In the laboratory, you decided to investigate the growth of Salmonella typhimuri

Question

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 370C 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) viable Counts (CFU/mL) OD 660nm 3.00 x 10 0.050 2.90 x 107 0.5 0.051 1.0 3.50 x 10 0.065 6.00 x 10 0.120 2.0 2.40 x 10 0.510 1.01 x 109 2,5 2.000 2.30 x 109 3.0 3.400 3.10 x 109 4.300 4.0 3.50 x 10 4.400 Plot the data using Excel and label all axes and clarify all scales used. Submit the graph via email to your instructor. Indicate all growth phases observed for the Salmonella culture. Please ensure that you include your name in the Excel document as unnamed files will not be graded. You could use only one Excel file to send the two plots required for this assignment. Please also ensure that you include the data in the Excel document for reference. The latter indicates that you will have to place the date in the Excel file cells so that you could generate the graph. The two graphs must be generated on the same plot, that is, this will be a 3 axes graph. Please consult your supporting power point presentation to construct this particular graph with the indicated data. Remember that l will not consider this extra credit assignment for grading if you do not provide me the Excel file with the indicated growth curves and l will assign a "0" grade for the whole extra credit assignment. Part A The adaptation phase for the S. typhimurium culture lasted using the viable plate count data. 3 hours 0.5 hour 1 hour 2 hours 1.5 hours Submit My Answers Give Up

Explanation / Answer

A)

According to viable count data, the adaptation of S. typhimurium to culture medium is lasted for 1 hour. This is because, initially the cell count decreased but constantly increased from 1 hour onwards. Option 3 is correct.

B)

According to the O.D obtained, the adaptation of S. typhimurium to culture medium is lasted for 1 hour. Option 1 is correct. This is because, the O.D increased is corresponds to increased number of viable counts.

C)

According to bacteria growth curve, the phase in which the bacterium is adapted and adjusted to culturing environment is called as lag phase. Option 3 is correct.

D)

According to viable count data, the exponential phase of S. typhimurium is lasted for 3 hours. This is evident by increasing viable counts upto 3 hours. Option 5 is correct.

E)

According to O.D data, the exponential phase of S. typhimurium is lasted for 3 hours. This can be evident by increased O.D in response to increased viable cell count and thereafter maintained constant readings or slight change in the O.D. Option 1 is correct.

F)

The rapid growth phase is known as exponential phase or log phase in which, the number of bacteria is doubled. Option 4 is correct.

G)

The stationary phase is not clearly detected from the above given data. But, it can be assumed that the bacteria enter stationary phase between 3.5 to 4.5 hours according to O.D data which is maintained constant readings or slight change in the O.D can be detected. Option 2 is correct.

Related Questions

Navigate

• Browse (All)
• Browse I
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.