Throughout the world heavy metal pollution is considered a serious issue. Pakistan is also facing problem of industrial, municipal, vehicular and air pollution. While some of the heavy metals play a vital role in biological systems there are others which are purely toxic with no known cellular role. Excessive levels of even the most essential metals can be highly toxic to the organism. Essential heavy metal ions present a dual challenge as these are useful but can also be lethal. Genetic basis of heavy metal tolerance in bacteria has been studied by researchers and interesting facts are found which can lead towards the better use of these naturally occurring mechanisms for the betterment of environment for all the living organisms.
