Apr
13
2011

Earth, our place in space
Earth, our place in spaceCourtesy NASA
Life scientists study…well, life. They want to know everything about living things on planet Earth. One of the first things biologists want to know is who’s here. What kinds of plants and animals live in a forest? --or in a field? –or in the ocean?

If you’re an oceanographer who studies marine mammals, perhaps you’d go to sea on a ship with a good pair of binoculars and hunt for whales. As you focused your binoculars you’d be able to see different kinds of whale species. As you looked closer, for example at Humpback Whales, you'd see that each individual whale has a different black-white pattern on its tail. You might even take a biopsy, a small sample of whale flesh, and do a more detailed study of genetic differences among individual Humpbacks.

But what if you’re a microbial oceanographer? You sure can't use binocs to hunt for microbes! How can you study individual differences among tiny creatures that are only one-one-hundredth the width of a human hair? How do you hunt and capture single-celled bacteria, like Prochlorococcus, the most common bacterial species in the world’s ocean?

Invent something!

laser-based micro-fluidic system
laser-based micro-fluidic systemCourtesy C-MORE
Young scientists, Sebastien Rodrigue and Rex Malmstrom, at the Center for Microbial Oceanography: Research and Education (C-MORE) were doing research in Dr. Sallie Chisholm’s C-MORE lab at the Massachusetts Institute of Technology when they adapted a “laser-based micro-fluidic system” used commonly by medical researchers, for the study of marine bacteria. With this method they could put each individual tiny Prochlorococcus cell into its own little pool of seawater.

And then the excitement began.

Prochlorococcus
ProchlorococcusCourtesy Dr. Anne Thompson, MIT
Even in scanning microscope photographs, each Prochlorococcus looks like just another teeny, tiny balloon; we can't see any individual differences. However, Sebastien and Rex used fast and inexpensive genetic methods and discovered an extraordinary variety of individual differences among Prochlorococcus. Of course the variety among these microbes doesn't have to do with tail patterns, like whales. Prochlorococcus vary in their method of getting nutrients, like iron, out of seawater.

So what? Why do we care?

We care A LOT because microbes like Prochlorococcus are operating at the nitty gritty level of cycling not only iron, but also other elements in the ocean. Like carbon. That's right, as in carbon dioxide accumulating in our atmosphere -- and ocean -- causing climate change and associated problems. The more we understand about individual differences among oceanic microbes, the more we'll understand how they influence and respond to changes in Earth's climate.

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