Standards in Genomic Sciences (Dec 2017)
Draft genome sequences of Bradyrhizobium shewense sp. nov. ERR11T and Bradyrhizobium yuanmingense CCBAU 10071T
Abstract
Abstract The type strain of the prospective Bradyrhizobium shewense sp. nov. ERR11T, was isolated from a nodule of the leguminous tree Erythrina brucei native to Ethiopia. The type strain Bradyrhizobium yuanmingense CCBAU 10071 T, was isolated from the nodules of Lespedeza cuneata in Beijing, China. The genomes of ERR11T and CCBAU 10071 T were sequenced by DOE–JGI and deposited at the DOE–JGI genome portal as well as at the European Nucleotide Archive. The genome of ERR11T is 9,163,226 bp in length and has 102 scaffolds, containing 8548 protein–coding and 86 RNA genes. The CCBAU 10071 T genome is arranged in 108 scaffolds and consists of 8,201,522 bp long and 7776 protein–coding and 85 RNA genes. Both genomes contain symbiotic genes, which are homologous to the genes found in the complete genome sequence of Bradyrhizobium diazoefficiens USDA110 T. The genes encoding for nodulation and nitrogen fixation in ERR11T showed high sequence similarity with homologous genes found in the draft genome of peanut–nodulating Bradyrhizobium arachidis LMG 26795 T. The nodulation genes nolYA-nodD2D1YABCSUIJ-nolO-nodZ of ERR11T and CCBAU 10071 T are organized in a similar way to the homologous genes identified in the genomes of USDA110 T , Bradyrhizobium ottawaense USDA 4 and Bradyrhizobium liaoningense CCBAU 05525 . The genomes harbor hupSLCFHK and hypBFDE genes that code the expression of hydrogenase, an enzyme that helps rhizobia to uptake hydrogen released by the N2-fixation process and genes encoding denitrification functions napEDABC and norCBQD for nitrate and nitric oxide reduction, respectively. The genome of ERR11T also contains nosRZDFYLX genes encoding nitrous oxide reductase. Based on multilocus sequence analysis of housekeeping genes, the novel species, which contains eight strains formed a unique group close to the B. ottawaense branch. Genome Average Nucleotide Identity (ANI) calculated between the genome sequences of ERR11T and closely related sequences revealed that strains belonging to B. ottawaense branch ( USDA4 and CCBAU15615 ), were the closest strains to the strain ERR11T with 95.2% ANI. Type strain ERR11T showed the highest DDH predicted value with CCBAU15615 (58.5%), followed by USDA 4 (53.1%). Nevertheless, the ANI and DDH values obtained between ERR11T and CCBAU 15615 or USDA 4 were below the cutoff values (ANI ≥ 96.5%; DDH ≥ 70%) for strains belonging to the same species, suggesting that ERR11T is a new species. Therefore, based on the phylogenetic analysis, ANI and DDH values, we formally propose the creation of B. shewense sp. nov. with strain ERR11T ( HAMBI 3532 T= LMG 30162 T) as the type strain.
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