Scientists engineered a bacterium that can produce useful chemicals from industrial waste

It’s commonly known that microbes such as bacteria are used in the production of products like yogurt and bread. However, it’s less known that bacteria can be incredibly useful for producing industrial chemicals such as acetone, a powerful solvent with wide uses in the chemical industry. In the chemical industry, using bacteria and other microbes for producing commodity chemicals is relatively new. With the rise of the petroleum industry, by the 1960’s most chemical producers preferred petroleum over other alternatives for chemical production because it was a cheap starting material. Today, there is precedent for microbes such as yeast and E. coli being used for producing ethanol and acetone, but they require a significant amount of farmland to feed on. This has motivated research into engineering microbes that can feed on industrial waste and produce useful chemicals.

In the 1990's scientists began researching ways to genetically engineer a specific strain of bacteria of the Clostridium genus. The clostridium genus includes a lot of well known human pathogens including the bacteria responsible for botulism and tetanus. While these strains can be quite deadly, through genetic modification, scientists are able to carefully manipulate these bacteria to synthesize useful chemicals. We can think about bacteria as chemical synthesizing machines. They feed on a chemical or gas and transform that food into useful energy through processes such as fermentation. The scientists were able to engineer a bacteria called Clostridium autoethanogenum (C. Auto) that fed on carbon monoxide and hydrogen gas and produced acetone. 

Photo of Clostridium botulinum, the bacteria responsible for the development of botulism.

Recently, researchers were able to genetically engineer a collection of C.Auto to produce acetone more efficiently and on a larger scale than ever before. They first extracted enzymes that are important for acetone synthesis from other Clostridium bacteria. Then, they sequenced the genes of 30 of these enzymes and inserted them into the plasmids of C.auto, circular stands of stray DNA that can be used to transfer genetic material between bacteria. With this new sequence of instructions, scientists were able to produce C.auto strains that could convert steel waste gases into acetone and isopropanol on an industrial scale.

This research has huge implications for the future of waste management and provides a method for reducing carbon emissions. Using a similar procedure above, researchers are already looking into other microbes that can be engineered to feed on solid waste. This can help with cleaning out landfills or getting rid of agricultural waste. In addition, if other microbes can be produced to feed on carbon-based waste gas, then they can help reduce carbon pollution.