An engineered bacterium can deliver a therapeutic protein straight to the gut when fed with xylan.Could genetically-engineered bacteria help to banish gastrointestinal woes?Punchstock A gut-dwelling bacterium has been genetically engineered to deliver a dose of therapeutic protein on demand.Protein production in the engineered bacterium is switched on only when its host eats the complex sugar xylan. Tests on mice that had colonies of the bacteria in their guts showed that the expressed protein can successfully treat an inflammatory bowel disease called colitis.The research, to be published in the journal Gut1, has potential as an alternative method for delivering drugs to...