title: Bacteria isolated from soils of the western Amazon and from rehabilitated bauxite-mining areas have potential as plant growth promoters.
abstract: Several processes that promote plant growth were investigated in endophytic and symbiotic bacteria isolated from cowpea and siratro nodules and also in bacterial strains recommended for the inoculation of cowpea beans. The processes verified in 31 strains were: antagonism against phytopathogenic fungi, free-living biological nitrogen fixation, solubilization of insoluble phosphates and indole acetic acid (IAA) production. The resistance to antibiotics was also assessed. Sequencing of the partial 16S rRNA gene was performed and the strains were identified as belonging to different genera. Eight strains, including some identified as Burkholderia fungorum, fixed nitrogen in the free-living state. Eighteen strains exhibited potential to solubilize calcium phosphate, and 13 strains could solubilize aluminum phosphate. High levels of IAA production were recorded with L-tryptophan addition for the strain UFLA04-321 (42.3 μg mL⁻¹). Strains highly efficient in symbiosis with cowpea bean, including strains already approved as inoculants showed the ability to perform other processes that promote plant growth. Besides, these strains exhibited resistance to several antibiotics. The ability of the nitrogen-fixing bacteria to perform other processes and their adaptation to environmental conditions add value to these strains, which could lead to improved inoculants for plant growth and environmental quality.
authors.affiliation: Postgraduate Program of Agricultural Microbiology, Department of Biology, Federal University of Lavras, P.O 3037, Lavras, MG, 37200-000, Brazil, sylmarya@yahoo.com.br.
authors.forename: Silvia Maria
authors.initials: SM
authors.lastname: de Oliveira-Longatti
authors.forename: Leandro Marciano
authors.initials: LM
authors.lastname: Marra
authors.forename: Bruno
authors.initials: B
authors.lastname: Lima Soares
authors.forename: Cleide Aparecida
authors.initials: CA
authors.lastname: Bomfeti
authors.forename: Krisle
authors.initials: K
authors.lastname: da Silva
authors.forename: Paulo Ademar
authors.initials: PA
authors.lastname: Avelar Ferreira
authors.forename: Fatima Maria
authors.initials: FM
authors.lastname: de Souza Moreira
mesh_terms: D017607:Aluminum Compounds / Q000378:metabolism; D001419:Bacteria / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D024881:Drug Resistance, Bacterial; D007210:Indoleacetic Acids / Q000378:metabolism; D056265:Microbial Interactions; D008969:Molecular Sequence Data; D009586:Nitrogen Fixation; D010710:Phosphates / Q000378:metabolism; D010802:Phylogeny; D063245:Plant Development; D010944:Plants / Q000382:microbiology; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012988:Soil Microbiology
chemical_list: D017607:Aluminum Compounds; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D007210:Indoleacetic Acids; D010710:Phosphates; D012336:RNA, Ribosomal, 16S; C030737:indoleacetic acid; C012714:aluminum phosphate