Engineered Bacteria Mop Up Mercury Spills. These mercury-resistant bacteria, contained either the mouse gene for metallothionein or the bacterial gene for polyphosphate kinase. Both strains of bacteria were able to grow in very high concentrations of mercury, and when the bacteria containing metallothionein were grown in a solution containing 24x the dose of mercury which would kill non-resistant bacteria, they were able to remove more than 80% of it from the solution in five days.