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Novel method uses nanobiotechnology to kill pathogens instead of antibiotics or chemicals

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By Joe Whitworth+

03-Apr-2013
Last updated the 03-Apr-2013 at 12:28 GMT

Researchers attached cell lytic enzymes to food-safe silica nanoparticles and created a coating (seen in this scanning electron micrograph). Photo Credit: Rensselaer/Dordick

Researchers attached cell lytic enzymes to food-safe silica nanoparticles and created a coating (seen in this scanning electron micrograph). Photo Credit: Rensselaer/Dordick

Nanobiotechnology incorporating enzymes and nanoparticles is an alternative to antibiotics and chemicals in the battle against foodborne disease, according to research.

Researchers from Rensselaer Polytechnic Institute attached cell lytic enzymes to food-safe silica nanoparticles, and created a coating with the ability to selectively kill listeria in food handling and packaging.

The coating kills listeria on contact, even at high concentrations, within a few minutes without affecting other bacteria, said Solanki et al.

Enzymes and nanoparticles

To stabilize the listeria-killing lytic enzymes, called Ply500, the researchers attached them to silica nanoparticles to create an ultra-thin film.

They also used maltose binding protein to attach Ply500 to edible starch nanoparticles used in food packaging.

Both Ply500 formulations were effective in killing within 24 hours all listeria at concentrations as high as 100,000 bacteria per milliliter—a higher concentration than found in food contamination situations.

The method was evaluated on iceberg lettuce leaves with results showing the complete killing of listeria under certain parameters.

Ravi Kane, the P.K. Lashmet professor of chemical and biological engineering, said in the study they have identified a new strategy for selectively killing specific types of bacteria.

“Stable enzyme-based coatings or sprays could be used in food supply infrastructure—from picking equipment to packaging to preparation—to kill listeria before anyone has a chance to get sick from it.”  

Antibiotic and chemical use

Treatment of listeriosis is feasible with antibiotics but overuse can lead to resistance.

Chemical and physical decontamination strategies currently include those based on using hydrogen peroxide, quaternary ammonium compounds, bleach, sodium or potassium lactate, hot water washes and others.

These methods cannot be used on foodstuffs directly, and the corrosiveness of most chemical decontaminants limits their use and effectiveness in the food infrastructure, said the researchers in the study supported with funding from Sealed Air Corporation.

Linda Schadler, the Russell Sage Professor and associate dean for academic affairs for the Rensselaer School of Engineering, said starch is an inexpensive, edible material often sprayed into the packaging as a powder layer on meat product.

“We took advantage of the natural affinity of a maltose binding protein fused to Ply500, and biologically bound Ply500 to starch as a non-antibiotic, non-chemical agent for reducing the threat of listeria to our food supply.”

The study builds on the 2010 development of creating a coating for killing methicillin resistant Staphylococcus aureus (MRSA) for use on surgical equipment and hospital walls.

Source: Scientific Reports

Online, ahead of print, doi: 10.1038/srep01584

Enzyme-Based Listericidal Nanocomposites”

Authors: Kusum Solanki, Navdeep Grover, Patrick Downs, Elena E. Paskaleva, Krunal K. Mehta, Lillian Lee, Linda S. Schadler, Ravi S. Kane and Jonathan S. Dordick

1 comment (Comments are now closed)

'Food -safe' nano particles?

I am certain I missed something. When were the silica nano particles deemed 'food- safe'? There seems to be a trend that relies increasingly on potentially dangerous high-tech solutions to solve food safety problems that should be handled by good manufacturing practices.

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Posted by mark
03 April 2013 | 16h55