Calculation of Total % Adhered Bacteria

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pankajjbarua
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Joined: Wed Sep 23, 2020 7:05 pm

Calculation of Total % Adhered Bacteria

#1 Post by pankajjbarua » Wed Sep 23, 2020 7:07 pm

Hello friends:
I need to calculate the Total % Adhered Bacteria for E.coli

I counted the CFUs and they were
566 at 10-2 dilution and 68 at 10-3 dilution

Now to calculate the Total % Adhered Bacteria I am using the following formula

Number of colonies adhered X dilution factor X 100/ Original inoculum

Also to calculate the original inoculum I am using the following formula:
(OD600 x 7.65) – 0.3 =? X 10^9 CFU/mL
For E.coli the ED600 value I got was 0.183
and after calculation the value I got was 1.09 X 10^9 CFU/mL

Now coming back to the calculation of Total % Adhered Bacteria
For 10-2 dilution I am doing this:

566 X 0.01 X 100/1.09 X 10^9 CFU/mL

Where 566 is the CFU count I counted after incubation
0.01 is the dilution factor and 1.09 X 10^9 is the original inoculum.

Please let me know if I am doing it right.

thanks

Plasmid
Posts: 566
Joined: Mon Sep 28, 2020 5:34 am
Location: North GA
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Re: Calculation of Total % Adhered Bacteria

#2 Post by Plasmid » Fri Nov 13, 2020 3:22 am

Hello, so are you trying to figure out the original bacterial count on a sample trough a dilution solution? Did you get a an individual colony count 30-300 on a streak plate?
Example

10ml pipetted 0.1 into a sterile of 9.9ml and so on?
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