A
urine sample is diluted 1:100. 200 µl of the 1:100 dilution is
spread onto an agar plate. After incubation, 250 colonies are
observed. What is the concentration of bacteria in the original
urine sample? Show your work and include proper units for full
credit.
CFU/mL= number of colonies/( volume plated in mL dilution)
dilution= 1/100
number of colonies= 250
volume plated= 200 uL
1mL= 1000 uL
200 uL= 200/1000=0.2 mL
volume plated in mL= 0.2 mL
CFU/mL= 250/(0.2(1/100))
= 125000 /mL
concentration of bacteria in the original urine sample = 125000 cells/mL
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