12 January - 20 June 2016

GE plants produce proteins able to reduce E. coli on food

23 September 2015

A team of scientists is genetically engineering plants to produce antimicrobial proteins known as colicins, which can then be extracted and applied to contaminated meat and produce to kill E.coli bacteria. E.coli is one of the leading causes of bacterial enteric infections worldwide, causing 100,000 illnesses, 3,000 hospitalisations and 90 deaths in the United States alone. These illnesses have been linked to consumption of contaminated animal products and vegetables. Currently, other than thermal inactivation, there are no effective methods to eliminate pathogenic bacteria in food. 

In the current study published in the Proceedings of the National Academy of Sciences, the researchers engineered tobacco, leafy beets, spinach, chicory and lettuce to produce colicins. Colicins are naturally produced nonantibiotic antimicrobial proteins, produced by E.coli strains that kill or inhibit growth of other competing E.coli strains. The proteins are extremely toxic, so the researchers decided to engineer the aforementioned plants since colicins are not as toxic to plant cells. In the study, the researchers sprayed E.coli-laced pork steaks with a mixture of two types of colicins and found significant reductions in E.coli after just one hour. One of the authors of the study added that colicins are 50 times more active against bacteria than normal antibiotics. The team also hired a third party to do an economic analysis of their process and found that the method competes with decontamination methods, such as acid washes and heat processing, currently favoured by the meat industry. 

To conclude, plant-produced colicins could be effectively used for the broad control of pathogenic E.coli in both plant and animal-based food products, and research team members are planning to extend their process to other bacteria such as Salmonella.

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