|
 
|
Study Examines Bacteria Reducing
Unwanted Chemicals in Soils
By Steve Olson
California Agricultural Technology Institute
Posted on
Friday, November 4, 2011 |
Microbiologists at Fresno
State are searching for a two-for-one bacterial bargain
that will help the natural environment recover more
quickly from chemical contamination of the soil.
Photos and Slideshow by JoAnne
Green
Dr. Alice Wright and Dr.
Mamta Rawat, both biology professors, recently completed
a faculty-student study of bacteria capable of
simultaneously detoxifying mercury and 2, 4-D, two
chemicals that have accumulated to higher-than-desirable
levels in some California soils.
Mercury is a naturally
occurring metal but has been found concentrated in soils
adjacent to mining operations. It was mined and used
extensively in both the Coast and Sierra Nevada mountain
ranges to purify ore deposits during gold-mining
operations.
“There is a lot of
concern now about [mine] sites that may be contaminated
with pollutants,” Rawat said. “Many old mercury mines
along California’s Coast Range have been closed, but
leftovers can seep out in concentrated amounts.”
If mercury leaches into
groundwater and eventually is ingested by humans, it can
cause an assortment of adverse reactions, affecting
major organs and the nervous system.
The phrase “mad as a
hatter” is thought to explain the odd behavior of
19th-century hatmakers who used mercury in their craft,
Rawat noted. Their symptoms included dementia,
moodiness, loss of coordination and shaking.
According to Wright, some
bacteria can reduce organic mercury into an inorganic
form that is more volatile but less toxic.
2, 4-D (2,
4-dichlorophenoxy acetic acid) is a widely-used
herbicide that some microbes are able to break down in
the soil, changing it to carbon dioxide and water.
However, health problems can arise when people are
exposed to concentrated amounts of 2, 4-D. Acute
symptoms include weakness and problems of the eyes,
skin, and mouth.
“Many bacteria are known
to degrade 2, 4-D, and likewise, others are known to
detoxify mercury,” Rawat said.
This study examined the
potential of selected microorganisms to detoxify soils
co-contaminated with mercury and 2, 4-D.
The study focused on two bacterial species (Cupriavidus
necator and Arthrobacter fluorenscens)
commonly found in soil.
Multiple tests using
different concentrations of mercury, 2, 4-D, and the
bacteria were conducted. Results were encouraging, but
not optimal, Wright reported.
“Although bacterial
growth was slowed when both toxins were added to the
soil, the combined toxins were toxic at lower
concentrations than the two toxins alone. So
comprehensively it was a positive result. The bacteria
will detoxify the metal and the organic pesticide at the
same time,” Rawat said.
The study also has
provided new information about how certain bacterial
genes are expressed when both pesticides and metals are
present during metabolism. The results have been
presented to the California State University Program for
Education and Research in Biotechnology and Central
California Research Symposium as well as the national
Society for the Advancement of Chicanos and Native
Americans in Science, Wright said.
Additional research
is warranted when funding is available, Wright said. The
project was conducted with partial financial support
from the California State University Agricultural
Research Institute, the U.S.
Department of Agriculture and
Environmental Protection Agency, and Dow Agrosciences.
Collaborating with Wright
and Rawat in the work were five Fresno State students
who have gained experience working with contaminants at
the molecular level.
“We had very talented and
hardworking students work on the project, and after this
work they have gone on to do great things,” Wright said.
Michelle Davison is
attending graduate school at Stanford University; Yaw
Anane works at an east coast biotechnology company;
Leslie Dominguez works at the Dried Fruit Association;
Chantale Johnson is a manager at Food Safety; and Denise
Lopez is the head of education for the Tulare County
Public Health Department.
For more
information on this study, contact Wright at
awright@csufresno.edu.
(Source: California Agricultural Technology Institute's
press release, Nov. 4, 2011
)
Celebrating National Ag Day
World
Ag Expo Celebrates 45 Years of
Excellence
Click Here for More Ag News
Click
Here for Main Page of Farms
&
Orchards
Have an
Awesome Day and Experience in
Clovis and Central California!
Clovis is what every
small town aspires to be
when it grows up!SM
|
Please click on +1
Google button below to like this page.
|
|
Share
