Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Team jams bacteria ’talk’ to boost bio-product yields

06.05.2003


In studies that could be vital to an expanding field of industrial biotechnology, scientists at the Center for Biosystems Research are learning to censor what E.coli bacteria are ’talking’ about.

Cell-to-cell cross talking by laboratory E. coli strains engineered to produce antibiotics, industrial polymers or other products in fermentation vessels can lead to stress in the culture and severely limit product output. But scientists with CBR and partners have begun to decipher and override stress ’talk’ among cells of recombinant E. coli. CBR is part of the University of Maryland Biotechnology Institute (UMBI).

In separate fermentation experiments with strains of E. coli that produce two important model products--interleukin-2 or organophosphorus hydrolase--the team increased product output by three to four times. The first product is an important drug in preventing cancer and HIV. The latter is a detoxifying agent for biowarfare nerve agents.



The scientists achieved higher yields of both products by either conditioning the bacterial cultures with high levels of molecules from a signaling pathway called AI-2, or by splicing the LuxS gene for quorum signaling into the recombinant E. coli.

"This is great," says team leader William Bentley, CBR research professor. "We want to understand what are the receptor molecules on these cells, to understand the communication circuitry," he adds. The experimental techniques are applicable to boosting production of many other products in E. coli cultures. However, the researchers say they are only beginning to understand and control the communications circuitry of E. coli and other bacterial cells.

E. coli is a common enteric bacterium that is one of the most highly studied microbes, with its genome and basic physiology well known. It is also one of the easiest vehicles for genetic engineering and a workhorse for metabolic engineering, an emerging branch of industrial biotechnology. Metabolic engineers study interactions of biological molecules in order to improve the manufacture of cell products and proteins for therapeutic and industrial value.

At CBR, Bentley heads one of a very few metabolic engineering laboratories focused on non-pathogenic E. coli quorum sensing. "We first learned that when you grow E. coli in a fermentor, the resulting product per cell goes down to a third of what it was (on the laboratory bench), but you still make more cells. Why don’t they make as much at high cell density as low cell density? We decided to look at what changes are going on." The team also includes Matthew P. DeLisa, formerly of Bentley’s laboratory and currently with Cornell University; and James J. Valdes, U.S. Army Soldier & Biological Chemical Command, Aberdeen Proving Grounds, Md.

Scientists have known about chemical cross-talking among cells of bacteria since 1970. Through such communication, bacteria gauge their own population density and respond by altering their expression of specific genes as a group, a process known as quorum sensing. In marine microbes, quorum-sensing molecules speed up reproduction to form bio-fouling films that may colonize on surfaces of boats or piers. Pathogenic bacteria, such as those that cause cholera, salmonella, Lyme disease, tuberculosis and pneumonia, become virulent. Still others such as Anthrax may form spores when they reach a quorum, or make antibiotics to fight off neighboring microbes.

But studies of cell-to-cell ’talking’ in E. coli, so important to industrial biotechnology, have lagged behind somewhat. Scientists at Princeton University discovered signaling molecules in E. coli in 1998.

Bentley’s team is investigating recombinant E. coli in the context of "an emerging centralized role for quorum sensing where it overlaps with signals for stress and starvation," he says. This new link between quorum sensing, cellular metabolism and stress-responsive circuits raises the possibility of targeting quorum pathways for improving cellular productivity.

They observed that signaling in recombinant E. coli, decreased the yields of a desired protein product. There had been no previously published reports of experiments to use quorum-sensing signaling pathway molecules or genes to improve recombinant protein yield in any bacteria expression system.

The team began two years ago by mapping DNA transcription of four quorum-regulated genes and 20 stress genes of E. coli. They found significant regulatory overlap among several stress and starvation genes and known quorum-sensing genes. "Because quorum-sensing signals turn bacterial genes on and off, deciphering this language will enable us to commandeer it for our own purposes, like controlling protein and metabolic engineering, rewiring cells, you might say, to produce important polymers or try to figure out the coordination of the enzymatic pathways. This is just the very beginning."

Such biological processing (fermentation) to produce products is more desirable than traditional industrial processing because of the use of renewable resources such as E. coli bacteria. It is more energy efficient and cleaner processing.


Researcher e-mails: bentley@eng.umd.edu, delisa@che.utexas.edu.

The University of Maryland Biotechnology Institute was mandated by the state of Maryland legislature in 1985 as "a new paradigm of state economic development in biotech-related sciences." With five major research and education centers across Maryland, UMBI is dedicated to advancing the frontiers of biotechnology. The centers are the Center for Advanced Research in Biotechnology in Rockville; Center for Biosystems Research in College Park; and Center of Marine Biotechnology, Medical Biotechnology Center, and the Institute of Human Virology, all in Baltimore. To license UMBI technology, contact Technology Transfer Director Rita Khanna, 410.385.6324.

Steve Berberich | EurekAlert!
Further information:
http://www.umbi.umd.edu/

More articles from Life Sciences:

nachricht Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY

nachricht NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Future electronic components to be printed like newspapers

A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.

The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

A smart safe rechargeable zinc ion battery based on sol-gel transition electrolytes

20.07.2018 | Power and Electrical Engineering

Reversing cause and effect is no trouble for quantum computers

20.07.2018 | Information Technology

Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern

20.07.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>