O.D. 600 nm readings to bacterial concentrations

Mon Oct 16 08:41:27 EST 1995

Gerald Pier (gpier at warren.med.harvard.edu) wrote:
: In article <44rnn6$89o at news.internetmci.com>, "Gregory P. Harhay"
: <gpharhay at internetmci.com> wrote:

: > I need to convert my O.D. 600 nm "absorption" readings of pure
: > cultures of Pseudomonas fluorescens (ATCC 13525) and 
: > Brochothrix thermosphacta  (ATCC 11509) suspended in buffer
: > to an estimate of their concentration in the buffer. Are there
: > any good references out there? ATCC is no help
: > 
: > Thanks,
: > Greg Harhay

: One more thing to consider: Some organisms, like P. fluorescens, rapidly
: adhere to glass or plastic culture vessels in some buffers, particularly
: those lacking protein (i.e. saline, PBS, etc.).  So an OD reading followed
: by dilutions and plate counts can be highly misleading as the organisms
: stick to the dilution vessle walls quicker than you can pipette an aliquot
: into the next vessel.  So I'd be careful and do my dilutions for plate
: counts in several different buffers, including ones that have something
: like 1% proteose peptone or BSA in them.

: Jerry Pier


  Tina Coan                         Texas Institute for Applied
  Sr. Research Assistant            Environmental Research
  817/968-9563                      P.O. Box T-258
  fax 817-968-9568                  Tarleton State University
  email: coan at tiaer.tarleton.edu    Stephenville, Tx.  76402

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