Life on Earth as humans know it would not be possible without the variety and vast numbers of microorganisms that are frequently overlooked by most people. Some of these microbes are responsible for converting nitrogen, sulfur, and carbon- containing compounds into forms that benefit other organisms. A few are used in making foods and beverages. Others cause diseases. Visible evidence of these microbes abounds, from the holes left in Swiss cheese by Propionibacterium shermanii to the toxic black mold Stachybotrys chartarum, which threatens the health of residents of flood-damaged homes, to younger-looking faces thanks to a dilute solution of the toxin produced by Clostridium botulinum, to the fresh snow on the ski slope made by machines utilizing the corpses of Pseudomonas syringae.

Ingraham takes the reader on a series of "microbe sightings," using detailed examples to give the reader an appreciation for how humans' lives and environment are affected and shaped by bacteria, archaea, protozoa, fungi, and viruses. Within each themed chapter, he tells the story and history of several specific microbes, including a brief aside whenever the organism in question has a notable relative. For example, chapter 4, "Living Together," includes a section called "A Belching Cow." Here the reader learns the term eructate; that "a twenty-two gallon cow's rumen would be home to about a quadrillion microbes, about 200,000 times as many microbes as there are humans on Earth"; that the microorganisms produced in the rumen are "the ruminant's major source of protein"; that all five major types of microbes are present in the rumen; that dry dog food is treated so it has an odor similar to that of a rumen, but diluted in strength; and that certain Eskimo tribes that eat reindeer get sufficient vitamins by eating not just the meat, but also the contents of the reindeer rumens. Before the section is complete, cecal digestion of cellulose in organisms such as rodents, cellulose digestion in termites, and the possible use of some cellulose-digesting microbes in the production of biofuels are also discussed. This chapter has additional sections entitled "Spanish Moss," "A Fat Man and a Thin One," "A Gall on a Grapevine," "Small Points of Light on a Dead Fish," and "An Aphid Feasting on a Tender Rose Leaf." It also includes literary references from Jules Verne and Mark Twain; illustrations of how Agrobacterium tumefaciens transfers genes into a plant, and of an aphid eating while also giving birth; and stories of scientists from Carolus Linnaeus to Elie Metchnikoff to Jeff Gordon.

With a plethora of fascinating examples and engaging, engrossing writing, March of the Microbes is an excellent survey of microbial life that could even act as the text to accompany a high school elective on microbiology. Several AP Biology Readers who were coaxed into reading part or all of chapter 5, "Cycling Nitrogen," and learned of the anammox process were convinced of the merits of this book. (This process, discovered in the 1990s, may "account for as much as two-thirds of the flow of fixed nitrogen back to the atmosphere" in marine sediments and other environments.) The detailed lives of many organisms with various levels of impact on us and our world are presented with just enough detail to satisfy, even fascinate, but not overwhelm the reader.

Unfortunately, there are a few notable errors in the text, such as an indication that sperm do not contain mitochondria and one reversed arrow in a food chain diagram, thus showing methanogenic archaea using rather than producing methane. Hopefully such errors will be corrected before a paperback version of the book is issued. While there is a helpful glossary in which one can be reminded of what PM means (precursor metabolite), there is no bibliography. Thus, the reader must resort to an online search engine to find further information about a particular microbe. Nevertheless, when nearly every page presents nuggets to share with students and colleagues, and when the reader does not want to stop in the middle of a chapter, March of the Microbes must receive a high recommendation.