12. You are doing a viable cell count on a bacterial culture and you perform ten

Question

12. You are doing a viable cell count on a bacterial culture and you perform ten-fold serial dilutions as shown in Figure 4.14 of your text. You count 130 colonies on a plate that was spread with 0.05 ml of a 10-6 dilution of the original culture. How many viable cells per milliliter are there in the undiluted bacterial culture? Show your work. 13. At the same time that you did the viable cell count of your bacterial culture (in problem 12), you also counted the cells in a Petroff-Hausser chamber; however, the cell count you obtained from Petroff-Hausser chamber is nearly double that obtained in the viable cell count. Based on this result, what might you conclude about the growth phase of the bacterial culture you are working with - was it likely to be in lag phase, exponential or stationary phase. Explain your answer.

Explanation / Answer

Final cell count = 130 colonies from 0.05 mL of final dilution
= 130 X 20 = 2600 colonies/mL

Dilution = 1/106
Original cell count = 2600 X 106 = 2.6 X 109 cells

The cells are in exponential phase.
Hence the cell count has become double in Petroff-Hausser chamber.

Related Questions

Navigate

• Browse (All)
• Browse 1
• Subjects

---

---

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