In article <20OCT199618511972 at ubvms.cc.buffalo.edu>,
jxie at ubvms.cc.buffalo.edu says...
>>Hi, there,
>> I'm trying to maintain pH value at 7.0 or 5.5 to culture
>S.mutans GS-5. I used PBS. But it doesn't work. After o/n, the pH
>value drops down too much. Anybody out there knows which buffer
>I should use, please reply to this account. Thanks a lot in
>advance.
>>Jinling Xie
I agree with Robert Randolph; adding chunks of solid calcium carbonate is
a good method if you can't use a pH-controlled fermentor. We used to use
sticks of calcium carbonate broken into pieces. As acid is produced by
the bacteria, they dissolve and neutralize the acid, but do not dissolve
until the pH gets down around 5.5 or lower. It just looks kind of
strange to have these white "rocks" in the bottom of your vessel.
Greg Cote
USDA
