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Dilution and Colony-Forming Units

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Ten grams of hamburger were added to 90 mL of sterile buffer. This was mixed well in a blender. One-tenth of a mL of this slurry was added to 9.9 mL of sterile buffer. After thorough mixing, this suspension was further diluted by successive 1/100 and 1/10 dilutions. One-tenth of a mL of this final dilution was plated onto Plate Count Agar. After incubation, 52 colonies were present. How many colony-forming units were present in the TOTAL 10 gram sample of hamburger?

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Ten grams of hamburger were added to 90 mL of sterile buffer. After blending this with sterile buffer, you have concentration of X in the hamburger/sterile buffer. You are making dilutions to find a concentration, after which you will have colony forming units. Colony forming units are colonies of bacteria that form from the replication of a single bacteria. So if you can dilute your sample to a ...

Solution Summary

This solution helps find the number of colony-forming units given information about dilutions. A step by step explanation is given, in 285 words.

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please help me understand the following dilution schemes

Consider the following dilution scheme:

A. 1oomL lake water
B. 5mL lake water into 45 mL diluent 0.1 ml - colonies TNTC
C. 1mL from B into 9ml diluent 0.1 ml - colonies 425
D. 0.5mL from C into 4.5 mL diluent 0.1 ml - colonies 58
E. 2mL from D into 19mL diluent 0.1 ml - colonies 12
F. 0.1mL from E into 0.9 mL diluent 0.1 ml - colonies 1

a. What dilution is achieved by adding 2mL of incoulum to 19mL of a diluent?
b. Would you expect any change in the answer of the above problem if the firat dilution was made by adding 1 mL of sample to 9 mL of diluent? Why or why not?
c. What are the total number of CFU's in the entire 100mL amount of the original lake water sample?

HELP! I'm stumped on how to do this!!!!

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