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 Nanoparticle Exposure Can Awaken Dormant Viruses in the Lungs
16.01.2017 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt

nachricht Cholera bacteria infect more effectively with a simple twist of shape
13.01.2017 | Princeton University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

Im Focus: Bacterial Pac Man molecule snaps at sugar

Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.

The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

Water - as the underlying driver of the Earth’s carbon cycle

17.01.2017 | Earth Sciences

Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

17.01.2017 | Materials Sciences

Smart homes will “LISTEN” to your voice

17.01.2017 | Architecture and Construction

VideoLinks
B2B-VideoLinks
More VideoLinks >>>