Researchers from the Indian Institute of Technology, IIT Guwahati, in collaboration with the University of Lisbon, Portugal, have found a bacterial endoglucanase enzyme capable of breaking down biomatter into simple sugar and bioethanol — a promising renewable fuel that can replace petroleum-based fuel systems.

The discovery has been published in the International Journal of Biological Macromolecules.

The production of fuel from renewable biological sources has attained significance in recent years because of the impending crisis of dwindling fossil fuel reserves and the environmental pollution associated with power generation from such sources.

The researchers demonstrated the efficacy of a new type of endoglucanase called RfGH5_4 in breaking down biomass for the eventual conversion to bioethanol fuel, which can be used for the efficient and cost-effective production of lignocellulosic bioethanol on an industrial scale.

Additionally, its ability to break down cellulose and hemicellulose makes it useful in various other applications such as the textile, food, and pulp industry, synthesis of prebiotics, and pharmaceuticals, among others.

The enzyme was derived from a bacterium called Ruminococcus flavefaciens.

Ruminococcus flavefaciens was chosen because this bacterium is found in the gut of cows and other cud-chewing animals, which has faced cellulosic pressure for millions of years.

The researchers developed an efficient machinery of RfGH5_4 to break down cellulose and cellulosic structures into simple sugars. The bacterium harbors a cohort of at least 14 different multimodular enzymes that can break down cellulose, one of which is RfGH5_4.

Arun Goyal, Department of Biosciences and Bioengineering, IIT Guwahati, said, “We characterized endoglucanase, RfGH5_4 and found that it hydrolyzed carboxymethyl cellulose (a lab-scale analog of cellulose) as well as normal amorphous cellulose with greater catalytic efficiency.”

The team’s earlier work on RfGH5_4 revealed that this endoglucanase is multifunctional and catalytically efficient.

Parmeshwar Gavande, Ph.D. research scholar and the lead author, elaborated, “RfGH5_4 was found to contain some highly flexible loops in its core structure, making room for different carbohydrate polymers during the reaction, thus imparting the multifunctionality to RfGH5_4.”

Further, the researchers pointed out that while agricultural residual biomasses are wasted or burned, causing environmental hazards (including global warming and climate change), their deconstruction by RfGH5_4 might extend its usage in food medicine too.

In July, a research team from the Indian Institute of Science, Bengaluru, found a way to extract green hydrogen from biomass, a renewable energy source.

In the same month, the Ministry of Power said that biomass co-firing in 35 thermal power plants across India has reduced CO2 emissions by 100,000 tons. Fourteen of these plants belonged to NTPC, and 21 to states and the private sector.