SBRP-funded remediation research covers the spectrum of technologies being developed for the cleanup of groundwater, sediments, soil and other environmental media contaminated with hazardous substances. With primary prevention as the goal, researchers are developing innovative biological, chemical and physical methods that effectively reduce the amount and toxicity of hazardous wastes. Remediation research also includes development of new and improved methods of hazardous waste containment, recovery and separation. This broad area of research includes laboratory and bench studies, and applied field research once a technology has reached an advanced level.

Biotechnology Overview from the EPA's Web site
In the broadest sense, biotechnology is the application of living organisms or parts of organisms to improve, modify, or produce products or processes for specific uses. Biotechnology has been around for centuries. Microorganisms have long been used in the production of bread, yogurt, alcoholic beverages, antibiotics, and enzymes. In the past few decades, techniques in biotechnology have expanded to include genetic engineering. With this technology scientists can move genetic material of one organism into another. The genetic insert can allow the organism to express desired characteristics. For example, insertion of a piece of DNA from the bacterium Bacillus thuringiensis (Bt) into the DNA of corn plants can enable these plants plants and their progeny to produce a Bt protein which confers resistance to particular insect pests. A wide variety of organisms can now be routinely altered in such ways, and the diversity of traits that can be conferred is nearly limitless. EPA is currently responsible for regulating a subset of products developed using biotechnology.

The Biotechnology Team located in EPA's Office of Science Coordination and Policy (OSCP) coordinates scientific, technical, and policy development activities within the Office of Prevention, Pesticides, and Toxic Substances (OPPTS). The OSCP Biotechnology Team is also a focal point for coordination with other Federal agencies on any issues involving biotechnology, including international activities.

Under the Toxic Substances Control Act (TSCA) , EPA tracks all chemical substances or mixtures of chemical substances produced or imported into the United States. Genetically engineered microorganisms meet the TSCA legal definition of a "mixture" of chemical substances and are therefore regulated under this act. TSCA is administered by the Office of Pollution, Prevention, and Toxics (OPPT).

National Agricultural Library list of links
http://www.nal.usda.gov/bic/Biorem/biorem.htm

The Bioremediation Field Initiative
http://www.epa.gov/ORD/WebPubs/biorem/reilly.pdf

The Bioremediation Field Initiative was established in 1990 to expand the nation’s field experience in bioremediation technologies. The Initiative’s objectives are to more fully document the performance of full-scale applications of bioremediation; provide technical assistance to regional and state site managers; and provide information on treatability studies, design, and operation of bioremediation projects. The Initiative currently is performing field evaluations of bioremediation at eight other hazardous waste sites: Libby Ground Water Superfund site, Libby, MT; Park City Pipeline, Park City, KS; Bendix Corporation/Allied Automotive Superfund site, St. Joseph, MI; West KL Avenue Landfill Superfund site, Kalamazoo, MI; Eielson Air Force Base Superfund site, Fairbanks, AK; Hill Air Force Base Superfund site, Salt Lake City, UT; Escambia Wood Preserving Site, Brookhaven, MS; and Public Service Company, Denver, CO. To obtain profiles on these additional sites or to be added to the Initiative’s mailing list, call 513-569-7562. For further information on the Bioremediation Field Initiative, contact Fran Kremer, Coordinator, bioremediation Field Initiative, U.S. EPA, Office of Research and Development, 26 West Martin Luther King Drive, Cincinnati, OH 45268; or Michael Forlini, U.S. EPA, Technology Innovation Office, Office of Solid Waste and Emergency Response, 401 M Street, SW., Washington, DC 20460.

Plant Biology
Ji-Ming Gong, David A. Lee, and Julian I. Schroeder * (2003). "Long-distance root-to-shoot transport of phytochelatins and cadmium in Arabidopsis." PNAS 100(17): 10118-10123.
http://www.pnas.org/cgi/content/abstract/1734072100v1

SBRP Research Brief 110: Resistance to Heavy Metals - a Possible Tool for
Phytoremediation (focused on Julian Schroeder's work)

Several species of plants are able to survive in environments contaminated
with high concentrations of metals. An understanding of the mechanisms that
enable these species to accumulate and tolerate heavy metals could lead to
cost effective approaches for the remediation of heavy metal-laden soils and
waters. Dr. Julian Schroeder at the University of California, San Diego
(UCSD) is part of an SBRP-funded research project designed to identify,
isolate and characterize genes and physiological mechanisms that result in
heavy metal accumulation and detoxification by plants.

In general, toxic ions are removed from eukaryotic cells by chelation and
sequestration. Following exposure to metals, in plants, fungi and worms,
the enzyme phytochelatin synthase (PCS) synthesizes the peptide
phytochelatin (PC) from glutathione. Phytochelatins can form complexes with
arsenic, cadmium, lead, and mercury, and these peptide-metal complexes are
transported into plant lysosomal vacuoles, effectively isolating the toxic
metals from various metal-sensitive enzymes in the plant cell cytoplasm.
Often, metal concentrations can be significantly higher in plant roots than
in the shoots or leaves. Prior to this research, it was hypothesized that
phytochelatins function mainly in detoxifying metals within the cells where
metals are taken up, and that phytochelatins cannot undergo long distance
transport in plants. Therefore, it was thought that targeted expression of
phytochelatin synthase genes to plant roots would cause sequestration of
heavy metals in roots. For phytoremediation purposes, it would be optimal
if the heavy metals were transported to the shoots and leaves before
sequestration into vacuoles because the aerial parts of the plant can be
easily harvested.

Dr. Shroeder's group is using transgenic plants to investigate questions
concerning the root-to-shoot transport of phytochelatin synthase,
phytochelatins and/or heavy metals. Starting with mutant Arabidopsis plants
(cad1-3) that do not produce detectable levels of phytochelatins, they
designed test systems to evaluate long-distance transport during heavy metal
detoxification. They cloned a wheat PCS gene (TaPCS1) and inserted it into
cad1-3 mutant plants, resulting in plants with TaPCS1 activity targeted in
either the roots only or alternatively in stems, rosette leaves and roots
(ectopic expression). Transgenic Arabidopsis (root-specific and ectopic),
wild type Arabidopsis and cad1-3 mutant plants were then exposed to cadmium,
mercury and arsenic . The Schroeder lab found that:
(1) both root-specific and ectopic transgenic expression of TaPCS1
suppressed the heavy metal sensitivity of cad1-3 mutant plants to arsenic,
mercury and cadmium.
(2) in plants expressing the phytochelatin synthase enzyme in roots only,
phytochelatins were detected in roots and interestingly also in rosette
leaves and stems.
(3) both root-specific and ectopic transgenic expression of TaPCS1 reduced
cadmium accumulation in roots - indicating that phytochelatin-dependent long
distance transport plays a role in maintenance of low cadmium levels in the
roots.
(4) both root-specific and ectopic transgenic expression of TaPCS1
significantly enhanced long distance cadmium transfer and accelerated
cadmium accumulation in stems and rosette leaves - much more cadmium was
transported from roots to shoots in transgenic plants compared to wild type
plants.

These findings demonstrate that root-to-shoot transport of phytochelatins
does occur and indicate that phytochelatins can provide an important
mechanism for regulating long-distance cadmium transport in Arabidopsis. To
follow-up on these findings, Dr. Schroeder is beginning additional studies
to determine which vascular transport pathways mediate long distance
phytochelatin transport (xylem or phloem), and to identify the molecular
mechanisms underlying vascular phytochelatin loading.

Various studies indicate that removal of heavy metals from soils by plants
would be one to two orders of magnitude less costly than excavation,
transport and burial. This work highlights the real possibility that
biological engineering could be used to produce transgenic plants to
maximize the uptake of heavy metals. Dr. Schroeder emphasizes that for
engineering of highly efficient heavy metal hyperaccumulator plants, several
processes and genes would likely need to be enhanced in parallel in plants.
As a first step, the rate-limiting genes and mechanisms need to be
characterized. Dr. Schroeder is working closely with the UCSD SBRP Outreach
Program to move these advances into practical applications at hazardous
waste sites in San Diego.

For More Information Contact:

Julian Schroeder, Ph.D.
Center for Molecular Genetics
University of California - San Diego
9500 Gilman Drive
La Jolla, CA 92093-0116
Phone: 858-534-7759
Fax: 858-534-7108
E-mail: julian@biomail.ucsd.edu

To learn more about this research, please refer to:
Gong, J.M., D. Lee, J.I. Schroeder. August, 2003. Long-distance
root-to-shoot transport of phytochelatins and cadmium in Arabidopsis.
Proceedings of the National Academy of Sciences of the United States of
America 100:10118-10123.

Lee, D.A., A. Chen and J.I. Schroeder. September, 2003. Ars1, an
Arabidopsis mutant exhibiting increased tolerance to arsenate and increased
phosphate uptake. Plant Journal. 35(5):637-646.

Thomine, S., F. Lelievre, E. Debarbieux, J.I. Schroeder and H.
Barbier-Brygoo. June, 2003. AtNRAMP3, a multispecific vacuolar metal
transporter involved in plant responses to iron deficiency. Plant Journal.
34(5):685-695.

The following shows a video from a general public science lecture in the lecture series "Science matters" on the subject: "Plant Genetics and the environment" held on June 9th 2001.
http://www-biology.ucsd.edu/labs/schroeder/

To learn more about the Superfund Basic Research Program web site, look us
up at: http://www-apps.niehs.nih.gov/sbrp

The Research Briefs are available on our webpage at the following address:
http://www-apps.niehs.nih.gov/sbrp/RB2000/RB.cfm