Sugarhead whiskey with spent grain

[dans.brew]

Dan it adds flavour also but the technique was used to lower ph to keep unwanted bacteria out.. :-B

Apart from doing sour mash's i really thought it was all about flavour profile building, anyway there you go... learnt something new.
So is bacteria not active below a certain ph level or different bacteria active at different ph readings?
Thanks bluc :handgestures-thumbupleft: