Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Microbes compete with animals for food by making it stink

03.11.2006
Microbes may compete with large animal scavengers by producing repugnant chemicals that deter higher species from consuming valuable food resources -- such as decaying meat, seeds and fruit, a new study suggests.

Ecologists have long recognized microbes as decomposers and pathogens in ecological communities. But their role as classic consumers who produce chemicals to compete with larger animals could be an important and common interaction within many ecosystems -- and one that scientists often overlook, according to the authors of a paper published this week in the journal Ecology.

"There is the notion that these spoiled resources are not that important," said Mark Hay, a Georgia Institute of Technology professor of biology, who led a team of graduate students conducting the research. "But when you total them up, they are appreciable, especially in marine ecosystems.

"Microbes that can hold onto these resources and use them for their own growth would be advantaged over microbes that could not prevent their resource from being consumed by animals," Hay added. "If microbes could produce chemicals that prevented crabs or fishes from using these resources, then those microbes should gain an advantage and become more abundant."

As part of an interdisciplinary graduate training program funded by the National Science Foundation, Hay, two of his faculty colleagues and four Ph.D. students tested this notion with a field and lab study they began at the Skidaway Institute of Oceanography near Savannah, Ga., in summer 2002. They were prompted by an assertion made in a paper published in 1977 by ecologist Dan Janzen, who suggested that microbes are rotting fruits, molding seeds and spoiling meat to make these resources repugnant to other animals, allowing microbes to consume them instead.

To test whether aged meat attracts fewer consumers than fresher meat, researchers baited crab traps with menhaden -- a fish typically used for bait -- that had been rotting in a pool of warm water – some of it for one day and the rest for two days. They also baited other traps with freshly thawed menhaden, which contained relatively few microbes. Then they set the traps in the marshes near Skidaway Island and caught hundreds of stone crabs, as well as other crab species, fishes and snails.

Many more animals were attracted to the freshly thawed bait than the rotten fish. "So we assumed that had to do with palatability," Hay said. "It could have been that the predators didn't smell the rotten fish, but that's not consistent with what we know about carrion on the roadway. It could have been that the predators smelled it, but didn't want it."

Counting the species found in the traps confirmed the level of attraction to the various forms of the bait, but it didn't necessarily test feeding, Hay noted. "It could be that the rotten food is just as good, but a lot of the good smells have leached out in the water, so maybe it's just food that's harder for predators to find," he explained.

Researchers assessed their questions about feeding by conducting laboratory experiments.

To eliminate food avoidance because of texture, they fed stone crabs, lesser blue crabs and striped hermit crabs noodle-like test foods made from pureed forms of either the freshly thawed menhaden or the rotten bait. Researchers found that, no matter the rotten bait's texture, stone crabs avoided eating the rotted, microbe-laden food, but readily consumed the freshly thawed menhaden containing few microbes.

"Even when the stone crabs were handed the rotten fish, they didn't want to eat it," Hay said.

Next, researchers tested whether microbes directly affected the palatability of microbe-laden, rotting food. They placed menhaden in two different pools for two days -- one group in seawater where microbes were allowed to grow naturally and the other in seawater with the antibiotic chloramphenicol added to suppress microbe growth. In the lab, stone crabs readily ate both freshly thawed menhaden and fish that had soaked in water with antibiotics, but refused to eat the rotten fish not protected from microbial attack.

To determine if reducing bacterial growth affected an animal's ability to find the bait, researchers also repeated the trapping experiment in the marsh, but used newly thawed fish, fish soaked in antibiotic treated water and fish aged without antibiotics. They found that both freshly thawed bait and aged, antibiotic-treated bait attracted animals more frequently than traps containing aged, microbe-laden menhaden.

Then researchers extracted various compounds from the microbe-laden bait to test whether chemicals produced by the microbes were indeed responsible for these feeding and attraction behaviors.

They found that chemical extracts composed of numerous compounds suppressed stone crab feeding when added to otherwise palatable fish flesh. But, of the several specific compounds they isolated and identified, none of the compounds by itself had this effect, Hay noted. So the researchers could not pinpoint a single compound causing the behaviors.

"But we can say the effect is chemical because we got rid of the nutrient and texture aspects of the bait and determined that it's something in this fraction of the bait's chemistry," Hay said. "It's either a complex mix of chemicals or perhaps something we destroyed during our lab test processes or maybe a chemical present in a very small amount that we failed to identify. There's uncertainty about this."

What's certain is that microbes are an omnipresent part of the ecosystem, Hay said. "They are not passively waiting on the bottom of the marsh floor for the rest of the community to deliver feces and other wastes that are not useful to anybody else," he added. "They are also trying to grab what they can at the start."

Hay hopes the research will make ecologists think more critically about the broad role of microbes in the ecosystem. Microbes are often omitted or relegated to a minor role in food web diagrams, but they should be depicted as direct competitors with larger animals, he said.

Jane Sanders | EurekAlert!
Further information:
http://www.gatech.edu

More articles from Ecology, The Environment and Conservation:

nachricht Upcycling 'fast fashion' to reduce waste and pollution
03.04.2017 | American Chemical Society

nachricht Litter is present throughout the world’s oceans: 1,220 species affected
27.03.2017 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

Bare bones: Making bones transparent

27.04.2017 | Life Sciences

Study offers new theoretical approach to describing non-equilibrium phase transitions

27.04.2017 | Physics and Astronomy

From volcano's slope, NASA instrument looks sky high and to the future

27.04.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>