In a collaborative effort that yielded two papers in the journal Nature, researchers from Harvard Medical School and Yale University have inserted new codons into bacteria to produce synthetic amino acids that will drive functions essential for farming use, without relying on divisive Genetically Modified Organism (GMO) technology.
GMOs are “any living organism that possesses a novel combination of genetic material obtained through the use of modern biotechnology”, as per the Cartagena Protocol on Biosafety. As it relates to crops and animals (particularly fish) for human consumption, the GMO issue becomes contentious, owing mainly to the public’s distrust of science and ignorance of the safe engineering technology. Bacteria are often genetically modified because of the ease of manipulation, and this has led scientists to attempt to devise ways to incorporate useful bacterial genes into crop productions. For example, the endotoxin of the bacteria Bacillus thuringiensis has been used as a natural insecticide in crops.
But the public and policy makers are still worried that crops with these bacterial genes will cause disease in humans, leaving many promising therapies on the shelf. To combat this, the researchers chose to design bacterial proteins that rely on synthetic amino acids designed in the laboratory, therefore rendering the bacteria unable to propagate in the wild.
The researchers started by inserting a simple three base-pair codon into a functional protein of Escherichia coli that codes for an amino acid not found in nature. These “genetically recoded organisms” (GROs) eventually evolved to preferentially use this amino acid in protein construction. Further synthetic amino acid additions to other proteins and further rounds of evolution led to the GROs being dependent on this synthetic amino acid for growth and division.
When put into the wild, the GROs died as they were unable to use normal amino acids to make the proteins for their proper functions. The bacteria were also unable to pass along their genes through homologous recombination and horizontal gene transfer. This method will “lead to tremendous stringencies in terms of biocontainment,” said Dieter Söll, a Yale chemist who works on recoding organisms. Many groups have argued that GMOs will escape the confines of their given farm and populate the wild with laboratory developed gene manipulations.
Dr. Farren Isaacs of Yale was optimistic about this new technology: ““It really addresses a long-standing problem in biotechnology, by engineering a really compelling solution to engineering biocontainments or biological barriers that limit the spread and survival of organisms in natural environments, and along the way also endow these organisms with new and expanded biological function.”
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