Genetic diversity amongBradyrhizobiumisolates that effectively nodulate peanut (Arachis hypogaea)

1996 ◽  
Vol 42 (11) ◽  
pp. 1121-1130 ◽  
Author(s):  
Bruce E. Urtz ◽  
Gerald H. Elkan
Keyword(s):  
Genetic Diversity ◽  
Restriction Fragment Length Polymorphism ◽  
16S Rrna ◽  
Arachis Hypogaea ◽  
Length Polymorphism ◽  
Fragment Length ◽  
Fragment Length Polymorphism ◽  
Dna Homology ◽  
Symbiotic Gene ◽  
Restriction Fragment Length

Symbiotic gene diversity and other measures of genetic diversity were examined in Bradyrhizobium isolates that form an effective symbiosis with peanut (Arachis hypogaea). Initially, restriction fragment length polymorphism (RFLP) analysis using a nitrogenase (nif) gene probe was performed on 33 isolates along with one Bradyrhizobium elkanii and two Bradyrhizobium japonicum strains. Considerable diversity was observed among the RFLP patterns of many of the isolates, especially those from South America. Some isolates, however, were found to have similar nif and subsequent nod (nodulation) gene RFLP patterns, indicating symbiotic gene relatedness. With some noted exceptions, symbiotic gene relatedness correlated with relatedness based on total DNA homology and ribotyping analyses. Symbiotic gene relatedness also correlated with symbiotic effectiveness. The RFLP and DNA homology analyses indicate that bradyrhizobia effective with peanut are genetically diverse and consist of at least three different species. This diversity, however, was not particularly evident with partial 16S rRNA gene sequencing. Sequences obtained from the isolates were very similar to each other as well as to sequences previously reported for other Bradyrhizobium strains.Key words: Bradyrhizobium, nif, peanut, restriction fragment length polymorphism, 16S rRNA.

scholarly journals Analysis of the Endophytic Actinobacterial Population in the Roots of Wheat (Triticum aestivum L.) by Terminal Restriction Fragment Length Polymorphism and Sequencing of 16S rRNA Clones

2004 ◽  
Vol 70 (3) ◽  
pp. 1787-1794 ◽  
Author(s):  
Vanessa M. Conn ◽  
Christopher M. M. Franco
Keyword(s):  
Restriction Fragment Length Polymorphism ◽  
16S Rrna ◽  
Restriction Fragment ◽  
Length Polymorphism ◽  
Fragment Length ◽  
Fragment Length Polymorphism ◽  
Rflp Analysis ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Restriction Fragment Length

ABSTRACT The endophytic actinobacterial population in the roots of wheat grown in three different soils obtained from the southeast part of South Australia was investigated by terminal restriction fragment length polymorphism (T-RFLP) analysis of the amplified 16S rRNA genes. A new, validated approach was applied to the T-RFLP analysis in order to estimate, to the genus level, the actinobacterial population that was identified. Actinobacterium-biased primers were used together with three restriction enzymes to obtain terminal restriction fragments (TRFs). The TRFs were matched to bacterial genera by the T-RFLP Analysis Program, and the data were analyzed to validate and semiquantify the genera present within the plant roots. The highest diversity and level of endophytic colonization were found in the roots of wheat grown in a dark loam from Swedes Flat, and the lowest were found in water-repellent sand from Western Flat. This molecular approach detected a greater diversity of actinobacteria than did previous culture-dependent methods, with the predominant genera being Mycobacterium (21.02%) in Swedes Flat, Streptomyces (14.35%) in Red Loam, and Kitasatospora (15.02%) in Western Flat. This study indicates that the soil that supported a higher number of indigenous organisms resulted in wheat roots with higher actinobacterial diversity and levels of colonization within the plant tissue. Sequencing of 16S rRNA clones, obtained using the same actinobacterium-biased PCR primers that were used in the T-RFLP analysis, confirmed the presence of the actinobacterial diversity and identified a number of Mycobacterium and Streptomyces species.

scholarly journals Detection and Characterization of a Dehalogenating Microorganism by Terminal Restriction Fragment Length Polymorphism Fingerprinting of 16S rRNA in a Sulfidogenic, 2-Bromophenol-Utilizing Enrichment

2004 ◽  
Vol 70 (2) ◽  
pp. 1169-1175 ◽  
Author(s):  
Donna E. Fennell ◽  
Sung-Keun Rhee ◽  
Young-Beom Ahn ◽  
Max M. Häggblom ◽  
Lee J. Kerkhof
Keyword(s):  
Restriction Fragment Length Polymorphism ◽  
16S Rrna ◽  
Restriction Fragment ◽  
Length Polymorphism ◽  
Fragment Length ◽  
Fragment Length Polymorphism ◽  
Reductive Dehalogenation ◽  
Polymorphism Analysis ◽  
Sulfate Reducing ◽  
Restriction Fragment Length

ABSTRACT Terminal restriction fragment length polymorphism analysis of reverse-transcribed 16S rRNA during periods of community flux was used as a tool to delineate the roles of the members of a 2-bromophenol-degrading, sulfate-reducing consortium. Starved, washed cultures were amended with 2-bromophenol plus sulfate, 2-bromophenol plus hydrogen, phenol plus sulfate, or phenol with no electron acceptor and were monitored for substrate use. In the presence of sulfate, 2-bromophenol and phenol were completely degraded. In the absence of sulfate, 2-bromophenol was dehalogenated and phenol accumulated. Direct terminal restriction fragment length polymorphism fingerprinting of the 16S rRNA in the various subcultures indicated that phylotype 2BP-48 (a Desulfovibrio-like sequence) was responsible for the dehalogenation of 2-bromophenol. A stable coculture was established which contained predominantly 2BP-48 and a second Desulfovibrio-like bacterium (designated BP212 based on terminal restriction fragment length polymorphism fingerprinting) that was capable of dehalogenating 2-bromophenol to phenol. Strain 2BP-48 in the coculture could couple reductive dehalogenation to growth with 2-bromophenol, 2,6-dibromophenol, or 2-iodophenol and lactate or formate as the electron donor. In addition to halophenols, strain 2BP-48 appears to use sulfate, sulfite, and thiosulfate as electron acceptors and is capable of simultaneous sulfidogenesis and reductive dehalogenation in the presence of sulfate.

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