Cellular distribution of hexa and trivalent chromium in Pseudomonas aeruginosa

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.