title: High diversity of Bradyrhizobium strains isolated from several legume species and land uses in Brazilian tropical ecosystems.
abstract: The genus Bradyrhizobium stands out among nitrogen-fixing legume-nodulating bacteria because it predominates among the efficient microsymbionts of forest, forage, and green manure legume species, as well as important species of grain legumes, such as soybean, cowpea, and peanut. Therefore, the diversity of Bradyrhizobium strains is a relevant resource from environmental and economic perspectives, and strains isolated from diverse legume species and land uses in Brazilian tropical ecosystems were assessed in this study. To accomplish this, sequences of four housekeeping genes (atpD, dnaK, gyrB, and recA) were individually analysed, with the first three also being considered using multilocus sequence analysis (MLSA). The sensitivity of the strains to different antibiotics, their tolerance to different levels of salinity, and their ability to nodulate soybean plants were also measured. The phylogenetic trees based on each individual gene, and on the concatenated housekeeping genes, revealed several strain clusters separated from any currently described species. The Bradyrhizobium strains studied were generally resistant to antibiotics. All strains were able to grow at salinity levels of up to 0.5% NaCl, whereas only strains UFLA03-142, UFLA03-143, UFLA03-145, and UFLA03-146 grew in the presence of 1% NaCl. Together, the results indicated that some of the strains studied were potential novel species, indicating that the various soils and ecosystems in Brazil may harbour an as yet unknown diversity of rhizobia.
authors.affiliation: Setor de Biologia, Microbiologia e Processos Biológicos do Solo, Departamento de Ciência do Solo, Universidade Federal de Lavras, Campus UFLA, 37200-000 Lavras, Minas Gerais, Brazil.
authors.forename: Amanda
authors.initials: A
authors.lastname: Azarias Guimarães
authors.affiliation: Setor de Biologia, Microbiologia e Processos Biológicos do Solo, Departamento de Ciência do Solo, Universidade Federal de Lavras, Campus UFLA, 37200-000 Lavras, Minas Gerais, Brazil.
authors.forename: Ligiane Aparecida
authors.initials: LA
authors.lastname: Florentino
authors.affiliation: Setor de Biologia, Microbiologia e Processos Biológicos do Solo, Departamento de Ciência do Solo, Universidade Federal de Lavras, Campus UFLA, 37200-000 Lavras, Minas Gerais, Brazil.
authors.forename: Kize
authors.initials: K
authors.lastname: Alves Almeida
authors.affiliation: Laboratory of Microbiology, Department of Biochemistry and Microbiology, Ghent University, K.L. Ledeganckstraat 35, B-9000 Ghent, Belgium.
authors.forename: Liesbeth
authors.initials: L
authors.lastname: Lebbe
authors.affiliation: Setor de Biologia, Microbiologia e Processos Biológicos do Solo, Departamento de Ciência do Solo, Universidade Federal de Lavras, Campus UFLA, 37200-000 Lavras, Minas Gerais, Brazil.
authors.forename: Karina
authors.initials: K
authors.lastname: Barroso Silva
authors.affiliation: Laboratory of Microbiology, Department of Biochemistry and Microbiology, Ghent University, K.L. Ledeganckstraat 35, B-9000 Ghent, Belgium.
authors.forename: Anne
authors.initials: A
authors.lastname: Willems
authors.affiliation: Setor de Biologia, Microbiologia e Processos Biológicos do Solo, Departamento de Ciência do Solo, Universidade Federal de Lavras, Campus UFLA, 37200-000 Lavras, Minas Gerais, Brazil. Electronic address: fmoreira@dcs.ufla.br.
authors.forename: Fatima Maria
authors.initials: FM
authors.lastname: de Souza Moreira
mesh_terms: D000383:Agriculture / Q000379:methods*; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D020369:Bradyrhizobium / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification* / Q000502:physiology; D001938:Brazil; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D017753:Ecosystem; D007887:Fabaceae / Q000382:microbiology*; D020043:Genes, Essential; D014644:Genetic Variation; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D058889:Molecular Typing; D055170:Plant Root Nodulation; D012492:Salts / Q000494:pharmacology; D017422:Sequence Analysis, DNA; D014329:Tropical Climate
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D012492:Salts
keywords: Cowpea; Forest species; Housekeeping genes; Legume-nodulating bacteria; Multilocus sequence analysis; Soybean