Resistance of Acidiplasma archaea to heavy metal ions

Effect of the ions of heavy metals (copper, zinc, and nickel) on growth of and ferrous iron oxidation by extremely acidophilic archaeal strains of the genus Acidiplasma (Acidiplasma sp. MBA-1; A. aeolicum V1T; and A. cupricumulans BH2T) was studied. Effect of the metals depending on their concentration was studied within the range from 5 to 1000 mM. All studied strains were able to oxidize iron in the presence of the highest tested heavy metal concentrations (1000 mM). All metal ions had, however, a noticeable inhibitory effect both on both growth and on iron oxidation. The lowest concentrations of copper, zinc, and nickel partially suppressing microbial growth were determined (5, 10, and 5 mM, respectively). These findings are of interest, since almost no literature data on resistance of Acidiplasma archaea to heavy metals are available, although these prokaryotes are among the most important groups of microorganisms used in biohydrometallurgy.