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escaped out of, say, a physical environment where it has been produced, 
what would the survival rate be there, and what kind of exchange may occur 
there that would then infect the environment at large, saying nothing about 
the potential for that organism to survive in the carrier inside the labora- 
tory, and that person taking it to the environment outside. That is both 
questions, and maybe you don't have all the answers now, but — 
DR. HELINSKI: Well, I can try to respond to your two points. Number 
one, when I made the analogy to things going right for the circuitry, I 
was talking about the machinery itself, the cell, and the analogy with the 
spacesh ip . 
DR. AHMED: The cell, right, okay. 
DR. HELINSKI: Now, it is quite clear that there are a lot of factors, 
anibiotic therapy or intestinal problems or what have you. But I would like 
to say to you on this point that the component probabilities, given this 
final factor of 10 -16 with best-case situations as far as what we know, and 
we know a lot about the transmissibility — 
DR. AHMED: That is in the intestinal tract, though? I just want to 
get that clear. 
DR. HELINSKI: In the intestinal tract, we know that that is not a 
best situation. That is to say that the conditions are considerably poorer 
in the intestinal tract for transmissibility than in the test tube under 
very good conditions. 
DR. AHMED: What about in the environment in general. Do you still 
maintain a 10 -16 ? 
DR. HELINSKI: There is little information on the soil. On the other 
hand, as Dr. Szybalski has emphasized earlier today, E. coli K-12 is not 
a soil organism. I can document to you observations carried out in labora- 
tories where the conditions in so_il are very threatening to the surviva- 
bility of E^ coli K-12. 
DR. AHMED: That may be true with E, coli K-12, but may be not true 
for other organisms. Don't you agree? I mean, there are a lot of anti- 
biotics in the soil. That is how you have a maintenance of microbial popu- 
lations . 
DR. HELINSKI: There are lots of wonderful organisms in the soil, but 
I am not so sure that is relevant. We are talking about the survivability 
o f E^ coli K-12. 
DR. AHMED: No, I don't really mean that. I am talking about something 
in general. I am trying to ask some general questions about when you talk 
about probability you mean in the context of EK12? 
DR. HELINSKI: That is what I was referring to. 
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