Unicamp develops yeast to optimize corn ethanol.

Corn ethanol production is a recent phenomenon in Brazil, but this industry already accounts for about 30% of the country's ethanol production, which is one of the world's largest producers of the biofuel. To keep up with this rapid growth, researchers at the State University of Campinas (Unicamp) have developed a genetically modified yeast capable of increasing the efficiency of corn fermentation.  

The invention was developed by researchers at the Genomics and Bioenergy Laboratory of the Institute of Biology (IB) at the University, and was coordinated by Gonçalo Amarante Guimarães Pereira, a professor at the IB. The technology was protected and licensed to Unicamp's spin-off company, Bioinfood, through a strategy of the Unicamp Innovation Agency (Inova Unicamp), with the intervention of the Unicamp Development Foundation (Funcamp).  

The challenge of fermentation for corn ethanol.  

Corn ethanol emerged as a complementary alternative to sugarcane ethanol, since corn offers significant logistical advantages. Unlike sugarcane, which needs to be processed within 48 hours of harvesting, corn grain can be stored in silos for months without losing quality. This characteristic allows producers to take advantage of the soybean off-season to cultivate corn, which favors crop rotation and reduces environmental impact. Furthermore, the corn production chain generates high-value byproducts, such as oil and animal feed, making corn biorefineries even more economically attractive.  

“The cost of corn ethanol is much lower than the cost of sugarcane ethanol, and it is much less complex to produce because they don't have the agricultural aspect. After being harvested, corn can be stored, something that is not possible with sugarcane,” emphasizes Pereira.  

Despite its advantages, the corn fermentation process faces a specific technical challenge. The yeast traditionally used in ethanol production easily converts sugarcane sugar into ethanol. However, corn does not contain this same type of sugar. Its main component is starch, a long chain of glucose molecules that yeast cannot process directly.  

To solve this, it is necessary to break down the starch into smaller molecules before fermentation, in a process that uses two enzymes called amylases. The first, alpha-amylase, acts at high temperatures, generally above 90 degrees Celsius, and fragments the starch into medium-chain fibers. The second, glucoamylase, acts during fermentation and completes the breakdown, transforming these fibers into glucose molecules that the yeast can ferment.  

The problem is that traditional alpha-amylase only works at high temperatures, incompatible with the fermentation phase, which occurs around 30 degrees Celsius. Therefore, it needs to be added beforehand, in a separate step, which increases the cost of the process. Furthermore, even with this prior step, a portion of the starch, estimated at about ten percent, is not completely broken down and ends up being discarded during fermentation, reducing the final ethanol yield.  

Finding the solution with computer assistance  

The technology developed at Unicamp acts as a solution precisely to this bottleneck. Using bioinformatics tools and computational analysis of large genomic databases, the team searched for enzymes not yet used in industrial yeasts. The most challenging criterion was finding an alpha-amylase capable of functioning at low temperatures, close to that of fermentation, something rare among known enzymes, since almost all of them only function at high temperatures.  

“It was a major effort to search, through the millions of publicly available protein data sets from all sequenced organisms, for an alpha-amylase that functions at low temperatures. 99,9% of alpha-amylases only work at 80 degrees,” explains Marcelo Falsarella Carazzolle, one of the researchers responsible for the technology.  

After identifying the promising enzymes, the team inserted the corresponding genes into an industrial yeast and created a strain capable of producing both the new alpha-amylase and a new glucoamylase on its own, without depending on the external addition of these enzymes during the process. In bench tests, comparing the new yeast with a conventional strain, the researchers verified that the new strain completely eliminates the need for external glucoamylase addition and is even able to break down some of the residual starch that is normally lost in the traditional process.  

This dual capability represents a direct advantage for the industry, with the potential to increase ethanol production using the same amount of corn, in addition to reducing costs associated with purchasing commercial enzymes.  

Licensing and market potential  

All the work of identifying the enzymes was carried out in just over two years, a relatively short period made possible by the rapid reproduction rate of the microorganisms used in the experiments. Although recent, the results obtained in the research have already demonstrated sufficient potential to attract market interest.  

Currently, the invention is licensed to Unicamp's spin-off company, Bioinfood, which validates the technology on a larger scale and helps researchers access hydrolyzed starch from real industrial processes, something that was not possible to reproduce under benchtop conditions.  

According to the researchers, the goal of this new phase is to confirm on an industrial scale the gains observed in the laboratory, mainly the reduction of starch not utilized in the conventional process. If confirmed, these results could make the yeast a relevant commercial product for the entire corn ethanol production chain in Brazil.  

“This is a technology of the highest scientific level. It is our role to transform it into a relevant commercial product, with all the rigorous validation that industrial scale demands,” comments Gleidson Teixeira, co-founder, Scientific & Commercial Director at Bioinfood.