Change of speciation of Cu(II) in growth medium due to uptake of ammonia by Pseudomonas testosteroni during growth.
Growth of Pseudomonas testosteroni in a medium containing 1 mM Cu(II) causes a color change from blue to green. The spectrum of the supernatant solution from the blue culture shows an absorption at 660 nm, identical to that of 1 mM [Cu(II)] in the medium. The green supernatant solution shows a UV absorption, which tails into the visible and so is responsible for the green color, and a d-d absorption at 720 nm. The absorption at 660 nm for the blue supernatant solution is probably due to [Cu(NH3)3(H2O)3]2+. Growth of the organism causes loss of ammonia and a speciation change to [CU(NH3)2(H2O)4]2+, with a shift in absorption maximum from 660 to 720 nm. These conclusions are based upon the spectra of known aquaammine complexes of Cu(II) and calculations of the speciation of Cu(II) before and after growth. Change in metal speciation owing to nutrient uptake by an organism does not appear to have been recognized previously.
Department of Chemistry, King's College London, UK.
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Ahmad
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Hughes
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Nobar
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Poole
D000641:Ammonia / Q000378:metabolism*; D003124:Colorimetry; D003300:Copper / Q000737:chemistry*; D017077:Culture Media, Conditioned / Q000737:chemistry*; D011549:Pseudomonas / Q000254:growth & development / Q000378:metabolism*
D017077:Culture Media, Conditioned; D000641:Ammonia; D003300:Copper