title: Novel European free-living, non-diazotrophic Bradyrhizobium isolates from contrasting soils that lack nodulation and nitrogen fixation genes - a genome comparison.
abstract: The slow-growing genus Bradyrhizobium is biologically important in soils, with different representatives found to perform a range of biochemical functions including photosynthesis, induction of root nodules and symbiotic nitrogen fixation and denitrification. Consequently, the role of the genus in soil ecology and biogeochemical transformations is of agricultural and environmental significance. Some isolates of Bradyrhizobium have been shown to be non-symbiotic and do not possess the ability to form nodules. Here we present the genome and gene annotations of two such free-living Bradyrhizobium isolates, named G22 and BF49, from soils with differing long-term management regimes (grassland and bare fallow respectively) in addition to carbon metabolism analysis. These Bradyrhizobium isolates are the first to be isolated and sequenced from European soil and are the first free-living Bradyrhizobium isolates, lacking both nodulation and nitrogen fixation genes, to have their genomes sequenced and assembled from cultured samples. The G22 and BF49 genomes are distinctly different with respect to size and number of genes; the grassland isolate also contains a plasmid. There are also a number of functional differences between these isolates and other published genomes, suggesting that this ubiquitous genus is extremely heterogeneous and has roles within the community not including symbiotic nitrogen fixation.
authors.affiliation: Department of AgroEcology, Rothamsted Research, Harpenden, AL5 2JQ, UK.|Department of Geography and Environmental Science, University of Reading, Reading, RG6 6AH, UK.
authors.forename: Frances Patricia
authors.initials: FP
authors.lastname: Jones
authors.affiliation: Department of AgroEcology, Rothamsted Research, Harpenden, AL5 2JQ, UK.
authors.forename: Ian M
authors.initials: IM
authors.lastname: Clark
authors.affiliation: Department of Computational and Systems Biology, Rothamsted Research, Harpenden, AL5 2JQ, UK.
authors.forename: Robert
authors.initials: R
authors.lastname: King
authors.affiliation: Department of Geography and Environmental Science, University of Reading, Reading, RG6 6AH, UK.
authors.forename: Liz J
authors.initials: LJ
authors.lastname: Shaw
authors.affiliation: Department of Food and Nutritional Sciences, University of Reading, Reading, RG6 6AH, UK.
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Woodward
authors.affiliation: Department of AgroEcology, Rothamsted Research, Harpenden, AL5 2JQ, UK.
authors.forename: Penny R
authors.initials: PR
authors.lastname: Hirsch
mesh_terms: D020369:Bradyrhizobium / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D005060:Europe; D059646:Genome Size; D016680:Genome, Bacterial; D058977:Molecular Sequence Annotation; D009586:Nitrogen Fixation; D010802:Phylogeny; D055170:Plant Root Nodulation; D053204:Root Nodules, Plant / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA / Q000379:methods*; D012988:Soil Microbiology