well from what i know from baking the only thing that will kill the yeast would be salt and water that is to hot, and as far as yeast goes you could honestly keep adding more sugar to the same container and it kep generating the gas. Like they do with sourdough or what they calla "pate fermente" sp? they have one pice of dough that was made anywhere from 1 to 120 years ago and they just contuine to "feed the yeast" i.e adding more sugar and water to the mix which keeps the fermentatipon process going. This is what gives sourdough its unique flavor, each time they make a batch of the bread they mix in a chunk of the old dough with the new dough.... thus making it "sourdough" so i would recomenond adding more sugar and stuff b/c eventully you bottle would become not so plesent smelling but the problen i run into with a larger container would be gerring the maximum amount of gas out of that mix b/c that much sugar and yeast would probally become pretty expensive and i would want to get as much as possible