Bacteria

bacteria minute single-celled organisms which are present more or less everywhere. They resemble plants more than animals, but are usually considered as belonging to a third kingdom, Protista, in which they constitute the group Schizomycophyta. With a few exceptions, they do not feed by the ordinary plant process of photosynthesis but live, according to type, on an enormous range of substances including practically everything found in food, as well as in live animals or plants. They reproduce by splitting in half and some, in ideal conditions, can do this every twenty minutes, so they can spread very fast.