[marcy29]

I am a micro student and have a question for anyone that can help. Here it is: Plating 1.0 ml of a sample diluted by a factor of 10(-3) produced 43 colonies. What was the original concentration in the sample? What about 0.1 ml of a sample? If anyone can help me with this i appreciate it! Thank you!
Marcy29

 

[ianiwane]

43000/ml ?? is that what you are asking?

 

[Kelley]

The original concentration is 43,000 c.f.u./ml.

(You diluted your culture by a factor of 1 to 1000. Hence, you multiply the number of colonies from 1 ml of diluted times 1000)

(c.f.u. = colony forming units)