Please show all your work step by step! Thanks! 3. You are given three stock cul
ID: 269005 • Letter: P
Question
Please show all your work step by step! Thanks!
3. You are given three stock cultures - Pseudomonas at a concentration of 3.8 x 104 CFU/ml, Bacillus at a concentration of 2.6 x 104 CFU/ml, and Staphylococcus at a concentration of 1.8 x 104 CFU/ml. You have been asked to make 30 ml of a single mixed culture with a final concentration of 3 x 102 CFU/ml of Pseudomonas, 7 x 102 CFU/ml of Bacillus, and 70 CFU/ml of Staphylococcus. In the space below, show me how you would make this mixture. [3 points If you plate 0.3 ml of the mixture on a TSA plate, how many colonies each of Pseudomonas, Staphylococcus, and Bacillus would you expect to get? Don't worry if this results in an uncountable plate. [3 points] a) b) If you plate 0.6 ml of the mixed culture above on a MacConkey agar plate, how many total colonies would you expect to get? [6 points]Explanation / Answer
Answer:
3) Based on the given information:
Total final volume required = 30 ml
Final Concentration required:
Calculations:
We will first determine the fold dilution for each species using the formula:
Fold dilution = Initial Concentration / Final Concentration
Volume of each culture that needs to be added to 30 ml final culture to get the desired concentration can be determined as below:
Volume of culture required = Final volume / Fold Dilution
So to get the desired concentration add 237ul Pseudomonas culture + 808ul Bacillus culture + 117ul Staphylococcus culture to 28.838ml media to get single mixed culture.
a) 0.3ml of the mixture on a TSA plate, number of colonies expected are as below:
b) 0.6ml of the mixture on a MacConkey agar plate, total number of colonies expected are as below:
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