You perform a spread plate to determine the bacterial population in a batch liquid media. You plate 0.1ml of a 10-5 dilution. You incubate the plate and count 10 colonies (cfu). What is the bacterial population in cfu/ml of the stock (undiluted) culture? 10 million colonies 1 million colonies 100 million colonies

Question

Biology

Sasha Weaver

16 June, 01:50

You perform a spread plate to determine the bacterial population in a batch liquid media. You plate 0.1ml of a 10-5 dilution. You incubate the plate and count 10 colonies (cfu). What is the bacterial population in cfu/ml of the stock (undiluted) culture? 10 million colonies 1 million colonies 100 million colonies

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Jonathan Ellison · Answer 1

Answer: 10 million colonies

The volume of media used is 0.1ml and the concentration diluted to 10^-5, so the actual volume used would be: 0.1ml * 10^-5 = 1ml * 10^-6

The media shows 10 colonies. The number of colonies per volume would be: 10 cfu / (1ml * 10^-6) = 10 * 10^6 cfu/ml = 10 million cfu/ml