Dancing to the beat of bacteria: Forging gel-material in bacterial baths

 

Image: Bacteria with flagellum (Source: Yutaka Tsutsumi, Fujita Health University School of Medicine http://info.fujita-hu.ac.jp/~tsutsumi/photo/photo002-6.htmhttp://info.fujita-hu.ac.jp/~tsutsumi/image/002/2-6.jpg, Copyrighted free use, https://commons.wikimedia.org/w/index.php?curid=535442)
 

Scientists from the Institute of Science and Technology Austria, have created a bath of swimming bacteria to assemble unconventional materials, based on the energy of swimming bacteria to forge the materials.

 

The novel experimental strategy is designed to fabricate materials from small building blocks. Inspired by metallurgy, where cycles of high temperature and slow cooling set a material's structure, the process has been applied to the creation of soft materials.

 

The process begins using building blocks that are a hundred times smaller than a hair. A major part of the research is to understand how these components come together and form larger structures.

 

The building blocks are suspended in water, and they move due to temperature, which provides the energy for the particles to hop back and forth randomly (Brownian motion). By adding bacteria to the bath, an "active bath" is created, and additional energy is provided. By controlling the bacterial numbers, an element of control is provided to the assembly and properties of materials.

 

E. coli

In the study Escherichia coli was used as an active agent. The swimming movement of these motile bacteria provided energy and some kind of agitation. This enabled round colloidal beads to stick together to form a gel.

 

Further analysis showed the importance of singularity. The slow and persistent rotation of the aggregates was riven by the clockwise spin (chirality) of the E. coli flagella. This was first realised through the use of computer simulations.

 

Such bacteria swim using a bundle of flagella (flexible hair-like structures) that form a rotating corkscrew of chiral shape, where each flagellum is actuated by a molecular motor at the bacterial surface.

 

The first studies were conducted on forming 2D structures at the micron scale. The researchers next plan to upscale this to construct 3D samples, large enough to be held in the palm of a hand.

 

A further advantage is that the process could enhance the sustainability of material production by harnessing energy from bacteria rather than relying on external energy sources.

 

The research appears in the journal Nature Physics, titled “Unconventional colloidal aggregation in chiral bacterial baths.”

 

Posted by Dr. Tim Sandle, Pharmaceutical Microbiology Resources (http://www.pharmamicroresources.com/)