The Hidden Power of Microbes

Continue your tour of Lina's microbiome by surveying the five major types of microbes: bacteria, archaea, fungi, protists, and viruses. Examine what they do and where they live in the human body. The statistics are astonishing, since just over half the cells in your body are microbes, comprising some 39 trillion microbial cells versus 30 trillion human cells. Plus, we harbor 380 trillion viruses!

Any part of the human body that has contact with the outside world is a potential homestead site for microbes. But why do our bodies tolerate their presence? Here, you'll answer the question: What are these microbes doing for you? One of their important jobs is to disarm potentially harmful microorganisms. Discover how they also aid in digesting complex molecules such as gluten.

Follow the steps that transform cacao beans into chocolate as an example of fermentation-an intricate process mediated by different microbes. The ability of certain microorganisms to turn nutrients into energy in the absence of oxygen is what makes fermentation possible. Also, look at wine, cheese, and yogurt production, and consider the health benefits of fermented foods as well as the risks.

Explore the diverse environments of the human gut from a microbe's point of view: the deadly acidic cauldron of the stomach, the constant antimicrobial rain in the small intestine, and the paradise of nutrients in the colon. Learn how good health depends on microbial fermentations churning away in our bellies. Every gut has its own unique mix of microbe species, but their functions are the same.

Microbes are known to make creatures do strange things, such as zombie ants that climb to a specific height to die and spread the infecting agent. Rabies is another example since it alters animal behavior to promote spread of the virus. Dr. Booth investigates whether microbes within us may hijack our minds for their own benefit. Discover that one line of defense is the blood-brain barrier.

Return to our fictional microbe host, Lina, who is now a toddler living in a rural setting. Compare her microbiome with that of her urban cousin, noting differences depending on pets, farm animals, siblings, playmates, and other factors. Evaluate the connection between allergies and exposure to different microbes. Also, consider the best diet to promote a healthy assortment of microorganisms.

Dig deeper into how microbes and hosts establish their symbiotic relationships, and how the human partnership with microbes can sometimes lead to chronic diseases. Find that some insects and animals have no microbiome at all. What they have instead is a readily digestible diet, with little or no assistance required from microorganisms. Dr. Booth also cautions against microbiome miracle cures.

The amazing adaptability of some microbes can create problems for us. A child's earache is a good example, resulting from the changed environment in the narrow inner ear canal during a cold, transforming harmless or even beneficial microbes into troublemakers. Turn back the clock to the origin of life on Earth to see how microbes have evolved to flourish under the most punishing circumstances.

Cover the incessant war among microbes, which can lead to collateral damage in humans. Look at cases of competitive exclusion, and tactics such as frontal assault, chemotaxis, chemical weapons, and coordinated and even suicidal attacks-all in the struggle to stay on top. The array of strategies underscores the intricate relationship between the ecology of microbes and human health.