Word: gutting
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This effect of the environment in the gut on the normal flora is readily recognized. For example, when breast feeding is replaced by solid food the character of the stool changes dramatically, as lactic acid bacteria (which produce sweet-smelling products) are replaced by E. coli and other foul organisms. Early in this century Mechnikov romantically hoped to promote longevity by supplying lactic acid bacteria, in the form of yogurt, to displace the presumably toxic foul organisms. The experiments were a dismal failure, but the commerical success is still seen...
...particular, it is known that bacteria can take up naked DNA from solution; and, in fact, transfer of DNA between two strains of pneumococcus has been demonstrated in the animal body. Moreover, bacteria in the gut are constantly exposed to fragments of host DNA that are released as the cells lining the gut die, and bacteria growing in carcasses have a veritable feast of DNA. The efficiency of such uptake of mammalian DNA by bacteria is undoubtedly very low. However, because of the extraordinarily large scale of the exposure in nature, recombinants of this general class must have been formed...
...consider the probability that an inadvertently produced harmful organism might cause a laboratory infection, and let us assume the worst case: an E.coli strain producing a potent toxin absorbable from the gut, such a botulinus toxin. Such a strain would indeed present a real danger of laboratory infection. But there are a number of reasons to expect this danger to be less than that with the pathogens that are handled every day by medical bacteriologists...
...under natural conditions (interpreted by the committee as residual viability after 24 hours). Just as infection can be dramatically cured by a bacteriostatic antibiotic, such as chloramphenicol, as well as by a bactericidal one, such as penicillin, so the inability of an EK2 strain to multiply in the gut would be sufficient to ensure its rapid disappearance, even if it did not rapidly commit suicide. The important question, requiring extensive investigation, is not the rate of suicide of the EK2 strain but the chance of transfer of its plasmid to a better adapted strain, before disappearance of the EK2 host...
...risks thus seem very much smaller than the public has been led to believe. Nevertheless, it is important to keep all the probabilities low. For example, even if a toxin-producing strain could survive only very briefly in the gut, a large enough dose might meanwhile cause disease. Hence a major benefit from the current discussion could be the requirement that those working in this area learn and use the standard techniques of medical microbiology, at least until we have acquired much more experience...