Please show work! Thanks 8. You are performing a viable cell count of bacteria.
ID: 216438 • Letter: P
Question
Please show work! Thanks
8. You are performing a viable cell count of bacteria. The original broth has an unknown concentration of bacteria. You dilute the culture as shown in the diagram below and plate 0.1 mL of the last three dilutions onto three petri dishes with nutrient agar. The following day you count the number of colonies on the plates with the results shown in the illustration below. What was the concentration (cells per mL) of bacteria in the original tube (using the most accurate plate for the calculation)? Show your work. Box your final answer. 1mL+ 9 mL 0.1 mL+9.9 ml mL9 mL 1 mL+9 mL Original broth 1/10 1/10 1/100 1/10 0.1 mL 0.1 mL 0.1 mL 32 colonies 4 colonies 0 coloniesExplanation / Answer
ANSWER 8.
The plates with 4 and 0 colonies are way too less to be counted as being valid.
The plate with 32 colonies, has underwent a 1/10, 1/10, 1/100 and followed by 0.1 ml plating, so it comes out to be a 10*10*100*10 = 100000 dilution factor.
Now, 32 colonies must have been present in 1/100000 of an mL. So 1 mL will contain 3200000 Colony Forming Units / mL.