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Microbworld: Discover Unseen Life on Earth
Visit this terrific site "to find out all about the world of microbes from your own hands to the mighty Himalayas, landfills to oil spills, common colds to uncommon cures, under microscopes and in the news."
University of California
Ucmp: Introduction to Bacteria
This site provides an introduction to bacteria and examines fossil records, life history and ecology, systematics, and morphology.