Biochemical engineers from Nanyang Technological University in Singapore have genetically modified a strain of the Escherichia coli bacteria to fight Pseudomonas aeruginosa. By inserting DNA fragments into the E.coli, the engineered bacteria strain produced pyocin S5, a toxic protein which kills P.aeruginosa strains. Pyocins are produced by P.aeruginosa itself to compete with its own species, so they are species-specific antibiotics.
Next to this first enhancement, Matthew Chang and his team also engineered their E.coli strain to only release the pyocin when it detects P.aeruginosa bacteria. They exploited the organic chemical signaling cascade of P.aeruginosa and engineered their E.coli in such a way that it would only release pyocins when it detected the chemical signals that Pseudomonas bacteria send to each other.
P.aeruginosa is known to colonize the respiratory and gastrointestinal tract and can cause lethal infection in immunocompromised patients. This bacterium is also known to be resistant to many antibiotics and is one of the main bacterial causes of nosocomial infections. The authors wrote that they intended to develop a novel, unconventional antimicrobial strategy that does not rely on current antibiotics.
Tested on planktonic P.aeruginosa, the engineered E.coli sensed and killed the Pseudomonas bacteria and demonstrated a 99% reduction in the viable cells. In more virulent and antibiotic resistant P.aeruginosa biofilms it demonstrated a 90% reduction. The results seem promising for future studies in animal models. The engineers plan to refine their engineered E.coli to deliver greater amounts of pyocin upon release, before moving on to animal models. They also hope to extend their novel antimicrobial strategy to include pathogens such as Vibrio cholerae and Helicobacter pylori. It seems like the starting signal for the battle of the bacteria has been given.
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Abstract in Molecular Systems Biology: Engineering microbes to sense and eradicate Pseudomonas aeruginosa, a human pathogen