3 
Both tables could be interpreted as suggesting that the 
K-12 strain is not overwhelmingly debilitated by the insertion 
of "foreign" DNA and that in some environments it might survive 
long enough to transfer the inserted DNA to other bacteria. How- 
ever, these results must be seen as inconclusive in part because 
they have not been published and analyzed formally, even by those 
who carried out the experiments, and in part, because they have 
not been analyzed in conjunction with other findings on survival. 
In particular, they have not been compared to the findings of 
Levy and Marshall that "survival studies in the mouse intestinal 
tract may not simulate or predict results in that of the human," 
and that plasmids can increase survival of a debilitated strain 
of L.coli in a yet undefined way. (Levy and Marshall observed 
survival of the debilitated strain of E.coli, % 1776 carrying 
the plasmid pBR322 for a mean time of 82 hours in humans.)* 
10. Will recombinant DNA be transmitted from E.coli K-12 to other 
organisms? 
The data of Smith, Anderson, Curtiss, and Hamer cited in the 
discussion following this heading were available before the re- 
vision of the guidelines in 1978. (It should be noted that Curtiss 
does not support the weakening of the guidelines that is now con- 
templated. **) 
Two sources of data obtained since the revision of the guidelines 
in 1978 are also cited: 
i) S.Levy et al. "Survival of E.coli Host-Vector Systems in 
the Mammalian Intestinal Tract," an unpublished paper contained 
in "Background Documents on E.coli K12/P1 Recommendation," part 15. 
This experiment is one in a series conducted by Levy under 
contract to NIH as a part of the NIH risk assessment program. The 
paper reports on a continuation of the work described above, under 
q.9. Levy and colleagues observed the plasmid transfer and survival 
of the K-12 strain of E.coli and of a debilitated or "EK2" strain 
known as "9(1776." in humans and mice. Only one aspect of their results 
is mentioned in the discussion under this subheading, namely, that 
no evidence was found of transfer of the plasmid pBR322 carried by 
the L.coli strains. However, the comment does not mention that these 
observations are incomplete. Only transfer to aerobic bacteria was 
measured. Measurement of transfer to anaerobic bacteria (a more 
difficult operation to carry out) was not attempted. 
In addition, the comment does not draw attention to the most 
surprising aspect of Levy's work, mentioned above, namely, that 
the insertion of the plasmid pBR322"appears to enhance the ability of its 
debilitated E.coli host to survive in the intestinal environment 
of the human but not the mouse." It should be noted that some 
I 
S.Levy and B. Marshall, "Survival of E.coli Host-Vector Systems in The 
Human Intestinal Tract," Recombinant DNA Technical Bulletin 2 (July 1979). 
** R. Curtiss to W.Gartland, 11 May 1979; R. Curtiss to D .Fredrickson , 
4 October 1979. (Letters in sections 3 and 16 of the "Background 
Documents . " ) 
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