Leveraging on bacteria to build sensors

Roberto Saracco October 17, 2017 Blog 284 Views

A sea shell of the murex pecten that I saw at a friend’s home. Image credit: Nauti Shell Company

Living beings are amazing builders: they build themselves in many ways, mixing organic and inorganic substances to create constructions that are extremely well suited to fit and operate in a given environment. More than that: they do that using very little energy, far less than what we would use with our sophisticated machines.

I was shown just few days ago at a friend’s home a new shell he got and we wondered how could a simple animal (at least that is how we thought about it) build such a fantastic structure. It is all coded in its genes, molecule by molecule it builds that amazing structure capturing what it needs in its environment and assembling it in just the right way.

Now I run into a paper on Nature Biotechnology where researchers are reporting on their way to program bacteria to steer them into building a pressure sensor.

Bacteria create a functioning 3D pressure-sensor device. A gene circuit (left) triggers the production of an engineered protein that enables pattern-forming bacteria on growth membranes (center) to assemble gold nanoparticles into a hybrid organic-inorganic dome structure whose size and shape can be controlled by altering the growth environment. In this proof-of-concept demonstration, the gold structure serves as a functioning pressure switch (right) that responds to touch. Credit: Yangxiaolu Cao et al./Nature Biotechnology

The researchers, working at Duke University, have programmed bacteria to self assemble capturing certain molecules resulting in the creation of a pressure sensor. There have been in the past several studies and experiments using bacteria to build specific structures but so far this was achieved through an external control of the bacteria. Here they have programmed the bacterial genes so that the bacteria can work autonomously in the creation of the desired object.

The only external control is the access to nutrients (they decide what the bacteria has available). Notable, with previous experiments, bacteria operated on a flat surface, so that they can be controlled, producing 2D structures. Here the bacteria, operating on their own, can build 3D structures.

Another interesting twist is that bacteria could remain part of the object created (providing a means to maintain a suitable environment for them to live) and then they can work to repair the object in case of need.

Clearly we are in a research space, pretty far from industrialisation but it is extremely interesting to observe the increasing capabilities we are acquiring in steering life. This is also going in the direction of reinforcing the trend towards symbiotic autonomous systems since it will become possible to “engineer” the interfaces and behaviour of part of the components participating in the symbioses.