> OK, what is ML bacteria, and what fruits/juices/must do/don't you
> want them in?

ML bacteria are bacteria which conduct malolactic fermentation (MLF).
At the most basic level that means they eat up malic acid and produce
lactic acid. MLF is suitable for wines where a reduction in acidity is
desired (and/or stability re MLB is an issue) and the wine style is not
so much focused towards varietal aromas and flavours.

For more, see:
http://members.tripod.com/~BRotter/MLF.htm

Ben