A bacterial culture is diluted by 106. When O.1 ml of the diluted culture was sp

Question

A bacterial culture is diluted by 106. When O.1 ml of the diluted culture was spread on an agar plate containing a suitable growth medium, 85 colonies grew on the plate. What is the concentration of the bacterial cells in the original culture? Assume that the EOP -1 (i.e., each bacterial cell that was plated produced a single colony) Responses Reply Showing All Responses ordered by Newest Responses Assigned as Homework Question 6 70% ethanol in water is used both for disinfection and for washing precipitated DNA. What volume of 95% ethanol stock would you need to prepare 250 ml of 70% ethanol?

Explanation / Answer

According to the Chegg guidelines I'll answer the first question when more than one question is posted. Post them separately to get the answers.

Q-5

The concentration of bacteria in original sample is calculated by this formula

p = N/Vs * D

Where p = number of bacteria in the original sample.

N = Number of colonies on plate

Vs = Volume pipetted onto petri plate.

D = Dilution factor.

So, p = 85/ 0.1 * 10-6

p = 850 x 10 6

p = 8.5 x 108 cells/ml.

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