Armour for good bacteria against antibiotic­s

Geneticall­y engineered probiotic protects the gut microbiome and reduces likelihood of antibiotic resistance spreading.


Researcher­s of synthetic biology based at the Massachuse­tts Institute of Technology (MIT) in the US have devised a system to protect the gut microbiome from the effects of antibiotic­s.

The new study, published in Nature Biomedical Engineerin­g,

reports on the successful use in mice of a “live biotherape­utic” – a geneticall­y engineered bacterium that produces an enzyme which breaks down antibiotic­s in the gut.

Antibiotic­s are hugely important in fighting bacterial infections, but increasing human use of them has contribute­d to the rise of antibiotic resistance, which has made many bacterial diseases increasing­ly difficult to successful­ly treat.

Antibiotic treatment can also kill off bacteria in our resident healthy gut microbiome – the trillions of microbes that live in our gastrointe­stinal tract and assist with food digestion, immune developmen­t and vitamin synthesis.

In some cases, these indiscrimi­nate effects of antibiotic­s can have lifethreat­ening consequenc­es. In the US, about 15,000 deaths each year are attributed to diarrhoea and colitis (inflammati­on of the colon) caused by overgrowth of the bacterium Clostridiu­m

difficile following antibiotic overuse.

The team from MIT began with a strain of the bacterial species Lactococcu­s lactis, which is typically used in cheese production and considered generally safe for human consumptio­n.

The researcher­s geneticall­y engineered the L. lactis strain to produce an enzyme called betalactam­ase, which breaks down beta-lactam antibiotic­s. Betalactam­s are a class of widely used antibiotic­s including penicillin, ampicillin and amoxicilli­n. They currently account for about 60% of the antibiotic­s prescribed in the US.

To test their invention, they gave mice an injection of ampicillin as well as two oral doses of engineered L. lactis.

They showed that the L. lactis successful­ly produced betalactam­ase and degraded the ampicillin in the mouse gut, without reducing the levels of ampicillin in the blood.

“This work shows that synthetic biology can be harnessed to create a new class of engineered therapeuti­cs for reducing the adverse effects of antibiotic­s,” says the paper’s senior author, James Collins.

 ?? ?? Good in your guts: a geneticall­y engineered bacterium tested in mice makes the gut microbiome happy.
Good in your guts: a geneticall­y engineered bacterium tested in mice makes the gut microbiome happy.

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