CAMBRIDGE, MA -- For the kinds of animals that are most familiar to us ones that are big enough to see it's a no-brainer: Is it better to sit around and wait for food to come to you, or to move around and find it? Larger animals that opt to sit around aren't likely to last long.
But for bacteria out in the ocean, the question is a far more complicated one.
Oceanographers have long assumed that because turbulence distributes nutrients uniformly through the water, and because the ability of tiny organisms to move around is insignificant compared to this turbulence, there was no reason for such creatures to move at all. Sea-dwelling bacterial life, they believed, should consist just of static feeders.
That view has now been upended by research conducted by Roman Stocker, an associate professor in MIT's Department of Civil and Environmental Engineering, and John R. Taylor, a former MIT postdoc who is now a lecturer in applied mathematics and theoretical physics at Cambridge University. It turns out that swimmers and passive feeders each have some advantages but also pay some costs in food gathering, depending on how fast the swimmers swim and how strong the turbulence is.
The results, based on a computer model that for the first time considers nutrient competition by bacteria in a turbulent flow, have just been published in Science.
Until now, most studies of microorganism behavior have taken place in static environments, such as a test tube or Petri dish, without regard to fluid flow. "Marine bacteria have mostly been studied in isolation from the motion of the seawater they live in," Stocker says. These new computer simulations, which model both how water flows and how bacteria in that water behave, have now made it possible to study the foraging of bacteria in dynamic environments, similar to the turbulent waters they naturally inhabit.
"We're working at the interface between microbiology and fluid
|Contact: Sarah McDonnell|
Massachusetts Institute of Technology