Recently, many β-proteobacteria have joined the established α-proteobacteria as capable of effect... more Recently, many β-proteobacteria have joined the established α-proteobacteria as capable of effectively nodulating legumes. However, despite their isolation from nodules of papilionoid and other mimosoid legumes (Moulin et al., 2001; Barrett and Parker, 2005), there is little evidence that these β-proteobacteria effectively nodulate any legume outside the sub-family Mimosoideae.
It is now well established that many species and strains in the large genus Burkholderia have the... more It is now well established that many species and strains in the large genus Burkholderia have the ability to fix nitrogen in free-living culture, particularly those, such as B. tropica, B. unamae and B. Vietnamiensis, that are associated with (mainly tropical) gramineous plants (Reis et al., 2004). Many Burkholderia strains have also been found within nodules of tropical legumes (Moulin et al., 2001), particularly in nodules on Mimosa spp.(Barrett and Parker, 2005, 2006; Chen et al., 2005a, b).
In 2001, the first identification of β-proteobacteria, which belong to the Burkholderia and Ralst... more In 2001, the first identification of β-proteobacteria, which belong to the Burkholderia and Ralstonia genera and are able to nodulate legumes, has changed the long-held perception that legumes can only form nitrogen-fixing symbioses with bacteria in the α-proteobacteria subgroup (Moulin et al., 2001).
Environmental screening of bacteria for the presence of genes of interest is a challenging proble... more Environmental screening of bacteria for the presence of genes of interest is a challenging problem, due to the high variability of the nucleotide sequence of a given gene between species. Here, we tackle this general issue using a particularly well-suited model system that consists of the nodulation gene nodC, which is shared by phylogenetically distant rhizobia. 41mer and 50mer oligonucleotides featuring the nucleotide diversity of two highly conserved regions of the NodC protein were spotted on glass slides and cross hybridized with the radioactive-labeled target genomic DNA under low-stringency conditions. Statistical analysis of the hybridization patterns allowed the detection of known, as well as new, nodC sequences and classified the rhizobial strains accordingly. The microarray was successfully used to type the nodC gene directly from legume nodules, thus eliminating the need of cultivation of the endosymbiont. This approach could be extended to a panel of diagnostic genes and constitute a powerful tool for studying the distribution of genes of interest in the environment, as well as for bacteria identification.
Recently, many β-proteobacteria have joined the established α-proteobacteria as capable of effect... more Recently, many β-proteobacteria have joined the established α-proteobacteria as capable of effectively nodulating legumes. However, despite their isolation from nodules of papilionoid and other mimosoid legumes (Moulin et al., 2001; Barrett and Parker, 2005), there is little evidence that these β-proteobacteria effectively nodulate any legume outside the sub-family Mimosoideae.
It is now well established that many species and strains in the large genus Burkholderia have the... more It is now well established that many species and strains in the large genus Burkholderia have the ability to fix nitrogen in free-living culture, particularly those, such as B. tropica, B. unamae and B. Vietnamiensis, that are associated with (mainly tropical) gramineous plants (Reis et al., 2004). Many Burkholderia strains have also been found within nodules of tropical legumes (Moulin et al., 2001), particularly in nodules on Mimosa spp.(Barrett and Parker, 2005, 2006; Chen et al., 2005a, b).
In 2001, the first identification of β-proteobacteria, which belong to the Burkholderia and Ralst... more In 2001, the first identification of β-proteobacteria, which belong to the Burkholderia and Ralstonia genera and are able to nodulate legumes, has changed the long-held perception that legumes can only form nitrogen-fixing symbioses with bacteria in the α-proteobacteria subgroup (Moulin et al., 2001).
Environmental screening of bacteria for the presence of genes of interest is a challenging proble... more Environmental screening of bacteria for the presence of genes of interest is a challenging problem, due to the high variability of the nucleotide sequence of a given gene between species. Here, we tackle this general issue using a particularly well-suited model system that consists of the nodulation gene nodC, which is shared by phylogenetically distant rhizobia. 41mer and 50mer oligonucleotides featuring the nucleotide diversity of two highly conserved regions of the NodC protein were spotted on glass slides and cross hybridized with the radioactive-labeled target genomic DNA under low-stringency conditions. Statistical analysis of the hybridization patterns allowed the detection of known, as well as new, nodC sequences and classified the rhizobial strains accordingly. The microarray was successfully used to type the nodC gene directly from legume nodules, thus eliminating the need of cultivation of the endosymbiont. This approach could be extended to a panel of diagnostic genes and constitute a powerful tool for studying the distribution of genes of interest in the environment, as well as for bacteria identification.
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