The microbrewery would like to produce a 50gallon trial batc

The microbrewery would like to produce a 50-gallon trial batch of Ale which requires a pitch on of wort. The yeast is first grown in a defined growth medium and the cells are by centrifugation. a. How many yeast cells are required to achieve the correct cell density in 50 gallons of Ale wort? b. Yeast can grow to about 2 times 10^8 cells/ml. To be able to harvest this many yeast cells, what volume of yeast culture do you need to grow to correctly pitch a wort the volume of 50 gallons? Show your work The arrow points to an isolated colony on this plate. What Is the minimum number of yeast cells that were needed to produce this colony? You have two cultures of the same strain of yeast in the same medium. You determine that the OD woof the two cultures is about the same, but when you determine the number of cells per ml for both cultures, the numbers differ significantly. The table below shows a summary of your data. Briefly explain the reason for this discrepancy.

Solution

Answer:

a) converting gallons to ml

1 gallon = 3785.42 ml

now to achieve this pitch rate is 12x 10⁶ cells per ml

therefore 1 ml = 12X 10⁶ cells

3785.42 ml = 12X 10⁶ X 3785.42

1 Gallon = 12X 10⁶ X 3785.42 cells

1 Gallon = 45425.04 X 10⁶ cells

50 Gallons = 45425.04 X 10⁶ X 50 cells

50 gallons = 2271252 X 10⁶ cells

= 22.7 x 10¹² cells

therefore 22.7 x 10¹² cells are needed for the correct cell density in 50 Gallons

b) according to question the cell density that the yeast can grow is 2 X 10⁸ cells/ml

therefore, 2 X 10⁸ cells = 1 mL

1 cell = 1 / (2 X 10⁸⁾ mL

Since the required cell density as calculated in option 1 = 22.7 x 10¹² cells

and 2.27 X 10¹²   cells = [ 1/  (2 X 10⁸)] X 2.27 X 10¹² mL

= 1.135 X 10⁴mL

c) to get minimum number of cells in a colony, the colony will have to be picked, serially diluted and counter under the microscope to get exact cell number.

d) The difference is there because the spectrophometer O.D is dependent it is the relationship between Biomass and O.D and not cells and O.D

Larger cells absorb and scatter more light than more smaller cells.

relationship between O.D and biomass is not linear but is approximated to be linear at lower O.Ds i.e. between 0.3 and 0.4.

Since the O.D is higher in this case, hence the abberation in the actual and the calculated cell number.