Microbial Bioremediation of some Heavy Metals in Soils: An updated review

Abstract

Nowadays, due to industrialization and extraction ofnatural resources, soil and water pollution is one of the major globalconcerns. During the recent era of environmental protection, the use ofmicroorganisms for the recovery of heavy metals from soil, sediments and wateras well as employment of plants for landfill applications has generated growingattention. The role of microorganisms and plants in biotransformation of heavymetals into nontoxic forms is well-documented, and understanding the molecularmechanism of metal accumulation has numerous biotechnological implications forbioremediation of metal-contaminated sites. The food and water we consume areoften contaminated with a range of chemicals and heavy metals, such as gold,copper, nickel, zinc, lead, cadmium, arsenic, chromium, and mercury that areassociated with numerous diseases. Human activities like metalliferous miningand smelting, agriculture, waste disposal or industry discharge these metalswhich can produce harmful effects on human health when they are taken up inamounts that cannot be processed by the organism. Many studies have demonstrated that microbeshave the ability to remove heavy metals from contaminated soils. Among otherssome of the microorganisms that play great role in bioremediation of heavymetals are Pseudomonas spp. Alcaligenes spp., Arthrobacter spp., Bacillus spp.,Corynebacterium spp., Flavobacterium spp., Azotobacter spp., Rhodococcus spp. Mycobacteriumspp., Nocardia spp., Methosinussp., Methanogens, Aspergilusniger, Pleurotusostreatus, Rhizopusarrhizus,Stereumhirsutum, Phormidiumvalderium andGanodermaapplantus. The encouraging evidence as tothe usefulness of microorganisms and their constituents for theremediation of heavy metals from contaminated soils is reviewed in thisarticle.