Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A Bacteria and a Nematode: Natural Born Pest Killers

06.12.2004


In a world where 842 million people suffer from chronic hunger, insect pests consume 20-30 percent of world food crops. Chemical pesticides are increasingly expensive, ineffective and environmentally aggressive, killing beneficial insects and, when transmitted through the food chain, moving in unwanted directions.



The search for eco-friendly bio-insecticides has focused mainly on developing transgenic crops that express natural protein toxins. The most successful, by far, are crops that express the toxin from the bacterium Bacillus thuringiensis (BT). However the widespread use of BT transgenics has raised new—and contradictory—concerns; farmers fear the rapid evolution of BT-resistant insects and some consumers fear the rapid marketing of transgenic foods.

In the search for alternatives, scientists are revisiting a ‘natural’ biological control strategy used by insecticidal bacteria that live symbiotically with “entomopathogenic” nematodes. That’s a mouthful to describe an insect-killing bacterium that lives inside an unaffected worm host. The classic example is the bacterium, Xenorhabdus nematophila (X. nematophila; Latin for “loves nematodes”) and nematodes of the genus, Steinernema. Bacterium-nematode teams live almost their entire lifecycle inside larval-stage insects. The Xenorhabdus-Steinernema (‘X-S’) team is being used successfully to combat Lepidoptera, Coleoptera and Diptera pests.


Puneet Khandelwal, working with Prof. Rakesh Bhatnagar at the Centre for Biotechnology, Jawaharlal Nehru University, and Dr. Nirupama Banerjee at the International Centre for Genetic Engineering in New Delhi wanted to know why the X-S team was so deadly effective against one of the world’s costliest pests, Helicoverpa armigera (a.k.a. the scarce bordered straw moth). This moth’s larvae eat Zea mays, which is corn to Americans, maize to Europeans, and sustenance to millions in the Third World.

Khandelwal and colleagues succeeded in identifying the insecticidal factor. The active component was found in a large complex normally associated with the bacterial outer membrane, and was also present in or on outer membrane vesicles (OMVs) released from the bacterial surface, says Khandelwal. They then searched through OMV components and identified a small (17 kDa) toxic protein. When purified, this protein was toxic to cultured larval cells and directly killed H. armigera larvae. Gene cloning and sequencing showed this protein is related to a class of bacterial outer membrane proteins that form protrusions, called pili or fimbriae, which often help bacteria attach to host cells during infection. Similar to pili proteins, the purified 17 kDa protein self-associated to form oligomers, each of which was connected to the next by a strand. Most importantly, the recombinant 17 kDa protein killed H. armigera larvae, demonstrating its potential as a biological control agent in a world desperately in need of new ideas.

Insecticidal activity associated with a 17 kDa pilin protein of Xenorhabdus nematophila, P. Khandelwal,1 R. Bhatnagar,1 N. Banerjee2 ; 1 Centre For Biotechnology, Jawaharlal Nehru University, New Delhi, India, 2 Insect resistance, International Centre for Genetic Engineering and Biotechnology, New Delhi, India.

At the meeting: Session 329, Structure & Function of Membrane Proteins II, Poster Presentation 1726, Halls D/E. Author presents: Tuesday, Dec. 7, 1:30— 3:00 PM.

| newswise
Further information:
http://www.ascb.org

More articles from Life Sciences:

nachricht Fungi that evolved to eat wood offer new biomass conversion tool
25.07.2017 | University of Massachusetts at Amherst

nachricht New map may lead to drug development for complex brain disorders, USC researcher says
25.07.2017 | University of Southern California

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Carbon Nanotubes Turn Electrical Current into Light-emitting Quasi-particles

Strong light-matter coupling in these semiconducting tubes may hold the key to electrically pumped lasers

Light-matter quasi-particles can be generated electrically in semiconducting carbon nanotubes. Material scientists and physicists from Heidelberg University...

Im Focus: Flexible proximity sensor creates smart surfaces

Fraunhofer IPA has developed a proximity sensor made from silicone and carbon nanotubes (CNT) which detects objects and determines their position. The materials and printing process used mean that the sensor is extremely flexible, economical and can be used for large surfaces. Industry and research partners can use and further develop this innovation straight away.

At first glance, the proximity sensor appears to be nothing special: a thin, elastic layer of silicone onto which black square surfaces are printed, but these...

Im Focus: 3-D scanning with water

3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects

A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

 
Latest News

NASA flights gauge summer sea ice melt in the Arctic

25.07.2017 | Earth Sciences

Fungi that evolved to eat wood offer new biomass conversion tool

25.07.2017 | Life Sciences

New map may lead to drug development for complex brain disorders, USC researcher says

25.07.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>