Plotting growth data

Peter Herman herman at populus.slu.se
Wed Sep 27 03:03:07 EST 1995

hantash (hantash at dopey.cc.utexas.edu) wrote:

: Also remeber When taking ABs. readings that go beyond say 0.8 to dilute 
: your culture
: before taking the reading. This is because alot of people don't do this and
: you end up seeing growth curves with a stationery phase (what ever
: that phase may be) at Abs 1 when infact the culture is still
: in the "exponential phase" !!
: This is incorrect. As the cultre density rises, the ability of the spec to 
: read light scattering is compromised. The machine can read through a 
: certain range only. 

Another important thing to keep in mind is the biology of the organism.  
Extinction due to light scatter is more sensitive to particle number than 
to particle size so that organisms which stick together in clumps as 
density increase start to give problems unrelated to the OD range per 
se.  A long time ago, I worked with Mycobacterium phlei which is quite 
hydrophobic and caused no end of problems in estimationg growth by OD


R. Peter Herman				email	Peter.Herman at mv.slu.se
Sveriges Lantbruksuniversitet		Phone:	+46 18 67 12 20
Inst. f. Markvetenskap			Fax:	+46 18 67 27 95
S750 07 Uppsala, Sweden		

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