Engineered bacteria make fuel from sunlight

In a bid to find a substitute to fossil fuels as raw material for the chemical industry, scientists have engineered bacteria, which could help grow chemical precursors for fuels and plastics.

"Most chemical feed stocks come from petroleum and natural gas, and we need other sources," assistant professor of chemistry at University of California, Davis and lead author on the study Shota Atsumi said.

Biological reactions are good at forming carbon-carbon bonds, using carbon dioxide as a raw material for reactions powered by sunlight, called photosynthesis, and cyanobacteria, also known as "blue-green algae," have been doing it for more than 3 billion years, the Science Daily reported.

The challenge is to get the cyanobacteria to make significant amounts of chemicals that can be readily converted to chemical feed stocks.

With support from Japanese chemical manufacturer Asahi Kasei Corp., Atsumi's lab at UC Davis has been working on introducing

new chemical pathways into the cyanobacteria.

The researchers, working a step at a time, built up a three-step pathway that allows the cyanobacteria to convert carbon dioxide into 2,3 butanediol, a chemical that can be used to make paint, solvents, plastics, and fuels.

"Because enzymes may work differently in different organisms, it is nearly impossible to predict how well the pathway will work before testing it in an experiment," Atsumi said.

After three weeks growth, the cyanobacteria yielded 2.4 grams of 2,3 butanediol per liter of growth medium - the highest productivity yet achieved for chemicals grown by cyanobacteria and with potential for commercial development, Atsumi added.

Atsumi hopes to tune the system to increase productivity further and experiment with other products, while corporate partners explore scaling up the technology.

The US Department of Energy has set a goal of obtaining a quarter of industrial chemicals from biological processes by 2025.

The study was published in the journal Proceedings of the National Academy of Sciences.