Palladium has no know biological function and palladium compounds are toxic to both prokaryotic and eukaryotic
(Khan et al, 1991). Palladium is a precious metal of industrial importance, and biological methods to recover
palladium from solution have been explored, as chemical recovery methods are inefficient.
Desulfovibrio desulfuricans was found to reduce Pd(II) to Pd(0) using formate or
H2 as an electron donor, with concomitant accumulation of the reduced metal on cell surfaces (Lloyd et al, 2002). The authors propose that D. desulfuricans reduces palladium enzymatically.
D. desulfuricans resting cells and biomass from other organisms have been evaluated as biosorbents to passively
remove soluble palladium from solution (Yong et
al, 2002; Remoudaki et al, 1999). The transfer of a methyl group to palladium from the vitamin B12 derivative
methylcobablamin has been reported in vitro, but the methylated palladium species was not stable (Scovell, 1974).
For more information:
Medline for palladium metabolism AND bacteria
Remoudaki E, Tsezos M, Hatzikioseyian A, Karakoussis Y. Mechanism of palladium biosorption by microbial biomass. The
effects of metal ionic speciation and solution co-ions. Process Metallurgy 1999;9B:449-62.
Scovell WH. Kinetics and mechanism of methyl transfer from methylcobalamin to palladium(II). J Am Chem Soc. 1974;96:
Yong P, Rowson NA, Farr JPG, Harris IR, Macaskie LE. Bioaccumulation of palladium by Desulfovibrio desulfuricans.
J Chem Technol Biotechnol. 2002;77:593-601.