Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Time to rewrite the species rulebook

09.02.2005


From person to piranha to petunia, it’s pretty easy to spot different species in the human-scale part of the plant and animal kingdoms. But a new study shows that species differences aren’t so clear, at least as currently measured, when it comes to microscopic bacteria.



MSU researchers have spotted significant differences in genetic libraries among thought-to-be similar bacteria strains. The results, published this week in the journal the Proceedings of the National Academy of Sciences, suggest that new definitions are needed to catalogue bacteria – single-celled organisms with at least a 3.5 billion-year history. "It’s important to point out the importance of these small microbes on Earth; even though they are small, their mass in soil and water is equal to that of all plants," said MSU microbiologist James Tiedje, one of the study’s authors. "Furthermore, they are responsible for recycling the key elements of life so life on Earth can continue."

DNA, used by all life including bacteria to store genetic information, is a double-stranded molecule. When a given DNA molecule is split in two, for instance by heating it up, its two strands will spontaneously find each other, or reassociate, when the temperature drops. Scientists have long exploited this fact in their rough rule-of-thumb approach for saying just what makes up a species of bacteria. Single strands of DNA from two bacteria are mixed together. If most of these strands reassociate – specifically, if 70 percent of strands from bacteria A come together with strands from bacteria B – then the two bacteria strains are said to members of the same species.


Tiedje and his MSU colleague, microbiologist Konstantinos Konstantinidis, set out to put this mix and match approach to the test. The two scientists selected 70 related bacteria whose genomes, or complete genetic libraries, had been fully sequenced. A sequenced genome gives scientists what amounts to a card catalogue guide to an organism’s genetic information.

The MSU scientists downloaded the already-sequenced bacteria genomes from a variety of sites on the Internet. Then they did some cross-card catalogue comparisons. To their surprise, many bacteria that are considered members of the same species by the current mix and match approach, often share as few as 65 percent of their genes. Humans, in comparison, share 75 percent of their genes with fish. No one’s calling for the species rules to be rewritten so that humans are lumped with their distant underwater relatives. And when it comes to bacteria, the authors say, the current species definition appears to be too liberal.

Much of the differences between genetically-similar bacteria appear to be the result of environmental pressures. E. coli bacteria, for instance, exists everywhere from the intestines of warm blooded animals to paper mills. Any new way of tallying up bacteria species should "accommodate the ecological distinctiveness of the organisms," the authors write. "The point is about the value of a correct understanding of species – people expect a species to have certain traits and live in certain habitats," said Tiedje, whose work is also supported by the Michigan Agricultural Experiment Station. "If the species definition is not reasonably predictive of this, then it loses its value. This can be important for pathogen identification, quarantine or biotechnology, for example."

Konstantinidis and Tiedje also noted that even bacteria with genetic card catalogues that were as much as 99 percent similar had enough outward differences to be separate species. This shouldn’t come as a shock. Humans and chimpanzees, in comparison, share 98.7 percent of their DNA. But that small difference at the genetic level results in a big difference when it comes to outward appearance and Konstantinidis and Tiedje’s work is supported by the Bouyoukos Fellowship Program, the U.S. Department of Energy’s Microbial Genome Program, the Ribosomal Database Project and the MSU Center for Microbial Ecology.

Jim Tiedje | EurekAlert!
Further information:
http://www.msu.edu

More articles from Life Sciences:

nachricht Closing the carbon loop
08.12.2016 | University of Pittsburgh

nachricht Newly discovered bacteria-binding protein in the intestine
08.12.2016 | University of Gothenburg

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Closing the carbon loop

08.12.2016 | Life Sciences

Applicability of dynamic facilitation theory to binary hard disk systems

08.12.2016 | Physics and Astronomy

Scientists track chemical and structural evolution of catalytic nanoparticles in 3-D

08.12.2016 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>