Enzymically mediated bioprecipitation of uranium by a Citrobacter sp. : a concerted role for exocellular lipopolysaccharide and associated phosphatase in biomineral formation.

A Citrobacter sp. accumulated uranyl ion (UO2(2+)) via precipitation with phosphate ligand liberated by phosphatase activity. The onset and rate of uranyl phosphate deposition were promoted by NH4(+), forming NH(4)UO(2)PO(4), which has a lower solubility product than NaUO(2)PO(4).

Iron acquisition from transferrin and lactoferrin by Pseudomonas aeruginosa pyoverdin.

Growth of Pseudomonas aeruginosa ATCC 15692 was promoted when the strain was cultured in an iron-depleted succinate medium, supplemented with transferrin at 30%, 60% and 100% and lactoferrin at 60% and 100% iron-saturation. No significant differences between cell growth and pyoverdin production were observed when transferrin iron saturation was increased from 30% to 100%; however, cell growth and pyoverdin production were strongly dependent on lactoferrin iron saturation. Lower lactoferrin iron saturation (< 30%) resulted in more pyoverdin production and reduced cell growth.

Localization of enzymically enhanced heavy metal accumulation by Citrobacter sp. and metal accumulation in vitro by liposomes containing entrapped enzyme.

A heavy-metal-accumulating Citrobacter sp. has been used for the treatment of metal-laden industrial wastes. Metal uptake is mediated via a cell-bound phosphatase that liberates inorganic phosphate which precipitates with heavy metals as cell-bound metal phosphate.