ENUMERATION OF BACTERIA: 2314 Manual - Ex 19, p. 55; 3054-Ex 21, p. 93 We will S
ID: 195780 • Letter: E
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ENUMERATION OF BACTERIA: 2314 Manual - Ex 19, p. 55; 3054-Ex 21, p. 93 We will Small Square First period Follow the dilution and plating procedures outlined in the lab manual. To calculate percent viability, it is necessary to obtain an estimate of the number of yeast cells per ml in the original yeast suspension. The procedure is called a direct count, and a special counting chamber is used. The drawing below shows the region of the counting grid to use for the count. Count the number of yeast cells in six small square. Count contiguous squares in rows to avoid bias in selecting squares squares and calculate the average number of cells per Conversion Factor: Each small square accurately represents a volume of 1/(4x10%) mls liquid in the counting chamber. Therefore, to calculate the number of cells per ml, use the following equation No. cells per ml suspension- Avg, no. cells per square x (4 x 10+C) where, 4 x 10% sonversion factor for this counting chamber. Second Period Couint the yeast colories on a plate that has betwesen 0and 300 clonies uintheubc rolony counter if necessary for single cell in the original suspension. Calculate the number of viable cells per ml in the original suspension and percent viability of the cell suspe nsion according to the following equations: No Colony Forming UnitsCF.Ux Dilution Factor (see below) No, viable yeast cells Dilution plated No, viable yeast cells per ml. x 100% Percent ViabilityNo.yeast cells per ml. count L (Direct
Explanation / Answer
B. lets first chek the dilution of each tube
tube A ( 1 ml solution in 9 ml) =1/ 1+9=1/10 or 1:10
tube B ( 1 ml solution in 9 ml )= 1/ 1+9=1/10 X 1/10= 1/100 or 1:100
tube C(1 ml fro tube A to 99ml solution )= 1/1+99=1/100 X1/100 = 1/ 10000 or 1:10000
tube D ( 1 ml fro tube B to 9 ml)= 1/1+9=1/10 X 1/10000=1/100000= 1:100000
Now in tube C ; The number of colonies = 350
No of colonies in original solution = plate count X dilution factor=350 X 10000==3,500,000=3.5 X 106/ ml
c
If we count dilution D,
plate count = 34
then total number of cells = plate count X dilution factor = 34 X 100000 =3,400,000= 3.4 X 106 /ml
D. the formula of viable cell count from palte D
percent of viable cell= no of viable cell per ml/ no of yeast cell from direct plate count ( per ml) X100
=3.4 X 106 / 4.4 X 106X 100
as the viable cell count from plate D is 3.4 X 106 and total cell count with the chamber is 4.4 X 106
=3.4 X 105 / 4.4 X 106 X 100
= 0.77 X 100
= 77%
=7.7 %
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