27 May 2015
Vol 7, Issue 289

About The Cover

Cover image expansion

ONLINE COVER Bug-Based Biosensors. Shown is a bacterium as imagined by a synthetic biologist—as a living tool with insides akin to a printed circuit board, which can be rewired to perform a variety of desired functions. With their natural ability to detect biomolecules, process signals, and respond, bacteria are clear candidates for biosensing devices. Two research articles in this issue describe bug-based biosensors that serve as diagnostic tools. Courbet et al. engineered bacteria to serve as whole-cell diagnostic biosensors in complex human biological samples. Danino et al. designed a strain of Escherichia coli that produces β-galactosidase, an enzyme that metabolizes an artificial substrate to yield luciferin, which is easily detectable in urine. When mice were fed the engineered bacteria, they traveled to the liver and lodged in tumor colonies. The amount of luciferin in the urine reflects the tumor burden in the liver. [CREDIT: V. ALTOUNIAN/SCIENCE TRANSLATIONAL MEDICINE]