Synthetic biology—our attempt to engineer living organisms—has put a lot of effort into making genetic circuitry mimic what we do in silicon. Logical gates, amplifiers, and more have all been implemented using DNA and proteins. While these feats of genetic engineering have been impressive, how we’d put these genetic circuits to use hasn’t always been clear. It’s easy to imagine a logical gate in a bacteria would be useful for various biotechnology applications, but there haven’t been many opportunities when someone put one to use.

An exception to this was reported in this week’s edition of Nature Biotechnology. A team at Duke University has engineered a bacterial population that uses engineered genetic circuitry to express a protein only in specific locations. The researchers then printed these bacteria onto a surface and processed them to coat the protein in gold. The result is a tiny gold dome that makes a great pressure sensor.

Bacterial circuitry

The circuit itself is interesting in its own right. One part of it is pretty simple: a gene encodes a protein that feeds back to the gene itself, making sure it’s active. Thus, once this gene becomes activated, it stays activated unless something else happens.