A research team led by Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California, Berkeley, has engineered bacteria to produce new carbon products to nature that could provide a powerful route to sustainable biochemicals.
Progress – which was recently announced in the journal nature – Uses bacteria to combine natural enzymatic reactions with a new-to-nature reaction called a “carbyne transfer reaction”. This work could also one day help reduce industrial emissions as it provides sustainable alternatives to chemical manufacturing processes that typically rely on fossil fuels.
“What we’ve shown in this paper is that we can synthesize everything in this reaction – from natural enzymes to carbines – inside the bacterial cell. All you need to add is sugar and the cells will do the rest,” said Jay Keasling. The study’s principal investigator and CEO of the Department of Energy’s Joint Bioenergy Institute (JBEI).
Carbenes are highly reactive carbon-based chemicals that can be used in many different types of reactions. For decades, scientists have wanted to use carbene reactions in the manufacture of fuels and chemicals, and in drug discovery and manufacture.
But these carbene processes can only be done in small batches via test tubes and require expensive chemicals to get the reaction moving.
In the new study, researchers replaced expensive chemical reactants with natural products that could be produced by an engineered strain of bacteria. streptomyces. Because bacteria use sugar to produce chemical products through cellular metabolism, “this work allows us to perform carbene chemistry without toxic solvents or toxic gases typically used in chemical synthesis,” said first author Jing Huang, a postdoctoral researcher at Berkeley Lab. in Keasling. laboratory. “This biological process is much more environmentally friendly than the way chemicals are manufactured today,” Huang said.
During experiments at JBEI, the researchers observed the engineered bacteria as they metabolized and converted sugars into a carbene and an alkene substrate. The bacteria also expressed the evolved P450 enzyme that uses those chemicals to produce cyclopropane, high-energy molecules that can be used in the sustainable production of new bioactive compounds and advanced biofuels. “We can now perform these interesting reactions inside the bacterial cell. Cells produce all the reagents and cofactors, which means you can scale this reaction to very large scales” for mass manufacturing, Kiesling said.
Huang said that recruiting bacteria to manufacture chemicals could also play an essential role in reducing carbon emissions. According to other Berkeley Lab researchers, nearly 50% of greenhouse gas emissions come from the production of chemicals, iron, steel, and cement. Limiting global warming to 1.5°C above pre-industrial levels will require a drastic halving of greenhouse gas emissions by 2030, according to a recent report by the Intergovernmental Panel on Climate Change.
Huang said that while such a fully integrated system for a large number of carbene donor molecules and alkyne substrates can be conceived, it is not yet ready for commercialization.
“For every new advance, someone needs to take the first step. And in science, it can take years before it works. But you have to keep trying – we can’t afford to give up. I hope our work inspires others to keep looking for greener and more sustainable biofabrication solutions.” “.
This work was supported by the Department of Energy’s Office of Science and the Department of Energy’s Office of Biological and Environmental Research. Additional support was provided by the National Science Foundation.