Getting cultures to specific cfu - (Mar/19/2021 )

Hello I need to get a culture to specific cfu per ml. Do I make a culture and leave it overnight. Then use haemocytometer to see how many bacteria are in there and then work out how much I need to dilute it by. ?

Suggest you develop a standard curve - OD v. cfu.  Hematcytomer counts are a pain - esp. for bacteria

Thankyou for your suggestion. As far as I can see devices to measure OD is very expensive. I have been struggling with the haemocytometer for bacteria

Would you expect all the bacteria to be the same size in your sample on the cytometer. Seems like some are smaller than others.

Bacteria are hard to see and reliably count using a hemacytometer.  Look for a used Klett meter.

Thankyou I will. Is there a calculation you do when you have the turbidity measurement to see how many bacteria you have ?

No - take an OD AND a cfu count at various dilutions of a culture and plot OD v. log cfu.  Using that plot - you can roughly estimate count colony count based on OD.

Thankyou !