ABSTRACT
Binding of Cr to P. aeruginosa whole cells increased with an increase in positive charge of the chromium complexes used. Distribution of Cr bound from aqueous solutions of potassium dichromate--a Cr(VI) salt and basic chromium sulphate (BCS)--a Cr(III) salt [used for tanning which has 25% of Cr2O3 on weight basis and is of 33% basicity (one hydroxyl/Cr atom)] was more in soluble fraction (protein and nucleic acids) than in insoluble fraction (lipids, polyphosphates, polysaccharides, lipopolysaccharides and mucopeptides). Electron spin resonance spectrum of the cells exposed to hexavalent chromium revealed the presence of Cr(III) ion demonstrating a reduction of the same by the Pseudomoas. The infrared spectra of chromium exposed cell envelopes support that protein carboxylic sites and proteins are involved in binding Cr(III) and predominantly lipids in Cr(VI). Bound chromium could be removed chemically and the cells could then be reused as a biosorbent.
Subject(s)
Cell Fractionation , Cell Membrane/chemistry , Chemistry, Physical , Chromium/analysis , Membrane Proteins/chemistry , Chemical Phenomena , Protein Binding , Pseudomonas aeruginosa/chemistry , SolubilityABSTRACT
Tolerance level to trivalent chromium-Cr(salen)(H2O)2+ and hexavalent chromium-K2Cr2O7 was assessed in P. aeruginosa isolated from tannery effluent soil. It could tolerate 80 and 100 ppm in liquid cultures and up to 100 and 200 ppm in plate count agar in the presence of trivalent and hexavalent chromium respectively. Unadapted cells took a longer time to grow than adapted cells in the presence of K2Cr2O7. Chromium influenced the cellular contents, morphology and respiration of P. aeruginosa. The chosen trivalent salt of chromium was more toxic than the hexavalent one.