Marine bacteria's mealtime dash is a swimming success

Prof. Roman Stocker of MIT holds three microfluidics devices, which provide realistic habitats for studying marine bacteria and their mealtime behavior in the laboratory. Click here for more information.

CAMBRIDGE, Mass. — Goldfish in an aquarium are able to dash after food flakes at mealtime, reaching them before they sink or are eaten by other fish. Researchers at MIT recently proved that marine bacteria, the smallest creatures in the ocean, behave in a similar fashion at mealtime, using their swimming skills to reach tiny food patches that appear randomly in the ocean blue.

The behavior of bacteria at these small scales could have global implications, possibly even impacting the oceans’ health during climate change.

Scientists in the Department of Civil and Environmental Engineering demonstrated for the first time in lab experiments that the 2-micron-long, rod-shaped marine bacterium P. haloplanktis is able to locate and exploit nutrient patches extremely rapidly, thanks to its keen swimming abilities.

Food sources for these microorganisms come as dissolved nutrients and often appear as localized patches that, if not eaten, are rapidly dissipated by physical processes like diffusion. Foraging, then, becomes a race against time for a bacterium. A rapid response gives it a strong advantage over competitors and may allow it to take up nutrients before they undergo chemical changes. A paper scheduled to publish in the Proceedings of the National Academy of Sciences online Early Edition the week of March 10 describes the research.

“Our experiments have shown that marine bacteria are able to home in very rapidly on short-lived nutrient patches in the ocean,” said Roman Stocker, the Doherty Assistant Professor of Ocean Utilization and lead author on the paper. “This suggests that P. haloplanktis’ performance is finely tuned to the oceanic nutrient landscape. If you are a bacterium, the ocean looks like a desert to you, where food mostly comes in small patches that are rare and ephemeral. When you encounter one, you want to use it rapidly.”