Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Study Provides New Means for Classifying E. coli Bacteria & Testing for Fecal Contamination

The meaning of the standard fecal coliform test used to monitor water quality has been called into question by a new study that identified sources of Escherichia coli bacteria that might not indicate an environmental hazard.

Fecal pollution of surface waters is measured by the concentration of E. coli bacteria in the water because E. coli is believed to live only in the intestines and waste of humans and other warm-blooded animals, and quickly die outside its host.

The presence of E. coli in water also serves as a marker for other potentially more harmful organisms that may accompany it. Positive E. coli tests may lead to the summertime closing of beaches and other recreational bodies of water.

In this new study, researchers report identifying and sequencing the genomes of nine strains of E. coli that have adapted to living in the environment independent of warm-blooded hosts. These strains are indistinguishable from typical E. coli based on traditional tests and yield a positive fecal coliform result though researchers say they may not represent a true environmental hazard.

“The basis for E. coli’s widespread use as a fecal pollution indicator is the traditional thinking that E. coli cannot survive for extended periods outside a host or waste, but this study indicates that’s not true,” said Kostas Konstantinidis, an assistant professor in the Georgia Tech School of Civil and Environmental Engineering. “These results suggest the need to develop a new culture-independent, genome-based coliform test so that the non-hazardous environmental types of E. coli are not counted as fecal contamination.”

A paper describing the research was published April 11 in the early edition of the journal Proceedings of the National Academy of Sciences. The work was sponsored by the National Science Foundation and the National Institutes of Health.

Konstantinidis and Georgia Tech School of Biology graduate student Chengwei Luo compared the genomes of 25 different strains of E. coli and close relatives, which were sequenced by the Center for Microbial Ecology at Michigan State University, the Broad Institute in Massachusetts, or were publicly available in the National Center for Biotechnology Information database. Nine strains that were recovered primarily from environmental sources encoded all genes required for classification as E. coli.

“The orders-of-magnitude higher abundances of the group of organisms represented by these nine strains in environmental samples relative to those in human feces and the clinic indicate that they represent truly environmentally adapted organisms that are not associated primarily with mammal hosts,” explained Konstantinidis, who also holds a joint appointment in the Georgia Tech School of Biology.

By comparing the full genomes of the samples, the Georgia Tech researchers identified 84 genes specific to or highly enriched in the genomes of the environmental E. coli and 120 genes specific to the strains commonly found in the gastrointestinal tract of healthy humans, which are called commensal E. coli. They also detected recent genetic exchange of core genes within the environmental E. coli and within the commensal strains, but not from commensal genomes to their environmental counterparts.

The environment-specific bacteria included genes important for resource acquisition and survival in the environment, such as the genes required to utilize energy sources and to break down dead cellular material. In contrast, the gastrointestinal E. coli included several genes involved in the transport and use of nutrients thought to be abundant in the gut.

“The genomic data suggest that the environmental E. coli are better at surviving in the external environment, but are less effective competitors in the gastrointestinal tract than commensal E. coli, which tells us that the environmental bacteria are highly unlikely to represent a risk to public health,” explained Konstantinidis.

Collectively, this data also indicates that the environmental E. coli strains represent a distinct species from their commensal E. coli counterparts even though they are identified as E. coli based on the standard taxonomic methods. This work is consistent with a more stringent and ecologic definition for bacterial species than the current definition and suggests ways to start replacing traditional, culture-based approaches for defining diagnostic phenotypes of new species with genomic-based procedures.

The scientific, medical, regulatory and legal communities expect species to reasonably reflect the traits and habitat of an organism -- especially an organism like E. coli that has ramifications for diagnostic microbiology and for assessing fecal pollution of natural ecosystems. Efforts toward a more refined definition of this bacterial species are needed, according to Konstantinidis.

This study’s findings provide a way to start redefining E. coli species and testing for fecal contamination with procedures based on genomics and ecology.

“We are now working to develop a molecular assay that uses the gastrointestinal-specific genes as robust biomarkers to count commensal E. coli cells in environmental samples more accurately than current methods,” added Konstantinidis.

This project is supported by a National Science Foundation (NSF) award to Georgia Tech and Michigan State University (Award No. DEB0516252) and a National Institutes of Health (NIH/NIAID) award to the Broad Institute (Award No. HHSN2722009000018C). The content is solely the responsibility of the principal investigators and does not necessarily represent the official views of NSF or NIH.

John Toon | Newswise Science News
Further information:

More articles from Studies and Analyses:

nachricht Diagnoses: When Are Several Opinions Better Than One?
19.07.2016 | Max-Planck-Institut für Bildungsforschung

nachricht High in calories and low in nutrients when adolescents share pictures of food online
07.04.2016 | University of Gothenburg

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

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

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

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

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>