rRNA PCR-RFLP和序列分析等方法,对分离得到的55株菌进行多样性分析,其中,30株菌分离自灌木豆科植物紫穗槐和柠条,25株菌分离自草本豆科植物斜茎黄芪、苜蓿、草木樨黄芪等.结果表明: 这些菌株共有11种16S rRNA PCR-RFLP遗传图谱类型,分离自草本豆科植物的菌株主要归属于中慢生根瘤菌属、剑菌属、根瘤菌属、叶瘤杆菌属和土壤杆菌属5个属,分别与华癸中慢生根瘤菌、地中海中慢生根瘤菌、刺槐中慢生根瘤菌、费氏剑菌、草木樨剑菌、木兰根瘤菌、放射根瘤菌、突尼斯叶杆菌和根癌土壤杆菌系统发育关系最近.分离自灌木豆科植物的菌株仅归属于中慢生根瘤菌属,分别与华癸中慢生根瘤菌和地中海中慢生根瘤菌系统发育关系最近.华癸中慢生根瘤菌和地中海中慢生根瘤菌是两类豆科植物的共生菌种,表明在干旱地区,根瘤菌对两种类型豆科植物的选择共生存在差异,这与豆科植物种类有关,还可能与其所处生态环境有关.     

凉山州新银合欢根瘤菌的共生有效性及遗传多样性

【目的】研究分离自四川凉山州新银合欢根瘤菌的遗传多样性和共生有效性。【方法】采用16S rRNA RFLP、BOX-PCR、AFLP、多位点持家基因序列的联合分析及无氮水培法对33株供试新银合欢根瘤菌的遗传多样性和共生有效性进行研究。【结果】分析表明,3种方法在属水平的分群结果具有较好的一致性,有1个Mesorhizobium属的菌株、3个Bradyrhizobium属的菌株、3个Rhizobium属的菌株,26个相似度较高的菌株属Sinorhizobium。16S rRNA-recA-atpD-glnII序列联合构建的新银合欢根瘤菌系统发育树表明,SCAU203、SCAU211可能分别是Rhizobium和Bradyrhizobium的新类群,另外3个代表菌株分别位于Sinorhizobium、Mesorhizobium、Bradyrhizobium分支,分别与S.americanum、M.Plurifarium、R.huautlense亲缘关系最近。无氮水培接种试验筛选出2个共生固氮效果好、与不接种对照处理差异达显著水平的菌株SCAU229和SCAU307,有3个菌株不仅不具共生有效性,甚至不利于宿主的生长,其余84%的供试菌为低效或无效菌株。【结论】凉山州新银合欢根瘤菌具有丰富的遗传多样性,分布于4个属:Rhizobium、Bradyrhizobium、Mesorhizobium、Bradyrhizobium,79%为Sinorhizobium属的菌株,优势菌群为Sinorhizobium。该区的新银合欢根瘤菌大多数的共生有效性差。     

山蚂蝗慢生根瘤菌的遗传多样性及系统发育

摘要:【目的】研究我国亚热带和温带地区与山蚂蝗共生的慢生根瘤菌遗传多样性和系统发育。【方法】采用BOX-PCR 和多位点基因序列分析(nifH,nodC 和recA 基因) 方法对分离自我国不同地区的29 株山蚂蝗慢生根瘤菌进行遗传多样性和系统发育分析。【结果】BOX-PCR 分析表明供试的山蚂蝗慢生根瘤菌形成25个基因遗传型,具有丰富的基因组多样性。多位点基因序列分析发现代表菌株位于慢生根瘤菌的3 个分支上,分别与埃氏慢生根瘤菌(Bradyrhizobium elkanii) ,大豆慢生根瘤菌( Bradyrhizobium japonicum) 和圆明慢生根瘤菌(Bradyrhizobium yuanmingense) 亲缘关系近。【结论】我国山蚂蝗慢生根瘤菌具有丰富的遗传多样性,共生基因系统发育分析表明它们多与持家基因共同进化,并以垂直进化为主。     

沙冬青根瘤菌遗传多样性和系统发育分析

利用16S rDNA RFLP、16S-23S rDNA RFLP和16S rDNA序列分析方法,对分离自宁夏和内蒙古阿拉善地区的沙冬青根瘤菌进行了遗传多样性和系统发育分析.结果表明,分离自不同地区沙冬青根瘤菌的44株测试菌株分别归属于中慢生根瘤菌属(Mesorhizobium)、叶杆菌属 (Phylobacterium)、中华根瘤菌属(Sinorhizobium)、根瘤菌属(Rhizobium)、土壤杆菌属(Agrobacterium)5个属种.受寄主和地理环境因素的影响,沙冬青根瘤菌具有丰富的遗传多样性.     

云南省德宏州含羞草β-根瘤菌多样性及系统发育研究

【目的】通过对分离自云南德宏州的含羞草β-根瘤菌进行遗传与表型多样性研究,揭示我国含羞草β-根瘤菌的物种多样性。【方法】应用16S rDNA PCR-RFLP、全细胞蛋白SDS-PAGE电泳及16S rDNA全序列分析对分离得到的60株含羞草根瘤菌进行多样性研究。【结果】16S rDNA PCR-RFLP及全细胞蛋白SDS-PAGE图谱分析将供试菌株分为2个遗传型群和2个表型群,分别与贪铜菌属(Cupriavidus)和伯克霍尔德菌属(Burkholderia)参比菌株聚群。经16S rDNA全序列分析,供试菌株被归到台湾贪铜菌(Cupriavidus taiwanensis)、含羞草伯克霍尔德菌(Burkholderia mimosarum)及结瘤伯克霍尔德菌(Burkholderia phymatum)等3个种群。【结论】云南德宏州的含羞草β-根瘤菌主要为贪铜菌及伯克霍尔德菌类群,其中贪铜菌占绝对优势,且存在遗传和表型的丰富多样性,该研究揭示了含羞草β-根瘤菌的物种多样性并丰富了我国β-根瘤菌菌种资源。     

Genetic diversity of Bradyrhizobium strains isolated from Arachis hypogaea

Rhizobia are used exclusively in agricultural systems for enhancing the ability of legumes to fix atmospheric nitrogen. Knowledge about the indigenous population is necessary for the selection and application of inoculant strains. In this study, we have assessed the genetic diversity of Bradyrhizobium strains isolated from the host plant, Arachis hypogaea along the coastline of Tamil Nadu. Different populations collected from varying environmental conditions were analysed for salt and pH tolerance. Genetic diversity among the strains was studied using RAPD markers and PCR-RFLP of 16S rDNA and nifD genes. The approaches used in this study yielded consistent results, which revealed a high degree of heterogeneity among strains and detection of two distinct genetic groups.     

金沙江干热河谷区田菁根瘤菌多样性与系统发育

[目的]揭示金沙江干热河谷区这一特殊地理环境下田菁根瘤菌的多样性和系统发育地位. [方法]采用了数值分类、16S rDNA PCR-RFLP、16S rDNA和GSⅡ序列分析方法.[结果]数值分类结果表明:在93%的水平上,待测菌株分布于6个群,其中4个群分别与R.tropici、 R.etli、 S.saheli、A.rubi的参比菌株聚在一起,两个群没有参比菌株与之聚群.16S rDNA PCR-RFLP结果与数值分类基本一致,只有两个独立群有所差异.16S rDNA序列分析表明:两独立群中心菌株SCAU176 和SCAU144与R.huautlense聚在一起,与该种同源性分别为100%和98.9%.GSⅡ序列分析中SCAU176 和SCAU144单独聚在一起,与最近的参比菌株R.tropici的同源性系数在90%以下.[结论]金沙江干热河谷区田菁根瘤菌具有较为丰富的多样性,在系统发育地位上分布于Sinorhizobium、Agrobacterium和Rhizobium三个属.     

Genetic diversity of Ornithobacterium rhinotracheale strains isolated from poultry in France

Twenty-three strains of Ornithobacterium rhinotracheale from various origins, associated with respiratory pathology of birds, were compared using plasmid profiles, ribotyping and Random Amplified Polymorphic DNA (RAPD) in order to achieve a precise strain characterization as well as to highlight the relationships between these strains. No plasmid could be detected. These strains were poorly discriminated by ribotyping although different enzymes were used. The RAPD analysis has given reproducible DNA fingerprints and a good level of discrimination. This method can be used with only one or two primers to differentiate the O. rhinotracheale strains and could be used in epidemiological studies.     

Purification and Characterization at Phosphomannomutase from Fresh Seeds of Sesbania cannabina

Phosphomannomutase (PMM) was isolated and further purified from the fresh seeds of Sesbania cannabina by using preparative Sephadex G-200 slab IEF. The pH of Sesbania PMM was 5.0. Purified PMM showed a distinct band on SDS-PAGE with the molecular weight of 41 kD. The pH value for optimum catalysis of the enzyme was 7.3 at 30℃, and the equilibrium constant of PMM reaction was 16.2. In addition, the amino acid composition of the purified PMM was measured which conformed the property of acidic protein.     

Genetic diversity and technological properties of Streptococcus thermophilus strains isolated from dairy products

AIMS: To evaluate the genetic diversity and the technological properties of 44 strains of Streptococcus thermophilus isolated from dairy products. Methods METHODS AND RESULTS: Strains were analysed for some relevant technological properties, i.e. exopolysaccharide (EPS) production, growth kinetic in skim milk medium, urease activity and galactose fermentation. The EPS production, determined by evaluating the colour of the colonies grown in ruthenium red milk agar, was observed in 50% of the analysed strains. Urease activity, determined by colorimetric and conductimetric methods, showed that 91% of the isolates, all except four, could hydrolyse urea. A conductimetric approach was also used for the evaluation of the overall metabolic behaviour in milk of Strep. thermophilus strains and the differences observed allowed grouping of the strains in seven different clusters. A total of 11 strains were able to produce acid in presence of galactose. Genetic diversity of Streptococcus thermophilus strains, evaluated by Random Amplified Polymorphic DNA fingerprinting (RAPD) and amplified epsC-D restriction analysis, allowed the identification of 21 different genotypes. CONCLUSIONS: Comparison between the genotypic and phenotypic data highlights an interesting correlation between some important technological properties and well-defined genotypes. SIGNIFICANCE AND IMPACT OF THE STUDY: The genetic and technological characterization carried out on several Strep. thermophilus strains of dairy origin should expand the knowledge on this important lactic acid bacteria species and lead to a simple, rapid, and reliable identification of strains on the basis of well-defined biotechnological properties.     

Genetic and phenotypic diversity of Saccharomyces sensu stricto strains isolated from Amarone wine

Individual yeast strains belonging to the Saccharomyces sensu stricto complex were isolated from Amarone wine produced in four cellars of the Valpolicella area (Italy) and characterized by conventional physiological tests and by RAPD-PCR and mtDNA restriction assays. Thirteen out of 20 strains were classified as Saccharomyces cerevisiae (ex S. cerevisiae p.r. cerevisiae and p.r. bayanus) and the remaining as Saccharomyces bayanus (ex S. cerevisiae p.r. uvarum). RAPD-PCR method proved to be a fast and reliable tool for identification of Saccharomyces sensu stricto strains and also gave intraspecific differentiation. Restriction analysis of mtDNA permitted to distinguish S. cerevisiae and S. bayanus species and to discern polymorphism among S. cerevisiae isolates. The assessment of the phenotypic diversity within the isolates by gas-chromatographic analysis of secondary fermentation products was explored. Small quantities of isobutanol were produced by most of the strains and higher amounts by some S. cerevisiae strains with phenotypes Gal^- and Mel^-; all S. bayanus strains produced low amounts of amilyc alcohols. From this study it appears that each winery owns particular strains, with different genetic and biochemical characteristics, selected by specific environmental pressures during the Amarone winemaking process carried out at low temperature in presence of high sugar content.     

Genetic diversity of non-pathogenic Clavibacter strains isolated from tomato seeds

Clavibacter michiganensis subsp. michiganensis (Cmm) is a seed-transmitted, quarantine pathogen which causes bacterial wilt and canker of tomato. Despite efforts to prevent seed contamination, new introductions are regularly detected, associated with new regions of tomato seed production. It seems as if the expanding diversity of Cmm also challenges the limited host range.     

Genetic diversity of Cylindrospermopsis strains (cyanobacteria) isolated from four continents

The genetic diversity of Cylindrospermopsis strains (cyanobacteria) was examined using mainly the 16S-23S internally transcribed spacer (ITS1) sequences. Strains were grouped in three clusters: (i) America, (ii) Europe, and (iii) Africa and Australia. These results suggested a recent spread of Cylindrospermopsis across the American and European continents from restricted warm refuge areas instead of exchanges between continents. On the other hand, they also suggested a recent colonization of Australia by African strains.     

Genetic and biochemical diversity of Gardnerella vaginalis strains isolated from women with bacterial vaginosis

Gardnerella vaginalis is considered a substantial player in the progression of bacterial vaginosis (BV). We analysed 17 G. vaginalis strains isolated from the genital tract of women diagnosed with BV to establish a potential link between genotypes/biotypes and the expression of virulence factors, vaginolysin (VLY) and sialidase, which are assumed to play a substantial role in the pathogenesis of BV. Amplified ribosomal DNA restriction analysis revealed two G. vaginalis genotypes. Gardnerella vaginalis isolates of genotype 2 appeared more complex than genotype 1 and were subdivided into three subtypes. Biochemical typing allowed us to distinguish four different biotypes. A great diversity of the level of VLY production among the isolates of G. vaginalis may be related to a different cytotoxicity level of the strains. We did not find any correlation between VLY production level and G. vaginalis genotype/biotype. In contrast, a link between G. vaginalis genotype and sialidase production was established. Our findings on the diversity of VLY expression level in different clinical isolates and linking sialidase activity with the genotype of G. vaginalis could help to evaluate the pathogenic potential of different G. vaginalis strains.