If you plated 0.1 ml from tube C and 1.0 ml from tube C and got the following re
ID: 273795 • Letter: I
Question
If you plated 0.1 ml from tube C and 1.0 ml from tube C and got the following results:Smal World Initiative Lab Manual D If you plated 0. 1 ml from tube C and 1.0 ml from tube C and got the following results: 0.1 ml plate 1 plate 296 plate 3 1.0 ml plate 1 plate 2455 plate 3 900 74 1020 How many bacteria were in the original culture? 3. You have performed the following serial dilution scheme: Dilution series A. 1 ml original sample+99 ml B. 1 ml A+99 ml C. 1 ml B+9 ml D. Imi C + 9 ml E 1 ml D +9 ml F. 1 ml E+9 m Results TNTC, TNTC, TNTC TNTC, TNTC, TNTC 389, 455, 509 42, 55, 89 9,7,6 1,0,0 If you plated 1 ml of each dilution, how many organisms are in 1 ml of the original sample? If you plated 0.1 ml of each dilution, how many organisms are in 1 ml of the original sample? 4. You have performed the following serial dilution scheme: A. 1 ml original sample + 99 ml B. ml A +99 ml C. 1 ml B+9 ml D. 1 ml C+9 ml E. 1ml D+9 ml TNTC, TNTC, TNTC TNTC, TNTC, TNTC 395, 465, 784 47, 55, 95 12, 9, 16 If you plated 0.1 ml, how many organisms are in 1 ml of the original sample? 5. If you were given a tube of E coli and 1-99 ml water blank, 2-9.9 ml water blanks 3.o ml water blanks, and 4 1 ml piptes, how would you reach a dilution of 107? (1:10,000,000) 12
Explanation / Answer
(3)
Serial dilution
Dilution factor in Tube A =10^-2
Dilution factor in Tube B =10^-4
Dilution factor in Tube C =10^-5
Dilution factor in Tube D =10^-6
Dilution factor in Tube E =10^-7
Tube D has countable number of colonies, therefore we could use it to calculate original CFU/mL
Original CFU/ml = ?
Dilution factor plate D= 10^-6
Number of colonies= (42+55+89)/3=62
Volume of sample =1 mL to the plate
cfu/ml = (no. of colonies)/( dilution factor x volume of culture plate)
cfu/ml = (62)/ (10^-6 x 1)
cfu/ml = 6.2 x 10^7 cfu/mL
When 1mL is plated the Original number of organisms per mL is 6.2 x 10^7
When 0.1mL is plated the Original number of organisms per mL is 6.2 x 10^8
(4)
Tube D has countable number of colonies, therefore we could use it to calculate original CFU/mL
Original CFU/ml = ?
Dilution factor plate D= 10^-6
Number of colonies= (47+55+95)/3=65.5
Volume of sample =1 mL to the plate
cfu/ml = (no. of colonies)/( dilution factor x volume of culture plate)
cfu/ml = (65.5)/ (10^-6 x 1)
cfu/ml = 65.5 x 10^6 cfu/mL
When 1mL is plated the Original number of organisms per mL is 65.5 x 10^6
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