a student inoculated E.coli into 2 test tubes containing the same sterile liquid
ID: 9575 • Letter: A
Question
a student inoculated E.coli into 2 test tubes containing the same sterile liquid medium except the first test tube also contains one drop of an anti microbial chemical...after 4 hours of incubation the first tube remains clear while the second tube becomes cloudy with bacteria...you want to know the mechanism by which the antimicrobial worked ...briefly describe an experiment that would determine if it worked by a bacteriolytic mechanism, bacteriostatic and bactericidal mechanism
im stuck!! i dont understand how would i be able to determine...if i grow it in a culture MBC testit would tell me if its bacteriostatic but what about the rest??
Explanation / Answer
The first tube in the experiment has remained clear while the second tube has become cloudy. As you want to find out the action of an anti-microbial chemical added to the first tube, you can perform the following experiment. Take the first tube with the chemical. Take a sample from the tube and spread on an agar plate and incubate for 24 hours. After 24 hours observe for growth on the culture plate. If growth is seen, the anti-microbial chemical is bacteriostatic. If no growth is seen, the anti-microbial chemical can be either bactericidal or bacteriolytic. ------------------------- To check whether the anti-microbial chemical acts as a bactericidal or bacteriolytic agent, we check for the presence of DNA/RNA. This can be done by exposing the test tube to ultraviolet light at 260nm. If the agent is bactericidal, you will get a OD reading. If the agent is bacteriolytic, the OD reading will be absent/ very low.Related Questions
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