1 OD unit = bacterias per ml? - (Nov/07/2005 )

hi
Quite a basical question, but i'm not able to find the answer... When OD is 1, how much bacterias do you have in a standard culture?...
thanks in advance
fred

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hi
sorry.
Finally i founded the information.

1ml of a OD=1 culture of E. coli is 10^9 bacterias per ml.

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Where did you find the information as I am curious about how other OD readings correspond to cfus per ml?
Thanks.

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According to qiagen, 1x10^9 cells/ml = 1-1.5 at A[600].

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In fact it is compltetly depends on the strain of bacteria (even E. coli) you are working with. And even of the spectrophotometer as far as I have understood. If possible it is always best to make your own calibration.

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Canalon beat me to it -- it is (relatively) strain dependant -- the OD of a 10^9 cfu/ml culture of DH5alpha may or may not be the same as a culture of JM109, or HB101, or perhaps of some wild-type, full LPS E. coli strain...

It (cf/ml per OD) is quite considerably species specific...

I'd guess most lab strains of E. coli will behave pretty much the same, though, at least in the ball park, rather than logs difference. It depends on the accuracy you need...

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hi
well, i found the information on promega catalog and consider the information ok for E coli strains...

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As per my lab manual, there is 8x10 8 E. coli cells/mL at OD 600.

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