New discovery increases efficiency and profits of bioethanol production

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

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

Improved process yield and environmental benefits

Bioethanol, an important source of renewable energy, is obtained by the fermentation of sugars by yeast, mainly Saccharomyces cerevisiae. However, contaminating bacteria present in the feedstock can significantly affect fermentation efficiency. Until now, these contaminating microbes have been characterized using methods that did not fully capture their diversity or impact.

“Our study provides a comprehensive analysis of microbial populations at all stages of the industrial bioethanol process in two large Brazilian biorefineries. By using a combination of shotgun metagenomics and cultivation-based methods, we identified ecological factors that influence community dynamics and bioconversion efficiency,” says Postdoc Felipe Lino from DTU Biosustain. “The study shows that specific bacterial strains, influenced by temperature, can hinder or improve ethanol yield. This improvement could only have been achieved with the advanced techniques we used.”

The findings could lead to a more than 5% increase in process yield, equating to approximately $1.6 billion in increased revenue and reduced carbon emissions.₂ -emissions by about 2 million tons per year, if we look at Brazil alone.

Strain-level resolution: revealing hidden bacterial dynamics

The researchers found that the interaction between different species has a significant impact on ethanol yield. When Lactobacillus amylovorus is present in higher concentrations, yields are significantly better.

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

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

Paving the way for new microbial and process control solutions

The results of this study may lead to the development of novel microbial and process control solutions that can combat unwanted microbes and unlock significant performance improvements in bioethanol production. This could lead to more cost-effective biofuels, higher efficiency and significant reductions in CO₂ -emissions, supporting global efforts to reduce greenhouse gas emissions.

The research results are particularly relevant for biofuel and industrial biotechnology companies, as well as research groups focusing on bioinformatics tools for strain-level microbiome analysis. The novel gene catalogue and functional analyses developed in this study provide valuable resources for discovering novel enzymes and metabolic traits for robust industrial strains. These insights can also be applied to other metagenomics studies, such as gut microbiome dynamics, soil and crop-associated microbiomes.