21 February
2008:
Australian scientist have discovered an amazing
arsenic-eating super-bug that can chomp its way through the deadly
leftovers of a century of mining and farming to help clean up our
landscape. The microbe may
also offer a low-cost way to help save tens of millions of people
from the worst poisoning event on the planet.
The
super-bug was identified after screening thousands of samples of
microbes from soils heavily contaminated with poisonous arsenic
which was once used to control parasites on sheep and cattle. At
these sites arsenic is usually present in the highly toxic form
arsenite, or as the less toxic arsenate. It is the
highly toxic arsenite which is most difficult to remediate.
“It was a case of serendipity,” says Professor
Megh Mallavarapu of the CRC for Contamination Assessment and
Remediation of the Environment and the University of South
Australia.
“We’d been looking for over a year at microbes
that tolerate arsenic and DDT – and this one popped up. It
takes in the highly toxic arsenite, and oxidises it to the much
less dangerous arsenate form, which can easily be immobilised other
methods.
“There are so many microbes in the soil we might
easily have missed it – but luckily we
didn’t.”
The
bug holds hope of developing an efficient biological method for
cleaning up the hundreds of thousands of arsenic stock dip sites in
Australia, New Zealand, Argentina and other countries, places where
arsenic-treated timber posts have been made or used, sites of old
railway lines, as well as old gold-mining regions where arsenic
flushes out of tailings dumps into surface and groundwater, posing
a risk to those who drink it.
The
microbe could also be used to cleanse household drinking water in
Bangladesh, India, China and South East Asia where an estimated 100
million people face daily poisoning from arsenic in their well
water, Professor Mallavarapu says.
Besides being known to cause cancer of the skin, lung,
bladder, kidney, liver and uterus, arsenic is also linked to
several skin diseases, nerve disorders, diabetes, lung disease,
heart disease, suspected birth defects, liver and blood disorders,
says CRC CARE Managing Director Professor Ravi Naidu.
“This is a truly momentous discovery by Professor
Mallavarapu and his team, as it addresses one of the most
intractable contamination problems facing almost all
societies,” he says. ”They are to be congratulated on
this important advance for Australian remediation
science.”
“The beauty of this organism is that it performs the
breakdown of toxic arsenite very efficiently,” says Professor
Mallavarapu . “We isolated hundreds of arsenic-tolerant
species - but this one breaks down the most toxic form of arsenic
in a very efficient manner.”
“The microbe is completely harmless to humans,
animals and the environment in other respects. It also tolerates
other toxins such as cadmium and lead.”
“We can cultivate these microbes on a large scale and
then put them into the contaminated soil or water. This would be an
efficient and low-cost way to make them much safer for people
living nearby, growing crops on contaminated land or drinking water
that passes through it.”
The
team is currently engaged in more detailed genetic screening to see
if they can assess the potential to develop even more efficient
pollution-busting organisms. A valuable outcome would be tools that
provide a rapid test for the presence of arsenic in soil or
water.
This would greatly accelerate the process of finding out
which soils and groundwaters are most in need of remediation, and
checking drinking water supplies to ensure they are safe, Professor
Mallavarapu says.
More information:
Prof. Megh Mallavarapu, CRC CARE & UniSA, 08 8302 5044
or 0411 035 757
Professor Ravi Naidu, CRC CARE, 08 8302 5041 or 0407 720
257
Peter Martin, CRC CARE communication, ph 08 8302 3933 or
0429 779 228
peter.martin@crccare.com
www.crccare.com
