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BACKGROUND: There are currently few
satisfactory choices for the rectification of toxic
or radioactive metal contamination of soils. On a small
scale, contaminated areas may be restored by physical
removal of surface layers, followed by appropriate disposition
(usually remote burial) of the material and re-landscaping
to restore the site. On a large scale, this approach
is infeasible, and the alternative is to abandon the
land for a prolonged period or permanently, restricting
access or uses. The current invention offers a means
of safely and economically depleting soils of metal
contaminants through a bioremediation approach that
preserves the original structure of the land and eventually
restores its utility, even when many square miles are
involved.
DESCRIPTION: A cDNA encoding a novel
cation pump having broad specificity has been isolated
and characterized from a wheat root library. Clones
incorporating this ion uptake pump can be transferred
to species of plants having deep root systems and rapid
growth on a variety of soils. With the ion pump over-expressed
throughout the plant tissues, these transgenic plants
are capable of accumulating a variety of toxic metals
from the soil and concentrating them on leaf surfaces
or internally.
Metal ions targeted by this system include: cadmium, lead, zinc, nickel, antimony,
mercury, silver, tin, copper, cobalt, cesium, strontium, radium, uranium and
osmium. Beryllium and aluminum are not effectively transported by this system,
nor are metal ions existing as tightly-bound complexes. By a repetitive process
of extensive planting, harvesting and incineration of the contaminated biomass,
the metal toxicant in the soil can be reduced to acceptable levels.
ADVANTAGES: This method of bioremediation
is of particular use in removing heavy metals and
certain radioactive metals that could be associated
with industrial or nuclear mishap contamination of wide
areas. Bioremediation systems using plants
are often restricted to certain species -- this
approach allows the combining of the most suitable plant
for the task/environment with overexpression of the
high-capacity metal pump.
CASE NUMBER: 96-102
INQUIRIES TO: invent@ucsd.edu
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