pH optimum for bacterial growth

Lesley Robertson L.A.Robertson at
Tue Aug 15 03:00:24 EST 1995

kafkwtz at ANDROMEDA.RUTGERS.EDU (David Kafkewitz) wrote:
>Good  buffers are a good choice only if the bacteria do not degrade them.
>They are a bad choice, in my opinion, for enrichment cultures, since you may
>enrich for buffer degraders.  Sodium bicarbonate and sodium carbonate, are a
>better choice.  The carbon dioxide buffer system is more ecologically
>correct than most other buffers.
>David Kafkewitz, Department of Biological Sciences,
> Rutgers University, Newark N.J. 07102, U.S.A.
> 201 648 5865; fax: 201 648 1007
>kafkwtz at

It really depends on the pH you want to achieve. We handle bacteria with 
pH optima at 2 and others at 10.5 - VERY different buffers required. I'm 
afraid you have to consider what you're trying to do, and design the 
system accordingly. Inorganic buffers have, indeed, the advantage that 
they're not used as substrates by bacteria in enrichment colutures, 
ammonium oxidizing nitrifiers will be inhibited by high phosphate 
concentrations, etc, etc. 
I've come in on the end of this discussion, and don't know what the 
original question was. If it's enrichments - we routinely use pH-stats, 
with autotitration, usually in the form of a continuous culture to avoid 
overloads of substrates (and thus huge pH fluctuations).

Lesley Robertson
L.A.Robertson at
Kluyver Laboratory, Delft University of Technology. 

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