Suppose a scientist discovered a new type of humanoid: a being in many ways like a person that could also harness sunlight for energy and growth in ways similar to plants. The result’s easy to imagine. News outlets from the TV networks to supermarket tabloids would be trumpeting the story for days if not weeks.
Well, Edward DeLong has done something like that. And the main reason you didn’t see headlines about it at the checkout counter is that he doesn’t study human-scale organisms. Instead, his focus is entities — bacteria, mainly — far too small to be seen with the naked eye.
Bacteria don’t come in neat categories like “plant” and “animal.” Still, scientists had thought that in one respect — their ability to harness sunlight — a clear division existed, says DeLong, an MIT civil and environmental engineering professor. “The idea was that you have organisms that harbor chlorophyll, and they do photosynthesis,” he notes, “and then there’s everybody else, and they eat the photosynthesizers.”
But five years ago, DeLong, who also has an appointment in biological engineering, made the discovery that there are ocean bacteria which draw on both sunlight and microscopic prey for energy.
At the time, the fact that such “hybrids” existed was not itself news. The ability to combine a light-based energy-generating capability with one that involves consuming other microbes had been reported in some species of a class of micro-organisms called archaea. But these organisms were outliers. “They’re found only in very salty environments, like the Great Salt Lake,” notes DeLong. Now, it appears bacteria with those paired capabilities exist in untold numbers around the globe.
One reason this matters is that ocean bacteria themselves matter. Indeed, if there were no oceanic microbes, there might be no us, either. Water-borne bacteria, for example, are critical to keeping our climate stable: by metabolizing the carbon in carbon dioxide, they help prevent CO2 from building to dangerous levels in the atmosphere. In addition, such bacteria are almost unbelievably ubiquitous. “If you examined a random teaspoonful of sea-water at the beach,” adds DeLong, “there would be millions of microbes in it.”
The fact that many ocean microbes seem to function in unexpected ways has spurred excited speculation about exploiting them. Ideas range from new antibiotics to “bacterial fuel cells” that would end the world’s energy woes.
The potential for applications was one reason the Gordon and Betty Moore Foundation last year decided to provide generous backing for DeLong and his MIT colleagues, among others. DeLong himself believes there will be payoffs from his work, but cautions that at this point, we know precious little about microscopic ocean life.
“We estimate that over 99 percent of the microbes in the oceans have yet to be characterized,” he notes, “so the question is, How well do we understand the key processes going on out there?”