In a message dated 2/13/01 7:36:06 PM, [log in to unmask] writes:
<< Jim Diamond, MD, posted the following to the Sierra Club Biotech Forum
listserv on Feb. 8.--Tom Mathews
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In answer to my post yesterday about Klebsiella planticola, Robert
Mann (in New Zealand) has sent the following. He says "I compiled this piece
on the Klebsiella experiment in full consultation with Dr Ingham, to give to
our Royal Commission. I am not aware of any disputes about this account."
I think this is the version to print out and share with your friends.
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Klebsiella planticola, a common soil bacterium, was genetically
engineered by a German research institute to make ethanol for industrial
purposes. The inventors had planned a recycling system: farmers would give
them agricultural slash, which would be used for the bacterial
fermentation; the resulting ethanol would be separated out, and the sludge
could be given back to the farmers to spread on their fields as fertilizer.
It all sounded very good for the environment, but how much soil ecology
impinged on the planning is unclear.
Dr Elaine Ingham of Oregon State University and her graduate
student M.T. Holmes discovered to their alarm that soils containing the
engineered organism killed wheat seedlings, most likely through alcohol
production in the root system, which kills roots at very low
concentrations. Mycorrhizal fungi were also killed.
Had the engineered sludges been returned to farmers, it would have
drastically degraded their soil, rendering them unable to grow many or all
plants. Since K. planticola is a ubiquitous organism, found in the root
systems of plants all over the world, the GM mutant could have spread and
made ALL soil unable to support crops! Microorganisms are easily spread on
surfaces of insects, on the feet of birds, on people's feet, etc; this
engineered bacterium could have spread world-wide quite rapidly.
Luckily Dr. Ingham and her student did the work before
commercialization and were able to warn the company, who didn't
commercialize it. The references are:
Holmes T M. and E.R. Ingham (1999) Ecological effects of genetically
engineered Klebsiella planticola released into agricultural soil with
varying clay content. Appl. Soil Ecol. 3 394-399;
Holmes T.M. and Ingham E.R. The effects of genetically engineered
microorganisms on soil foodwebs. in: Supplement to Bulletin of Ecological
Soc. Of America 75/2, Abs of the 79th Annual ESA Meeting: Science and
Public Policy?, Knoxville, TN, 7-11 August, 1994.
The story really shows the awesome power of genetic engineering, the
multidisciplinary nature of the review it requires, and the folly of
releasing GM microbes before very extensive contained studies.
This is a very good example of how slight changes in a highly evolved
bacterium can greatly change its ecological significance. Klebsiella spp
have adapted to many different niches; some are also not-too-virulent human
pathogens. Klebsiella pneumoniae rarely causes human disease but is a
common cause of aspiration pneumonia in alcoholics (i.e. a leading cause
of a somewhat rare condition). We know that small changes in bacteria or
viruses often tip the delicate balance between a pathogen and host and
result in large-scale outbreaks of disease. Many "new" diseases have
occurred, like syphilis in the 15th century, when slightly changed microbes
suddenly cause epidemics. The 1919-20 influenza pandemic, which killed
about 20 million - more than the Great War it closely followed - was
caused by a simple mutation in a virus.
>>
Although I don't recommend performing them (except in highly contained
environments if at all), two experiments (or theoretical outcomes) came to
mind as I read of this narrow escape from big trouble.
(1) If the engineered organism killed all of the plants and microorganisms
on which it fed, how would it survive? Would some precarious balance
develop, between killing its food and leaving some of it alive? (I'll not
speculate on what would happen to the rest of us, in the meantime, if this
were a global experiment.) Perhaps what I'm getting at, is, "Is this
engineered microorganism well adapted to survive in the competitive natural
world? What sort of tests could establish that adaptation? Or maybe even
more to the point, can one make such an engineered organism permanently
unable to make its way in nature, or to pass on its new trait to those that
are able to survive on their own?"
(2) Since plants seem to be very good at developing (or finding) resistance
genes that nullify chemical herbicides of all kinds, and microorganisms seem
to be very good at developing (or finding) genes that circumvent disease
resistance genes in plants, I wonder if resistance to the product of this
engineered Klebsiella might also develop or be found to be already present in
some species? [This question seems to have been pretty well answered from a
practical point of view by the experiments listed in today's email from Katie
Monson, so maybe it is irrelevant. But I'm still curious about the
possibility, although I don't know whether such an experiment would be worth
the trouble and expense.]
I'm well out of my depth in these speculations; maybe someone with more
knowledge than I can comment on them.
Don Duvick