Question

A) A 103 dilution is performed on a culture of bacteria in order to perform viable plate counts. From the dilution, 0.1 mL of solution is plated on solid media, and 177 colony forming units grow on the plate. How many bacteria are in a single mL of the original culture? Express your answer to two decimal places using scientific notation. In scientific notation 540 would be written as 5.4010^2. Since only 0.1 mL is put on the plate, this counts as an extra dilution!!! Any time less than 1 mL is transferred, a dilution is being performed. Any time more than 1 mL is transferred, a concentration is being performed. B) If you suspect your culture of bacteria has 7110^8 cells per mL, how many mL of original culture would you want to end up on the plate to produce 143 cfu? Express your answer in scientific notation rounded to two decimal places. Eg. 0.01001 would be 1.00*10^-2

          A) A 103 dilution is performed on a culture of
bacteria in order to perform viable plate counts. From the
dilution, *0.1
mL* of solution is plated on solid
media, and 177 colony forming units grow on the plate. 
How many bacteria are in a single mL of the original culture?
Express your answer to two decimal places using scientific
notation. In scientific notation 540 would be written
as 5.40*10^2. 
Since only 0.1 mL is put on the plate, this counts as an
extra dilution!!!
Any time less than 1 mL is transferred, a dilution is
being performed.
Any time more than 1 mL is transferred, a concentration is
being performed.
B)
If you suspect your culture of bacteria has 71*10^8 cells per
mL, how many mL of original culture would you want to end up on the
plate to produce 143 cfu?
Express your answer in scientific notation rounded to
two decimal places. Eg.  0.01001 would be
1.00*10^-2

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Added by Milagros C.

Biology for AP Courses

Julianne Zedalis, John Eggebrecht

Instant Answer

Solved by Expert Madhur L

04/10/2023

Step 1

We know that a 10^3 dilution was performed, and then 0.1 mL was plated. Since only 0.1 mL was plated, this counts as an extra dilution. So, the total dilution factor is 10^3 * 10 = 10^4. Show more…

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A) A 103 dilution is performed on a culture of bacteria in order to perform viable plate counts. From the dilution, *0.1 mL* of solution is plated on solid media, and 177 colony forming units grow on the plate. How many bacteria are in a single mL of the original culture? Express your answer to two decimal places using scientific notation. In scientific notation 540 would be written as 5.40*10^2. Since only 0.1 mL is put on the plate, this counts as an extra dilution!!! Any time less than 1 mL is transferred, a dilution is being performed. Any time more than 1 mL is transferred, a concentration is being performed. B) If you suspect your culture of bacteria has 71*10^8 cells per mL, how many mL of original culture would you want to end up on the plate to produce 143 cfu? Express your answer in scientific notation rounded to two decimal places. Eg. 0.01001 would be 1.00*10^-2

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Transcript

00:01 Hello student here the question is given and the question is about the dilution of a given bacterial sample.

00:07 So dilution or we can say the serial dilution question of the of bacteria sample will be given and here we have to find out the colony forming unit per ml.

00:19 So we know this can be calculated by the formula using this colony count which are plated in a particular plate.

00:28 So the bacteria present on that particular plate along with this plating factor the amount of volume which are plated and this is multiplied by the dilution factor.

00:45 So here the dilution factor is given which is 10 to the power 3 and these plating factor which are 1 is 0 .1 ml and this colony count is given so here this colony count is 177.

01:01 So we are have to in original sample so we have to this cfu amount in original sample we have to count.

01:10 So from there we putting the value simply 177 and this is 10 to the power 3 and this is 0 .1.

01:17 So by calculating this we can get this 177 into 10 to the power 3 into 10 to the power here it is also comes 10 because this is minus 1 so if we taking up then it could be this.

01:33 So if we write this 1 .77 into this 4 and this will be 2 so this could be 6 colony forming unit per ml in the original sample.

01:44 So this much of bacteria count colony forming unit in the original sample of given.

01:52 So this is the option for the a and similarly the second part of the question is given and second part of the question is if suppose the bacterial colony forming unit in original sample is given which is a 71 into 10 to the power 8 cells per ml.

02:15 So we have to know about the plating factor as well as we have to also calculate if the colony count is given and here the colony count is this 143...

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