Critical for controlling penicillin-resistant bacteria | Homework Helpers

Vancomycinis an antibiotic that has become critical for controlling penicillin-resistant bacteria. This large glycopeptide (molecularwt. = 1449) binds to cellwall precursors and interferes with peptidoglycansynthesis.

The polymyxinsare a group of antibiotics that are particularly effective as atopical antibiotic against skin infections. These largepolypeptides (molecular wt. = 1202) can disrupt some bacterialmembranesby binding preferentially tolipid Amolecules. In the experiments below, different prokaryoticcells were grown in broth cultures in the presence orabsence of anantibiotic (either vancomycin or polymixin). After 1 hour, cellswere rinsed, and the percent of bacteria that survived wasdetermined.
Graph Awas…       
              
                                       Bacillus                       E.Coli                            Methanoge n(archaea)
With Antibiotic—–     80%CellSurvival            20%CellSurvive               90%Cell Survive
Without Antibiotic—   100% CellSurvive            100%CellSurvive            100%Cell Survive

Graph B was…
                                             Bacillus                       E.Coli                            Methanoge n(archaea)
With Antibiotic—–    30% CellSurvival            80%CellSurvive               100%Cell Survive
Without Antibiotic—   100% CellSurvive            100%CellSurvive            100%Cell Survive

QUESTION IS:
Using the dataabove, predict which experiment (A or B) was done using vancomycin andwhich experiment was doneusing polymyxin, and explain yourrationale.

NOTE: Bacillushas a Gram (+) type envelope; E.coli has a Gram (-) type envelopeand

Methanobacteriumisan Archaea. (Hint: think about cell envelopestructure).