title: Beijerinckia derxii releases plant growth regulators and amino acids in synthetic media independent of nitrogenase activity.
abstract: OBJECTIVE
  This study aims at evaluating the ability of Beijerinckia derxii, a free-living nitrogen (N)-fixing bacterium frequently isolated from tropical soils, to release certain plant growth regulators [indoleacetic acid (IAA), ethylene, polyamines] and amino acids into the growth medium.
  
  
  RESULTS
  The production of those substances was compared using both cultures in which nitrogenase was active (N-free medium) and cultures in which nitrogenase was repressed (combined-N cultures). Those cultures were grown under agitation and in absence of agitation. Total IAA production was higher in agitated, N-free cultures but specific production was greater in combined-N cultures under agitation. Putrescine and spermidine were detected under all conditions tested. Ethylene was produced in both N-free and combined-N cultures. A greatest diversity of amino acids was released in N-free cultures.
  
  
  CONCLUSIONS
  There was no inhibition of the production of the analysed substances under conditions where nitrogenase was inactive.
  
  
  CONCLUSIONS
  Beijerinckia derxii is potentially a producer of plant-active substances; its presence in the natural environment suggests that this bacterium may contribute to the development of other living organisms.
authors.affiliation: Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brasil.
authors.forename: D S
authors.initials: DS
authors.lastname: Thuler
authors.forename: E I S
authors.initials: EI
authors.lastname: Floh
authors.forename: W
authors.initials: W
authors.lastname: Handro
authors.forename: H R
authors.initials: HR
authors.lastname: Barbosa
mesh_terms: D000596:Amino Acids / Q000378:metabolism*; D042062:Beijerinckiaceae / Q000378:metabolism*; D003470:Culture Media; D005030:Ethylenes / Q000096:biosynthesis; D007210:Indoleacetic Acids / Q000378:metabolism; D009591:Nitrogenase / Q000378:metabolism*; D010937:Plant Growth Regulators / Q000096:biosynthesis*; D011073:Polyamines / Q000378:metabolism; D011700:Putrescine / Q000032:analysis; D012988:Soil Microbiology; D013095:Spermidine / Q000032:analysis
chemical_list: D000596:Amino Acids; D003470:Culture Media; D005030:Ethylenes; D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; D011073:Polyamines; C030737:indoleacetic acid; C036216:ethylene; D009591:Nitrogenase; D013095:Spermidine; D011700:Putrescine