Now, more effective nisin antibiotics to fight food-borne superbugs, pathogens

March 31st, 2009 - 5:06 pm ICT by ANI  

Washington, Mar 31 (ANI): A new generation of natural antibiotics-called nisin variants-can now kill food bacteria and other pathogens that cause food-related diseases.

Bio-engineered by researchers at University College Cork, nisin can kill harmful micro-organisms such as MRSA and the food-borne pathogen, Listeria monocytogenes.

Nisin is an antimicrobial protein produced naturally by a bacterium called Lactococcus lactis.

The researchers explained how they altered different amino acids in nisin and created a family of variants, each slightly different from the naturally occurring protein.

The bioengineered nisin variants possessed greater activities than the parent molecule against a range of important clinical pathogens including MRSA, VRE (Vancomycin resistant Enterococci) and the food-borne pathogen Listeria monocytogenes.

Already, nisin is used as a natural biopreservative in heat-treated and low-pH foods. It has a long record of safe use and is one of only a few such compounds to have been applied commercially.

As antibiotic resistance has become a serious public threat, the scientists are hoping that these enhanced nisin variants could become acceptable alternatives to the range of antimicrobials currently available.

Using enhanced nisin variants against food-borne pathogens such as Listeria is particularly significant as this bacterium is among the most naturally nisin resistant pathogens.

Listeria monocytogenes usually causes illness in vulnerable groups-such as pregnant women, babies, the elderly and people with reduced immunity-whose illness is often severe and life threatening.

The bacterium has been found in a variety of raw foods, such as uncooked meats and vegetables, as well as in processed foods that become contaminated after processing such as soft cheeses and hot dogs.

Thus, scientists are working towards developing improved versions of nisin that specifically target Listeria, which could turn out to be a more preferable option than the current form of nisin for some food biopreservation applications.

“For example, Nisin has the potential to be a safer alternative due to its high antibacterial activity and nontoxicity to humans. The fact that different nisin derivatives can now be generated to target specific pathogenic organisms makes it even more attractive as a natural and potent antimicrobial for clinical and food use,” said the authors of the study.

They added: “It may also be possible to reduce the levels of other preservatives such as salt, sugar and certain chemicals often used in high concentrations to inhibit bacterial growth, ultimately leading to not only safe but healthier foods.”

The study was presented at the Society for General Microbiology meeting in Harrogate. (ANI)

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