Engineers from MIT have combined bacterial cells with inorganic elements to create a remarkable new form of “living” functional material.

The engineers have tinkered with commonplace bacteria to produce biofilms which can be integrated with non-organic materials, potentially conferring them with remarkable properties including heightened conductivity, sensing capabilities, and the ability to alter their own composition.

The MIT engineers used the E.coli bacterium, more commonly associated with minor bouts of food poisoning, to manufacture biofilms harbouring an abundance of "curli fibres" - amyloid proteins which enable the intestinal microorganisms to better cling to surfaces.

These curli fibres are the key to incorporating inorganic elements into the biofilm, as well as endowing it with an extraordinary range of capabilities. By programming the genes of the bacteria to produce varying types of curli fibres under specific conditions, the MIT scientists were able to adjust the properties of the biofilm with remarkable results.

The re-programmed cells can produce biofilms traversed by gold nanowires or speckled with quantum dots, as well as biofilms capable of conducting electricity, or even altering the very nature of its basic composition.

Timothy Lu

Timothy Lu

"It's a really simple system but what happens over time is you get curli that's increasingly labeled by gold particles," said Timothy Lu, assistant professor of electrical engineering and biological engineering at MIT, as well as senior author of a paper on the materials published in Nature Material. "It shows that indeed you can make cells that talk to each other and they can change the composition of the material over time."

Lu said the final goal of the MIT engineers is to develop artificial materials which possess all the sophistication and independent adaptivity of organic matter.

"Our idea is to put the living and the nonliving worlds together to make hybrid materials that have living cells in them and are functional," he said. "Ultimately we hope to emulate how natural systems, like bone, form. No one tells bone what to do, but it generates a material in response to environmental signals."

According to Lu, the living functional material harbours tremendous potential for the energy sector, particularly for the development of new types batteries and solar cells.

The material could also be used to facilitate the conversion of agriculture waste matter into biofuels, by expediting the breakdown of cellulose via the incorporation of enzymes onto the surface of the biofilm.