Featured Research

from universities, journals, and other organizations

Hidden Diversity In Key Environmental Cleanup Microbes Found By Systems Biology Assessment

Date:
October 5, 2009
Source:
Georgia Institute of Technology Research News
Summary:
Researchers analyzed the gene sequences, proteins expressed and physiology of 10 strains of bioremediation microbes called Shewanella. Results showed surprising diversity not seen using traditional microbiology approaches.

Kostas Konstantinidis, an assistant professor in Georgia Tech’s School of Civil and Environmental Engineering, used genomics and proteomics to identify hidden diversity in the Shewanella family of bioremediation microbes.
Credit: Georgia Tech Photo by Gary Meek

Researchers have completed the first thorough, system-level assessment of the diversity of an environmentally important genus of microbes known as Shewanella. Microbes belonging to that genus frequently participate in bioremediation by confining and cleaning up contaminated areas in the environment.

Related Articles


The team of researchers from the Georgia Institute of Technology, Michigan State University and the Pacific Northwest National Laboratory analyzed the gene sequences, proteins expressed and physiology of 10 strains of Shewanella. They believe the study results will help researchers choose the best Shewanella strain for bioremediation projects based on each site's environmental conditions and contaminants.

The findings, which further advance the understanding of the enormous microbial biodiversity that exists on the planet, appear in the early online issue of the journal Proceedings of the National Academy of Sciences. This research was supported by the U.S. Department of Energy through the Shewanella Federation consortium and the Proteomics Application project.

Similar to a human breathing in oxygen and exhaling carbon dioxide, many Shewanella microbes have the ability to "inhale" certain metals and compounds and convert them to an altered state, which is typically much less toxic. This ability makes Shewanella very important for the environment and bioremediation, but selecting the best strain for a particular project has been a challenge.

"If you look at different strains of Shewanella under a microscope or you look at their ribosomal genes, which are routinely used to identify newly isolated strains of bacteria, they look identical. Thus, traditional microbiological approaches would suggest that the physiology and phenotype of these Shewanella bacteria are very similar, if not identical, but that is not true," explained Kostas Konstantinidis, an assistant professor in the Georgia Tech School of Civil and Environmental Engineering. Konstantinidis, who also holds a joint appointment in the School of Biology, led the research team in analyzing the data.

Using the traditional method for determining interrelatedness between microbial strains -- sequencing of the 16S ribosomal gene -- the researchers determined that the 10 strains belonged to the same genus. However, the technique was unable to distinguish between most of the strains or define general properties that would allow the researchers to differentiate one strain from another. To do that, they turned to genomic and whole-cell proteomic data.

By comparing the 10 Shewanella genomes, which were sequenced at the Department of Energy's Joint Genome Institute, the research team found that while some of the strains shared 98 percent of the same genes, other strains only shared 70 percent. Out of the almost 10,000 protein-coding genes in the 10 strains, nearly half -- 48 percent -- of the genes were strain-specific, and the differences in expressed proteins were consistently larger than their differences at the gene content level.

"These findings suggest that similarity in gene regulation and expression constitutes an important factor for determining phenotypic similarity or dissimilarity among the very closely related Shewanella genomes," noted Konstantinidis. "They also indicate that it might be time to start replacing the traditional microbiology approaches for identifying and classifying new species with genomics- or proteomics-based methods."

Upon further analysis, the researchers found that the genetic differences between strains frequently reflected environmental or ecological adaptation and specialization, which had also substantially altered the global metabolic and regulatory networks in some of the strains. The Shewanella organisms in the study appeared to gain most of their new functions by acquiring groups of genes as mobile genetic islands, selecting islands carrying ecologically important genes and losing ecologically unimportant genes.

The most rapidly changing individual functions in the Shewanellae were related to "breathing" metals and sensing mechanisms, which represent the first line of adaptive response to different environmental conditions. Shewanella bacteria live in environments that range from deep subsurface sandstone to marine sediment and from freshwater to saltwater. All but one of the strains was able to reduce several metals and metalloids. That one exception had undertaken a unique evolution resulting in an inability to exploit strictly anaerobic habitats.

"Let's say you have a strain of Shewanella that is unable to convert uranium dissolved in contaminated groundwater to a form incapable of dissolving in water," explained Konstantinidis. "If you put that strain in an environment that contains high concentrations of uranium, that microbe is likely to acquire the genes that accept uranium from a nearby strain, in turn preventing uranium from spreading as the groundwater flows."

This adaptability of bacteria is remarkable, but requires further study in the bioremediation arena, since it frequently underlies the emergence of new bacterial strains. Konstantinidis' team at Georgia Tech is currently investigating communities of these Shewanella strains in their natural environments to advance understanding of the influence of the environment on the evolution of the bacterial genome and identify the key genes in the genome that respond to specific environmental stimuli or conditions, such as the presence of heavy metals.

Ongoing studies should broaden the researchers' understanding of the relationship between genotype, phenotype, environment and evolution, he said.


Story Source:

The above story is based on materials provided by Georgia Institute of Technology Research News. Note: Materials may be edited for content and length.


Cite This Page:

Georgia Institute of Technology Research News. "Hidden Diversity In Key Environmental Cleanup Microbes Found By Systems Biology Assessment." ScienceDaily. ScienceDaily, 5 October 2009. <www.sciencedaily.com/releases/2009/08/090831213000.htm>.
Georgia Institute of Technology Research News. (2009, October 5). Hidden Diversity In Key Environmental Cleanup Microbes Found By Systems Biology Assessment. ScienceDaily. Retrieved October 25, 2014 from www.sciencedaily.com/releases/2009/08/090831213000.htm
Georgia Institute of Technology Research News. "Hidden Diversity In Key Environmental Cleanup Microbes Found By Systems Biology Assessment." ScienceDaily. www.sciencedaily.com/releases/2009/08/090831213000.htm (accessed October 25, 2014).

Share This



More Plants & Animals News

Saturday, October 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Deep Sea 'mushroom' Could Be Early Branch on Tree of Life

Deep Sea 'mushroom' Could Be Early Branch on Tree of Life

Reuters - Innovations Video Online (Oct. 24, 2014) Miniature deep sea animals discovered off the Australian coast almost three decades ago are puzzling scientists, who say the organisms have proved impossible to categorise. Academics at the Natural History of Denmark have appealed to the world scientific community for help, saying that further information on Dendrogramma enigmatica and Dendrogramma discoides could answer key evolutionary questions. Jim Drury has more. Video provided by Reuters
Powered by NewsLook.com
Black Bear Cub Goes Sunday Shopping

Black Bear Cub Goes Sunday Shopping

Reuters - Light News Video Online (Oct. 23, 2014) Price check on honey? Bear cub startles Oregon drugstore shoppers. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Dances With Wolves in China's Wild West

Dances With Wolves in China's Wild West

AFP (Oct. 23, 2014) One man is on a mission to boost the population of wolves in China's violence-wracked far west. The animal - symbol of the Uighur minority there - is under threat with a massive human resettlement program in the region. Duration: 00:41 Video provided by AFP
Powered by NewsLook.com
Breakfast Debate: To Eat Or Not To Eat?

Breakfast Debate: To Eat Or Not To Eat?

Newsy (Oct. 23, 2014) Conflicting studies published in the same week re-ignited the debate over whether we should be eating breakfast. 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:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

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