RE: deer and corn?
It's not bacteria, it's the enzymes that change with the season to allow deer to digest foods with different fiber content. That is not the greatest threat to deer, however, when feeding corn. Many of the corn and corn products available through various distributors, are not certified as animal feeds and will flat out kill deer, turkeys or anything else that eats them.
If you have any questions or concerns about feeding deer or other wildlife, contact the wildlife biologist in your regional DNR office or your county agricultural extension agent. These folks are great sources of information and usually very happy to help out.