Key points from article :
Bacteria created that mops up excess ammonia in the body.
Engineered to control how they operate in the human gastrointestinal tract.
High levels can be fatal for people with liver damage and rare genetic disorders.
Microbes boosted survival rates in susceptible mice.
Small trial in healthy people found the bacteria were safe to take.
Developed by Synlogic which was co-founded by MIT.
Technique could also be used to produce something beneficial for the patient.
The study was published in Science Translational Medicine journal.