In a study reported in the online edition of Science on Aug. 10, 2023, a group of synthetic biologists from the University of California (UC) San Diego and clinicians from Australia have engineered synthetic bacteria to detect specific DNA sequences in the genomes of colorectal cancer (CRC) cells and organoids. This living cell sensor capable of detecting cancer in the colons of mice has the potential to steer the way to new biosensors capable of identifying various infections, cancers and other diseases.