title: Physiological and biochemical characterization of Azospirillum brasilense strains commonly used as plant growth-promoting rhizobacteria.
abstract: Azospirillum is a plant growth-promoting rhizobacteria (PGPR) genus vastly studied and utilized as agriculture inoculants. Isolation of new strains under different environmental conditions allows the access to the genetic diversity and improves the success of inoculation procedures. Historically, the isolation of this genus has been performed by the use of some traditional culture media. In this work we characterized the physiology and biochemistry of five different A. brasilense strains, commonly used as cereal inoculants. The aim of this work is to contribute to pose into revision some concepts concerning the most used protocols to isolate and characterize this bacterium. We characterized their growth in different traditional and non-traditional culture media, evaluated some PGPR mechanisms and characterized their profiles of fatty acid methyl esters and carbon-source utilization. This work shows, for the first time, differences in both profiles, and ACC deaminase activity of A. brasilense strains. Also, we show unexpected results obtained in some of the evaluated culture media. Results obtained here and an exhaustive knowledge revision revealed that it is not appropriate to conclude about bacterial species without analyzing several strains. Also, it is necessary to continue developing studies and laboratory techniques to improve the isolation and characterization protocols.
authors.affiliation: Cátedra de Microbiología Agrícola, Facultad de Agronomía, Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina.
authors.forename: Luciana P
authors.initials: LP
authors.lastname: Di Salvo
authors.forename: Esdras
authors.initials: E
authors.lastname: Silva
authors.forename: Kátia R S
authors.initials: KR
authors.lastname: Teixeira
authors.forename: Rosalba Esquivel
authors.initials: RE
authors.lastname: Cote
authors.forename: M Alejandra
authors.initials: MA
authors.lastname: Pereyra
authors.forename: Inés E
authors.initials: IE
authors.lastname: García de Salamone
mesh_terms: D015806:Azospirillum brasilense / Q000302:isolation & purification / Q000502:physiology*; D002244:Carbon / Q000378:metabolism; D019755:Carbon-Carbon Lyases / Q000378:metabolism; D018556:Crops, Agricultural / Q000254:growth & development / Q000382:microbiology; D005227:Fatty Acids / Q000378:metabolism; D007211:Indoles / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism; D017262:Siderophores / Q000096:biosynthesis; D012988:Soil Microbiology
chemical_list: D005227:Fatty Acids; D007211:Indoles; D010710:Phosphates; D017262:Siderophores; D002244:Carbon; C033634:1-aminocyclopropane-1-carboxylate deaminase; D019755:Carbon-Carbon Lyases
keywords: Agriculture sustainability; Biological nitrogen fixation; Fatty acid methyl esters analysis; Physiological profiles; Plant growth promotion mechanisms PGPR