pH optimum for bacterial growth

[Andreas Brune]

In article <40qg7c$ger at synapse.bms.com>,
   mamber at synapse.bms.com (Stephen Mamber) wrote:

>You may be right, but I have had certain situations in performing 
>biological assays where sodium and potassium buffers were relatively
>useless.  In these situations, I have switched to Good buffers, such as 
>Tris and MES, with a noticeable improvement in buffering capacity/
>resistance to adverse pH changes during growth.

Sodium and potassium (ions) are not the buffering species in any case.
And you can hardly avoid them if you make up a MES buffer ;-)
And the buffering capacity is certainly not a parameter governed by the
type of buffer used but its concentration and pK value (relative to the
pH of the medium).

A problem of Good buffers is their price if you want to grow the microorganisms
in large volumes. But I certainly share the reservation against phosphate
buffers. Bicarbonate is indeed a good since natural buffering system. 
Unfortunately it calls for a defined (CO2-containing) headspace over the medium.

Regards,

Andreas Brune

Dr. Andreas Brune         	Phone: 	+49-7531-883282
Mikrobielle Oekologie     	Fax:   	+49-7531-882966
Universitaet Konstanz     	E-mail:	Andreas.Brune at uni-konstanz.de