Washington, Aug 12 (IANS): Scientists have engineered bugs that are not only resistant to high levels of mercury but can also mop up spills of the toxic substance.

Thousands of tonnes of mercury, discharged by industries every year, enter the food chain as toxic methyl mercury and ends up in the fish that we eat.

The mercury-resistant bugs, developed by researchers, 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, reports the journal BMC Biotechnology.

"This method not only would allow us to clean up mercury spills from the environment but the high accumulation of mercury within the transgenic bacteria also provides the possibility of recycling it for further industrial applications," said Oscar N. Ruiz of the Inter-American University, Puerto Rico, who led the research.

The bugs with metallothionein, grown in a solution containing 24 times the dose of mercury which would kill non-resistant bacteria, were able to remove over 80 percent of it from the solution in five days.

The metallothionein family of proteins regulates zinc and copper levels in blood, detoxify mercury and other harmful metals and regulate the development and function of the immune system, among others.

Common symptoms of mercury poisoning include itching, burning or pain, skin discoloration, swelling and shedding of skin.