Cadmium Accumulation by a Citrobacter sp.: the Chemical Nature of the Accumulated Metal Precipitate and its Location on the Bacterial Cells

Abstract

Cells of a strain of a Citrobacter sp., pre-grown in cadmium-free continuous culture, accumulated cadmium extensively when resuspended in a buffer that contained Cd2+ and glycerol 2-phosphate. The accumulated compound was identified by X-ray microanalysis and magic angle spinning NMR analysis as cell-bound cadmium phosphate, probably CdHPO4. Its accumulation is consistent with the activity of a phosphatase, induced during pre-growth, that continues to function in the resuspended cells to liberate HPO2− 4 from glycerol 2-phosphate. This anion then combines with Cd2+ to form insoluble cell-bound CdHPO4.