|Van Berkum, Peter|
Submitted to: Systematic and Applied Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/4/2005
Publication Date: 2/4/2006
Citation: Van Berkum, P.B., Eardly, B.D., Leibold, J.M. 2006. Proposal for combining bradyrhizobium spp. (aeschynomene indica) with blastobacter denitrificans and to transfer blastobacter denitrificans (hirsh and muller 1985) to the genus bradyrhizobium as bradyrhizobium denitrificans. Systematic and Applied Microbiology 29:207-213.
Interpretive Summary: Bacteria influence agriculture; they can be beneficial or be harmful. Bacteria that form a symbiosis with legumes are called rhizobia and they are beneficial since they are essential for low input sustainable agriculture. However, very little is known about communities of rhizobia and about the habitats they occupy. This knowledge is necessary for the successful management of the symbiosis in agriculture for efficient crop production. The scope of a rhizobial community was investigated by comparing properties of bacteria isolated from a tropical legume and those originating from lake water in a temperate region. The properties that were examined in both groups of bacteria were found to be the same. Therefore, we proposed that both these groups of bacteria instead of having a separate classification should be grouped together in the same genus and species. This information is useful for microbiologists, microbial ecologists and taxonomists.
Technical Abstract: The symbiotic bradyrhizobia of Aeschynomene indica and the aquatic budding bacterium Blastobacter denitrificans have much in common and this study broadens the characters that are shared between the two. The 23S rRNA gene sequences of the bradyrhizobial isolates were most similar to each other and to the sequence of Bl. denitrificans. Evidence for the presence of photosynthetic genes in the genome of Bl. denitrificans was obtained by PCR using primers to the conserved M subunit (pufM) of the photosynthetic reaction center present in purple sulfur and purple nonsulfur bacteria. The deduced amino acid sequences of the partial PufM protein of Bl. denitrificans and the corresponding sequences obtained from the bradyrhizobial isolates were identical. Both the bradyrhizobial isolates and the type strain of Bl. denitrificans shared the ability to propagate by budding, demonstrated by electron microscopy. Even though many interspecific characters were shared among the bradyrhizobial isolates including Bl. denitrificans, it was evident from Amplified Fragment Length Polymorphism (AFLP) analysis that genomic variation existed among the collection that was examined. Variation among bradyrhizobial isolates and Bl. denitrificans also was established in carbon and nitrogen source utilization and the ability to grow at elevated temperature. Based on these results and previously reported evidence it is suggested that the type strain for Bl denitrificans and the bradyrhizobial isolates from nodules of A. indica belong to a common group of bacteria. Therefore, it is proposed that they be combined into the genus Bradyrhizobium and that LMG 8443 be transferred to this genus as the type strain for B. denitrificans