Date: Fri, 7 Mar 1997
From: rwolfson@concentric.net (Richard Wolfson)
Subject: Joe's newsletter, Vol 2, #4

Here is the most recent issue of Dr. Joe Cummins's newsletter. This issue is somewhat technical. It discusses the effect of antibiotic resistant genes, which are inserted in many genetically engineered foods. Dr. Cummins describes various means by which these antibiotic resistant genes can get loose in the environment and lead to antibiotic resistant bacteria and diseases that could lead to epidemics and extensive damage to health.

Gene Tinkering Blues Vol. 2, Issue 4, February 1997 - "Death and Transfiguration"
Genetically engineered crop plants contain genes for antibiotic resistance. Such genes are used early in the selection of genetically engineered cells to be regenerated into mature crop plants. Though used in a fleeting manner very briefly early in the engineering process, the antibiotic tolerance genes are present as 'marker' genes in each cell of the crop. Such genes can be transferred to pathogenic bacteria in the guts of animals feeding on the crops or in the soil. Bacteria exhibit a form of interaction after death that has been called 'death and transfiguration.' In death and transfiguration, living bacteria scavenge genes from dead ones. Bacteria also spread genes by mating and some bacteria can mate with widely different species of bacteria.

The noteworthy concern about antibiotic tolerance is that by flooding the environment with antibiotic tolerance genes the usefulness of antibiotics will disappear. Antibiotic tolerance genes frequently have the ability to act on entire classes of antibiotics so that restricting some antibiotics to medical application is not necessarily an effective strategy. By overuse of antibiotics and spread of resistance genes, diseases such as tuberculosis and cholera have begun to produce epidemics of disease that have no effective treatment other than expensive isolation and quarantine procedures.

Clearly resistance genes can be transferred from bacteria that do not cause disease to those that cause epidemics in the digestive system of animals. Resistance genes have been transferred from resistant to sensitive bacteria on the surface of towels used to clean the teats of cattle with mastitis, on the surface of meat cutting boards and in the feces of pigs. Resistance genes in crop plants are bound to be transferred from the crops to sensitive bacteria in the gut, feces or soil. Nevertheless, 'experts' from the biotechnology industry argue that such transfers are not significant.

There is a technical problem that renders the direct detection of resistance genes in transfers between antibiotic sensitive and resistant bacteria technically challenging. Many of the bacteria that do not cause disease are tough soil bacteria that have thick protective envelopes that prevent penetration of antibiotics. When samples from soil, feces or digestive system are analyzed numerous colonies grow on antibiotic containing media, but these colonies are from nonpathogenic bacteria with thick selective walls, not from the tolerance genes that make pathogens resistant to antibiotics. Here-to-fore, experiments have not been done that would detect transfer of resistance genes from crops to pathogenic bacteria. However, such experiments are possible using a technique called polymerase chain reaction (PCR) in genetic fingerprinting.

Many pathogenic bacteria mate with other bacteria but do not take up genes from the media (transformation) unless environmental conditions are manipulated such as by adding calcium ions and natural chemicals that alter bacterial permeability. Other bacteria take up genes during growth periods called competence. Some bacteria are called 'promiscuous' because they can mate with virtually any bacterium and transfer antibiotic resistance during mating. In the ecosystem of the gut, those bacteria that easily pickup and transfer resistance genes are mixed with pathogens who must submit to the promiscuous mater.

Antibiotic resistant disease bacteria are beginning to overwhelm the public health control that was achieved nearly sixty years ago after antibiotics were discovered. Antibiotic control is disappearing because antibiotics are over used. Antibiotics are used extensively in animal production to enhance weight gain, in fish farming to prevent disease spread, and in human disease treatment. The human diseases with growing demand for antibiotics are those that compromise the immune system. These diseases include HIV, cancer treatment, organ transplant and treatment of autoimmune disease such as Lupus or arthritis. Putting antibiotic tolerance genes into crops will accelerate the growing loss in usefulness of antibiotics that will cause growing epidemics of disease.

Genetically engineered microbes (GEMS) have not yet been extensively released to the environment, but it is well established that GEMS are carried out of research laboratories on the laboratory coats of investigators. Even though such releases release hundreds of billions of microbes on each coat, such releases are minute when compared with the microbes populating a release to soil or as a dietary supplement. GEMS being prepared for release include microbes added to soil to enhance crop yield, microbes for frost protection, microbes for remediating polluted soil and various GEMS for food supplements and beverages including beer.

GEMS should not be released to the environment if they contain genes for antibiotic tolerance. As a general principle, genetic engineering design should be directed towards minimizing intrinsic traits of microbes that allow them to transfer genetic information to other microorganisms. However, that principle may conflict fundamentally with the genetic basis of the organism themselves.

References:

6 Special Issues
'Death and transfiguration among bacteria' N.Higgins TIBS 17,207,1992
'Clean white coats spread mutant microbes' New Scientist 21 March 1992
'R-Plasmid transfer in a patient with a mixed infection' Epidemiol.Infect. 112,247,1994
'Transfer of Multiple Drug Resistance Plasmids' Applied and Environmental Microbiology 60,4015,1994.
'Natural Genetic Transformation in the Environment' Microbial Reviews 58,563,1994

Prof. Joe Cummins
Professor Emeritus of Genetics,
University of Western Ontario

Richard Wolfson, PhD
Campaign to Ban Genetically Engineered Food
Natural Law Party
500 Wilbrod Street
Ottawa, ON Canada K1N 6N2
Tel. 613-565-8517 Fax. 613-565-6546
E-Mail: rwolfson@concentric.net

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