IISc finds way to turn fatty acids into biofuels

The team then added another enzyme called catalase to the reaction mix.
Indian Institute of Science (IISC) in Bengaluru
Indian Institute of Science (IISC) in BengaluruFile photo| EPS

BENGALURU: Researchers at the IISc have developed a special enzyme system that turns inexpensive fatty acids into valuable biofuels called 1-alkenes, hydrocarbons. These 1-alkenes can be blended with existing fuels, making them a promising sustainable option.

According to scientists, hydrocarbons have potential as ‘drop-in’ biofuels, which can be blended and used with existing fuels and infrastructure. These can potentially be synthesised on a large scale using microorganism factories. Hydrocarbons are also widely used in polymer, detergent and lubricant industries.

In an earlier study, the IISc team purified and characterised an enzyme called UndB, bound to the membranes of living cells, especially certain bacteria. It can convert fatty acids to 1-alkenes at the fastest rate currently possible. However, the researchers found that the process was not very efficient – the enzyme would become inactivated after just a few cycles. When they investigated further, they realised that H2O2 – a byproduct of the reaction process – was inhibiting UndB.

The team then added another enzyme called catalase to the reaction mix. “The catalase degrades the H2O2 that is produced. Which enhanced the activity of the enzyme 19-fold, from 14 to 265 turnovers (turnover indicates the number of active cycles an enzyme completes before getting inactivated),” explained Tabish Iqbal, first author of the study and PhD student at the Department of Inorganic and Physical Chemistry.

“The team decided to create an artificial fusion protein combining UndB with catalase, by introducing a fused genetic code via carriers called plasmids into E. coli bacteria. Given the right conditions, these E. coli would then act as a ‘whole cell biocatalyst’, converting fatty acids and churning out alkenes,” read an IISc release.

A key advantage of this biocatalyst is that UndB is very specific and does not produce any unwanted side products – pure 1-alkene is the only product which can directly be used as biofuels, said Debasis Das, Assistant Professor at IPC and corresponding author.

The team has applied for a patent for their engineered protein and whole-cell biocatalyst. They are also looking for industry collaborators to scale up the platform for mass production. “Our platform can be efficiently used to generate a large number of 1-alkenes, valuable in biotechnology and polymer industries,” said Das.

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