Detection of heavy metal ion resistance genes in lead-resistant bacteria

Many agricultural and industrial practices have led to environmental pollution by heavy metal ions. Metals, such as zinc, cobalt, cadmium, nickel, copper and chromium, are used for several industrial applications, such as production of steel and other alloys, galvanisation of iron, electroplating, manufacture of batteries, TV tubes and pigments. Copper has been used for a number of years as an active ingredient of bactericides and fungicides and as a growth enhancer of pigs. Mercury is a by-product of burning coal and petroleum products, and it is also used in household and hospital disinfectant. Contamination of soil by lead occurs following the use of lead arsenate insecticides. High levels of lead in wastewaters may originate from combustion of leaded gasoline, coal burning or metal smelting. Mining and leaching from natural deposits also contribute to environmental contamination. A number of sites contaminated by heavy metals around the world are associated with human activities, such as discharge of wastes into natural waterways, various metallurgical industries, accidental spills or mining [1–8].