SPECTROSCOPIC CHARACTERIZATION OF THE UPTAKE OF ESSENTIAL AND XENOBIOTIC METAL-CATIONS IN CELLS OF THE SOIL BACTERIUM AZOSPIRILLUM-BRASILENSE

The results of flame (FAAS) or graphite furnace atomic absorption spec trometric (GFAAS) analyses are presented and discussed on the accumula tion of essential metals (Mg, Ca, Mn and Fe contained in the cultivati on medium) and traces of each one of the conventionally xenobiotic ele ments from the group V, Co, Ni, Cu, Zn or Pb, added to the medium in c oncentrations (0.2 mM) which do not essentially suppress growth of the bacterial culture, in cells of the plant root-associated nitrogen-fix ing bacterium Azospirillum brasilense. Along with the essential cation s assimilated by the bacterium, Zn and Cu were found to effectively ac cumulate in the biomass from the environment. The uptake of Co and Ni was significantly less pronounced, whereas Pb and V appeared to be pre sent in cells in much lower concentrations than in the cultivation med ium evidently showing no tendency to be assimilated by azospirilla. Th e effect of the above xenobiotics on the uptake level of the four esse ntial elements provided evidence that they may compete for the formati on of biologically active complexes with substances of both intracellu lar and extracellular localization. The analytical data obtained are c ompared with Fourier transform infrared (FTIR) spectra of intact vacuu m-dried bacterial cells grown in a standard medium and under the condi tions of an increased metal uptake.