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A Million Microbes

May 4, 2017

A million microbes may live in a single drop of seawater—producing, consuming, and excreting various chemical compounds. Scientists are closely examining this stew of compounds dissolved in the ocean to reveal previously unknown relationships among marine microbes. Some microbes, called autotrophs, make their own food, converting carbon dioxide via photosynthesis into organic carbon that other microbes, called heterotrophs, rely on for survival. At one extreme (left), all autotrophs may produce a variety of compounds that a variety of heterotrophs consume. At the other extreme (right), specific autotrophs may produce specific compounds that specific heterotrophs consume. And there are potential scenarios in between. (Illustration by Amy Caracappa-Qubeck, Woods Hole Oceanographic Institution)