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By inserting separate , successive sections of " V. cholerae " DNA into the DNA of other bacteria , such as " E. coli " that would not naturally produce the protein toxins , researchers have investigated the mechanisms by which " V. cholerae " responds to the changing chemical environments of the stomach , mucous layers , and intestinal wall .
 biology: E. coli
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Text: {0} 
Answer:
 biology: E. coli