Featured Research

from universities, journals, and other organizations

It's A Stirring Tale Of Bacteria

Date:
February 13, 2004
Source:
University Of Arizona
Summary:
Poetry in motion are not words usually applied to bacteria. But when researchers at the University of Arizona looked into a petri dish, that's what they saw. Groups of bacteria streamed through the fluid, creating an ever-changing pattern of swirls and blips visible to naked eye.

Over time, currents and vortices are created when large concentrations of bacteria swim through fluids. These images show how the vortices develop in a drop of fluid about one-half-inch in diameter.
Credit: Image courtesy of Raymond Goldstein.

Poetry in motion are not words usually applied to bacteria. But when researchers at the University of Arizona looked into a petri dish, that's what they saw.

Groups of bacteria streamed through the fluid, creating an ever-changing pattern of swirls and blips visible to naked eye. In a bacterial ballet, the tiny organisms seemed to be moving through the fluid of the dish in coordinated fashion, almost like flocking in birds or schooling in fish.

"We all looked at this and said, 'Oh my goodness, why is this happening?' We were all surprised. We are still surprised," said Raymond Goldstein, professor of physics and applied mathematics at the University of Arizona in Tucson. On Monday, Feb. 16, at 5:30 p.m., he will give a presentation at the Biophysical Society annual meeting in Baltimore about the phenomenon, which he and his colleagues call "self-concentration."

Other members of the UA research team are John Kessler, emeritus professor of physics, and UA graduate students Christopher Dombrowski, Luis Cisneros, and Sunita Chatkaew. Some of the research funding was provided by the National Science Foundation.

Although there had been theoretical suggestions that such "flocking" behavior might be not be limited to birds or fish, this could be the first time it's been observed in bacteria.

The bacteria the UA team observed, Bacillus subtilis, swim by rotating a series of corkscrew-like appendages, called flagella, that are about five times the body length of one of the rod-shaped bacteria.

In a culture, when a bacterium uses up the dissolved oxygen nearby, it swims toward the oxygen-rich surface. So do all its fellows. But at the same time gravity acts to pull the bacteria back down. The swimming-up and sinking-down sets up a convective current, much as does cold air sinking toward the floor of a room.

The currents created by one swimming bacterium affect the others. Once a critical concentration of bacteria is reached, the motions of thousands of flagella set up additional large currents in the fluid, creating the organized jets and vortices observed by the UA team.

"This is like a large group of people who, by the very act of swimming in a pool, get carried around by the mutually reinforcing turbulence their swimming created," said Goldstein.

Bacteria sometimes act in concert once a certain number of them are massed in one place. They may detect each other's presence by chemicals each secretes into the medium, a phenomenon called 'quorum sensing.' Bioluminescent bacteria, for example, use quorum sensing to know when to turn on their lights. Quorum sensing is also used by the bacteria that cause gum disease.

Goldstein said the swirls and jets the researchers observed effectively stir the fluid, making it well-mixed. That could help the bacteria detect one another.

The team's next step is developing mathematical models that can predict and describe the phenomena. Ultimately, he said, the work may have applications in biotechnology under circumstances where researchers need to have minute quantities of solutions well-mixed.


Story Source:

The above story is based on materials provided by University Of Arizona. Note: Materials may be edited for content and length.


Cite This Page:

University Of Arizona. "It's A Stirring Tale Of Bacteria." ScienceDaily. ScienceDaily, 13 February 2004. <www.sciencedaily.com/releases/2004/02/040212090156.htm>.
University Of Arizona. (2004, February 13). It's A Stirring Tale Of Bacteria. ScienceDaily. Retrieved July 25, 2014 from www.sciencedaily.com/releases/2004/02/040212090156.htm
University Of Arizona. "It's A Stirring Tale Of Bacteria." ScienceDaily. www.sciencedaily.com/releases/2004/02/040212090156.htm (accessed July 25, 2014).

Share This




More Plants & Animals News

Friday, July 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

How to Make Single Serving Smoothies: Howdini Hacks

How to Make Single Serving Smoothies: Howdini Hacks

Howdini (July 24, 2014) Smoothies are a great way to get in lots of healthy ingredients, plus they taste great! Howdini has a trick for making the perfect single-size smoothie that will save you time on cleanup too! All you need is a blender and a mason jar. Video provided by Howdini
Powered by NewsLook.com
Boy Attacked by Shark in Florida

Boy Attacked by Shark in Florida

Reuters - US Online Video (July 24, 2014) An 8-year-old boy is bitten in the leg by a shark while vacationing at a Florida beach. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Goma Cheese Brings Whiff of New Hope to DRC

Goma Cheese Brings Whiff of New Hope to DRC

Reuters - Business Video Online (July 24, 2014) The eastern region of the Democratic Republic of Congo, mainly known for conflict and instability, is an unlikely place for the production of fine cheese. But a farm in the village of Masisi, in North Kivu is slowly transforming perceptions of the area. Known simply as Goma cheese, the Congolese version of Dutch gouda has gained popularity through out the region. Ciara Sutton reports. Video provided by Reuters
Powered by NewsLook.com
Tyrannosaur Pack-Hunting Theory Aided By New Footprints

Tyrannosaur Pack-Hunting Theory Aided By New Footprints

Newsy (July 24, 2014) A new study claims a set of prehistoric T-Rex footprints supports the theory that the giant predators hunted in packs instead of alone. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

    Health News

      Environment News

        Technology News



          Save/Print:
          Share:

          Free Subscriptions


          Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

          Get Social & Mobile


          Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

          Have Feedback?


          Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
          Mobile: iPhone Android Web
          Follow: Facebook Twitter Google+
          Subscribe: RSS Feeds Email Newsletters
          Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins