Question

Question 3: A group of scientists were interested to see if drug A had any effect on the growth of pathogenic S. aureus. They performed an experiment in triplicate with and without drug A. The experimental details are as follows: S. aureus was grown in two independent flasks containing 100 mL media overnight. In the morning, 1 mL of the media containing S. aureus was added to two independent flasks containing 100 mL media where one flask had drug A and the other had no drug. The growth profile of S. aureus was monitored by measuring the optical density at OD600. After six hours, the following ODs were obtained. OD without OD with drug A drug A. 0.5 0.6 0.55 0.45 0.65 0.55 Can you identify the issues with the experiment? Looking at the OD values, please discuss the result

Answer 1

Given, flasks containing experiment was done in 100 ml media with and without two independent drug A. OD with OD without drug & drug A 0.6 0.5 As the experiment is done in the same Cuvette and for both soux case, the solution is same. Hence, in both cases the optical path length u and molar absorbptivity && is same. 0:55 0.45 0.65 0.55 We know from Lambert - be from Lambert - Beer's law- Abs. on 00- Ecl where, (= concentration i. In case of the solution without drug A :- Abs. – ECL 0.6 = EXCL " Exl 0.5 In case of the solution withdrug A:- Abs. – Ec'h 0.5 = Ec'l « c'- 0 The ratio of concentration of with and pathogenic S. aureus without drug A – 0 – 1.2 - hence, the drug & reduced the concentration of pathogenic S. aureus by - (1.2-1) + 100% = 207. In another two experiments, the drug A reduced the concentration of pathogenic S. aurens by 22.1. and 187. Hence, the drug A reduced the concentration of pathogenic S. aureus on average = 20 +22 +18 = 20%