The new discovery increases the efficiency and profits of bioethanol production

A new technique to monitor pollution in bioethanol production could increase revenue by more than $1.6 billion and reduce CO2₂ emissions with 2 million tons.

For the first time ever, researchers at the Novo Nordisk Foundation Center for Biosustainability (DTU Biosustain) have investigated the population of contaminants from the sugarcane bioethanol production process at strain-level resolution. Their study reveals how strain dynamics are directly involved in process performance, highlighting the need for improved microbial control techniques to increase industrial efficiency. The results of the research appear in Nature Communications.

Improved process yield and environmental benefits

Bioethanol, a major source of renewable energy, is derived from the fermentation of sugars by yeast, primarily Saccharomyces cerevisiae. However, contaminating bacteria present in the raw material can significantly affect the fermentation efficiency. Until now, these pollutant microbes have been characterized using methods that did not fully capture their diversity or impact.

“Our research provides a comprehensive analysis of microbial populations at all stages of the bioethanol industrial process in two major Brazilian biorefineries. Using a combination of shotgun metagenomics and cultivation-based methods, we identified ecological factors that influence the dynamics of community and bioconversion efficiency.” says Postdoc Felipe Lino from DTU Biosustain. “The study shows that specific bacterial strains, affected by temperature, can inhibit or enhance ethanol production. This improvement can only be achieved with the advanced techniques we used.”

The findings could result in a more than 5% increase in process yield, translating to an estimated $1.6 billion in increased revenue and a reduction in CO₂ emissions by about 2 million tons per year, considering only Brazil.

Strain-level resolution: Unraveling hidden bacterial dynamics

The researchers found that the interaction between different species significantly affects ethanol yield. Whenever Lactobacillus amylovorus is present in higher concentrations, the yields are significantly better.

Professor Morten Sommer from DTU Biosustain explains, “We mapped microbial populations at strain-level resolution to reveal the true impact of non-yeast microbes on fermentation performance. We identified specific strains of the L. fermentum species that cause the most damage in the process, while other strains are neutral and should even be kept as a buffer against harmful ones.

“Increasing temperatures were associated with the growth of specific L. fermentum strains that negatively affect yeast viability and fermentation efficiency. This underscores the importance of adopting higher resolution methods in the future to monitor microbial communities.”

Paving the way for new microbial and process control solutions

The results of this study may lead to the development of new microbial and process control solutions that can control undesirable microbes and unlock significant performance improvements in bioethanol production. This can translate into more cost-effective biofuels, increased efficiency and a significant reduction in CO₂ emissions, supporting global efforts to reduce greenhouse gas emissions.

The research results are particularly relevant to biofuels and industrial biotechnology companies, as well as research groups focused on bioinformatics tools for analyzing microbiomes at strain-level resolution. The new gene catalog and functional assays developed in this study provide valuable resources for the discovery of new enzymes and metabolic traits for robust industrial strains. Also, these insights can be applied to other metagenomic studies, such as gut microbiome dynamics, soil and crop-related microbiomes.