microbes/bacteria have long been used to manufacture other things, that doesn't necessarily mean that it's a bad thing to come from yeast. For instance, many B vits are cultured from yeast.
And EVERY chemical compound has to be digested by the liver, EVERYthing, so you can't automatically say it's a bad thing. So long as the amounts are small the benefits of the aloe outweigh the negatives of the additives. Obviously if you can find a fresher source w/o preservatives that would be better, but to avoid something good just because something is slightly questionable gets you nowhere in the long term. :(