Scientists are retooling bacteria to cure disease

Synlogic investigators have developed a bacterial concoction that may become the first synthetic biology-based medical treatment to gain FDA approval. By manipulating DNA, researchers are trying to design microbes that, once inside the body, work to treat a rare genetic disease called phenylketonuria (PKU).

Synlogic investigators have developed a bacterial concoction that may become the first synthetic biology-based medical treatment to gain FDA approval. By manipulating DNA, researchers are trying to design microbes that, once inside the body, work to treat a rare genetic disease called phenylketonuria (PKU). People with the condition must avoid dietary protein because they cannot break down an amino acid called phenylalanine. Synlogic researchers selected a harmless strain of E. coli and inserted genes into the bacteria's DNA so that once they arrived in the gut, they could break down phenylalanine like healthy people's cells do. The researchers wanted the microbes to break down phenylalanine only in the right place and at the right time, so they engineered the bacteria to keep their phenylalanine genes shut down if they sensed high levels of oxygen around them. Only when they arrived in the gut did they turn on their engineered genes. After Synlogic's bacteria showed promise in experiments on mice and monkeys, the company recruited healthy volunteers to swallow the bacteria and then ingest protein. On September 4, Synlogic announced that the trial had demonstrated people could safely tolerate the bacteria. Furthermore, the more bacteria they ingested, the more phenylalanine ended up in their urine—indicating the bacteria were doing their job. The researchers are now proceeding with a trial on people with PKU and expect to report initial results next year.