Q: how to maintain pH value to culture Streptoccus mutans GS-5?

cotegl at ncaur1.ncaur.gov cotegl at ncaur1.ncaur.gov
Wed Oct 30 10:31:53 EST 1996

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 
>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

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