Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Detection of Salmonella in 24 hours

09.02.2007
The food and drink we consume have to pass strict quality controls. Nevertheless, these measures are not always sufficient, given that sometimes certain foodstuffs can still give rise to food poisoning, most often caused by micro-organisms.

The Salmonella bacterium is undoubtedly one of the best known of these. At the University of the Basque Country (UPV/EHU) they are developing a new, rapid-detection system (within 24 hours) for Salmonella.

It is currently a laborious process to detect Salmonella in food. An analytical study is carried out in the laboratory by means of conventional microbiological techniques and the results take a week, a delay which creates problems for the food industry

In 2002 the Department of Immunology, Microbiology and Parasitology at the UPV/EHU together with the company, Laboratorios Bromatológicos Araba, and the Leioa Technological Centre, decided to carry out collaborative work in order to try to develop new, faster methods for Salmonella detection.

... more about:
»DNA »RNA »Salmonelle »UPV/EHU »enable

Genetic methods

A requisite for such genetic methods is to know the genome of this bacterium well. Fortunately there are several strains of Salmonella which have been totally sequenced. It is also known that there are certain genes that are specific to Salmonella that are not found in any other bacteria nor, for that matter, in any other living being. Thus, if we detect these genes, it means the presence of Salmonella. Although we may not detect the entire micro-organism, we can find the DNA of this bacteria.

The study of this DNA has given rise to technical developments which enable the detection of the presence or absence of Salmonella within 24 hours in food. Nevertheless, these methods based on the detection of DNA have a drawback. DNA is a very stable molecule that enables its study in persons who have died many years before. The same can happen in bacteria, i.e. it may be that we are identifying the DNA but that the bacteria have been destroyed by pasteurisation or sterilisation. The researchers have shown that the detection of the DNA in itself is not sufficient to identify the Salmonella given that, using this technique, it is not possible to know if the bacterium is dead or alive.

So the UPV/EHU found another, more specific marker for the viability of the bacteria – messenger RNA; an unstable and easily degradable molecule which is only produced when the bacteria is in the multiplication phase (and thus capable of producing infection), and is subsequently destroyed. Armed with this knowledge, the UPV/EHU research team designed a procedure to extract this RNA from foodstuffs, with subsequent transformation of this RNA into DNA and the detection of the latter.

Working with RNA means working with great precision and speed, because it can give us false negative results, i.e. indicate that there is no salmonella when, in fact, there is, the molecule having degraded. The extraction procedure is a fundamental one: once the messenger RNA is extracted, it is transformed into DNA by means of inverse transcription; a process whereby a DNA copy is synthesised. This DNA copy is detected by certain probes previously developed by the research team. In fact, the probes are DNA chains that are complementary to Salmonella genes marked with a fluorescent compound. If the DNA copy and the complementary DNA unite, the fluorescent compound emits a signal detectable in real time. This device, moreover, enables the quantification of the reaction, i.e. it tells us the number of Salmonella cells present in the food sample.

What the UPV/EHU researchers are proposing, in fact, is a combination of techniques: extraction on the one hand; the design of probes for and detection of DNA and RNA molecules on the other. They are techniques complementary to the traditional cell cultures and that enable the analysis of more samples in less time, thus enhancing food safety globally.

Irati Kortabitarte | alfa
Further information:
http://www.basqueresearch.com/berria_irakurri.asp?Gelaxka=1_1&Berri_Kod=1181&hizk=I

Further reports about: DNA RNA Salmonelle UPV/EHU enable

More articles from Life Sciences:

nachricht Newly designed molecule binds nitrogen
23.02.2018 | Julius-Maximilians-Universität Würzburg

nachricht Atomic Design by Water
23.02.2018 | Max-Planck-Institut für Eisenforschung GmbH

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Good vibrations feel the force

A group of researchers led by Andrea Cavalleri at the Max Planck Institute for Structure and Dynamics of Matter (MPSD) in Hamburg has demonstrated a new method enabling precise measurements of the interatomic forces that hold crystalline solids together. The paper Probing the Interatomic Potential of Solids by Strong-Field Nonlinear Phononics, published online in Nature, explains how a terahertz-frequency laser pulse can drive very large deformations of the crystal.

By measuring the highly unusual atomic trajectories under extreme electromagnetic transients, the MPSD group could reconstruct how rigid the atomic bonds are...

Im Focus: Developing reliable quantum computers

International research team makes important step on the path to solving certification problems

Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Newly designed molecule binds nitrogen

23.02.2018 | Life Sciences

Stagnation in the South Pacific Explains Natural CO2 Fluctuations

23.02.2018 | Earth Sciences

Mat4Rail: EU Research Project on the Railway of the Future

23.02.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>