Reference no: EM133394051
1.A patient is in the hospital being treated for a lower GI infection caused by a pathogenic strain of Escherichia. coli. The strain of E. coli that the patient is infected with is resistant to the antibiotic chloramphenicol. The physician chooses to treat the patient with the antibiotic gentamycin. The E. coli are killed by the gentamycin. As a result of the death of the E. coli, DNA from the E. coli is released into the intestine of the patient. Shortly thereafter, a few Shigella cells enter the patient's intestine (probably through contaminated water). The Shigella that enters the patient's intestine carries the gene for streptomycin resistance. The Shigella that passes out of the intestine in the feces is resistant to both streptomycin and chloramphenicol. What is the most likely method of horizontal gene transfer taking place here? Justify your answer.
2. Escherichia coli O157H7 is a bacterial strain that has only been around for about 20 years. This strain of E.coli is responsible for a type of lower GI infection that can be very severe in some people (particularly the very young, the elderly, or the immunocompromised.) What makes this strain particularly nasty is that it has the ability to produce a toxin called a Shiga toxin. This toxin is very similar to toxins produced by many types of Shigella bacteria. The toxin is coded for stx genes which are carried by lysogenic bacteriophages. Based on this information, how did E. coli O157H7 acquire the genetic information to produce the Shiga toxin? Be specific in your answer.
3. In your opinion, is it usually more advantageous for a bacterium to obtain new genetic information by conjugation or by spontaneous mutation? Justify your answer.
4. In an effort to reduce the number of bacteria in bagged salads, some manufacturers are spraying the salad with bacteriophage.
A. Specifically, how does this aid in reducing the number of bacteria in the bagged salads?
B. Some microbiologists are concerned with this practice. Thinking about horizontal gene transfer, propose a reason for the concern.