Some fungi and bacteria can be used to extract metals from mine effluents
THREE teams of scientists at
the University of Delhi South
Campus have identified fungi,
algae and bacteria that are natural extractors of metals
washed out in mine effluents.
Sheela Srivastava, a microbial geneticist at the university, says these microorganisms can be exposed to the polluted water and left to gobble up
metals as they are wont to.
The metals can then be
extracted from the bugs using
powerful solvents like
hydrochloric acid. The technique works out to be cheap, she adds.
Srivastava's team has
identified bacteria of the
Pseudomonas family that can
accumulate both zinc and
copper. In trials at the Khetri
Copper Complex in Rajasthan,
they found that one strain of
Pseudomonas can remove
between 70 and 90 per cent of
the zinc and copper in the
effluents. Another strain can
remove zinc from low-grade
ores. Srivastava says whole
colonies of some bacteria that
accumulate copper turn blue in
presence of a copper-rich effluent.
The team is designing a bioreactor
to extract metals from mine effluents.
It says the bioreactor will be
economical, handy and reusable. The team is also
trying to understand the
genetic basis of the ability of
microorganisms to resist the
poisonous effects of metals.
R K Saxena, another
microbiologist at the university, and his colleagues have
discovered that certain fungi
like Trichoderma and Aspergillus can collect copper,
cobalt and nickel in their
thread-like bodies. Many of
these fungal strains have the
ability to degrade cellulose -
a major carbohydrate component of plants - and the scientists claim they can be
employed to break down
organic waste as well as clean up metals.
Microbiologist Rani
Gupta and her colleagues
have identified certain
strains of blue green algae -
Plectonema and 0scillatoria
- which can absorb zinc.
The algae photosynthesise
their food and so are cheap to
grow.
Bacteria (left) change colour after absorbing copper P Mangala Gowri and Purnima Anand are research the scholars at the University of Delhi South Campus.
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