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

Nowadays, due to industrialization and extraction of
natural resources, soil and water pollution is one of the major global
concerns. During the recent era of environmental protection, the use of
microorganisms for the recovery of heavy metals from soil, sediments and water
as well as employment of plants for landfill applications has generated growing
attention. The role of microorganisms and plants in biotransformation of heavy
metals into nontoxic forms is well-documented, and understanding the molecular
mechanism of metal accumulation has numerous biotechnological implications for
bioremediation of metal-contaminated sites. The food and water we consume are
often contaminated with a range of chemicals and heavy metals, such as gold,
copper, nickel, zinc, lead, cadmium, arsenic, chromium, and mercury that are
associated with numerous diseases. Human activities like metalliferous mining
and smelting, agriculture, waste disposal or industry discharge these metals
which can produce harmful effects on human health when they are taken up in
amounts that cannot be processed by the organism.  Many studies have demonstrated that microbes
have the ability to remove heavy metals from contaminated soils. Among others
some of the microorganisms that play great role in bioremediation of heavy
metals are Pseudomonas spp. Alcaligenes spp.,  Arthrobacter spp., Bacillus spp.,
Corynebacterium spp., Flavobacterium spp., Azotobacter spp., Rhodococcus spp. Mycobacterium
spp., Nocardia spp., Methosinussp., Methanogens,  Aspergilusniger,  Pleurotusostreatus, Rhizopusarrhizus,
Stereumhirsutum, Phormidiumvalderium and
Ganodermaapplantus. The encouraging evidence as to
the usefulness of microorganisms and their constituents for the
remediation of heavy metals from contaminated soils is reviewed in this
article.