Interaction of Mercuric Ions with the Bacterial Growth Medium and Its Effects on Enzymatic Reduction of Mercury

Abstract
The interaction of Hg2+ with components of Luria‐Bertani broth (LB), used to grow the mercury‐resistant strain Pseudomonas aeruginosa PU21 (Rip64), was studied using cold vapor atomic absorption spectrometry and liquid scintillation counting. The time course analysis of free Hg2+ and total Hg in LB solutions showed that 30–40% of Hg2+ formed complexes with tryptone and yeast extract within 140 h. Media containing free or complexed Hg2+ were treated with cell‐free mercuric reductase as well as with growing cells to investigate the effect of the Hg2+‐LB interaction on mercury reduction. In both assays, it was found that the complexed Hg2+ could not be reduced by mercuric reductase or P. aeruginosa PU21 (Rip64).