1. A culture of E. coli was grown on suitable culture media; aliquots of the cul
ID: 19835 • Letter: 1
Question
1. A culture of E. coli was grown on suitable culture media; aliquots of the culture were serially diluted and spread plated aseptically on agar plate media at the times indicated in the table below. Upon overnight incubation at 37°C, colonies appeared and viable counts were colleted and displayed below.
Hours Viable Counts (CFU/mL)
0 2.00 x 107
1 2.10 x 107
2 2.30 x 107
3 3.25 x 107
4 6.60 x 107
5 1.40 x 108
6 2.92 x 108
7 6.10 x 108
8 1.10 x 109
9 1.23 x 109
10 1.30 x 109
Plot the data using Excel and indicate the growth phases observed and their length for this E. coli culture. Using the graph, interpolate the generation time (gt) for this culture.
Using the formulas, calculate the generation time for the E. coli culture.
Please show your work and all Excel printouts for credit.
2. In the laboratory, you decided to investigate the growth of Salmonella typhimurium in nutrient broth by using both viable cell counts and optical methods (spectrophotometry) simultaneously. Cultures of Salmonella were incubated in nutrient broth at 37°C and aliquots were serially diluted and spread plated on nutrient agar plates at indicated times. Simultaneously, the optical density of the culture was measured and indicated in the table below.
Time (hrs.)
0
0.5
1.0
1.5
2.0
2,5 3.0
3.5
4.0
Viable Counts (CFU/mL)
3.00 x 107
2.90 x 107
3.50 x 107
6.00 x 107
2.40 x 108
1.01 x 109 2.000
OD660nm
0.050 0.051 0.065 0.120 0.510
2.30 x 109 3.10 x 109 3.50 x 109
3.400 4.300 4.400
Explanation / Answer
If you are going to ask one of these questions, no one is going to answer it if you post 2 parts up especially when they are as long as this... When something is this long think about the person answering it, it takes ~5-10 mins to do each. Why would I spend 10-20 mins on this one problem without a guaranteed approval rating... People don't. It will be rare that you find someone who will take the time to answer it. As a suggestion, just post 1 at a time and post 2 questions in stead. Also it is against the rules to post more than 1 question in a problem
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