A Co-Culture Method for Biofuel and Biochemical Production from Untreated Syngas

INV-21103

Background

Syngas, a clean and renewable energy, is expected to widely replace traditional forms of energy. Also, there is a rising demand for green chemicals with a wide variety of applications, produced from syngas and derivatives. Gas fermentation using acetogenic bacteria has emerged as a promising method to synthesis gas. Acetogenic bacteria grow using gases including carbon monoxide (CO), hydrogen (H2), and carbon dioxide (CO2) and convert them to acetic acid and ethanol. It is widely anticipated that gas fermentation using acetogens will be a prominent component of the circular bioeconomy in the 21st century. Despite the promise of gas fermentation, there are two significant technological challenges in this process. First, oxygen is detrimental to acetogenic bacteria by destroying metal cofactors, and such a sensitivity necessitates costly pre-treatment of the gas stream to remove trace oxygen before fermentation. The second challenge is related to the removal of byproducts. While ethanol is the most desirable product of syngas fermentation, byproducts such as acetic acid are also produced in large quantities. These byproducts have inhibitory effects on the fermentation process, and it is hard to separate. Such challenges decrease fermentation efficiency and increase the cost of the final product, thereby preventing the commercialization of syngas fermentation process.

Technology Overview

Researchers at Northeastern developed a fermentation platform using a co-culture of aerobic and anaerobic microbes that allows conversion of syngas to high-value biofuels and biochemicals without the need for gas pre-treatment. Though the concept of co-culture has existed before, this technology is novel in terms of developing the co-culture in a single vessel. In this vessel, oxygen-consuming bacteria are co-cultured with the oxygen-intolerant microbe and reduces the levels of oxygen. Such an approach reduces the pre-treatment cost and allows access to higher-value compounds (e.g. bioethanol), thereby increasing the production yield. This technology is the first to demonstrate that an acetogenic microbe can grow in the presence of low levels of oxygen. Also, there is a potential to engineer each microbe to synergistically augment the growth of the other. Unique features of this system allow overcoming current challenges of gas fermentation; thus, significantly reducing the operating costs and dramatically expanding the product portfolio of gas fermentation.

Benefits

• Reduced pre‑treatment cost
• High fermentation yield
• Expanded product range
• Increased fermentation robustness

Applications

• Production of biofuels/biochemicals

Opportunity

• Research collaboration
• Licensing
• Commercial partner