Dr. Leang and team have developed a pioneering carbon-negative fermentation technique to produce industrial chemicals, specifically acetone and isopropanol, using waste gases like industrial emissions and syngas. Through extensive metabolic engineering and optimization strategies, the team was able to achieve production rates of up to 3 g/L/h and selectivity of ~90%. The approach not only sidesteps the use of sugars (a common but economically challenging feedstock) but also has the added benefit of utilizing greenhouse gases, thus mitigating their environmental impact.

Key Points:

Waste Gases as Feedstock: While sugar fermentation has its limitations due to scale and economic challenges, utilizing waste gases allows decoupling from commodity prices. This innovative process converts waste into ethanol using the acetogen C. autoethanogenum, setting the stage for production of other chemicals.

Enhanced Productivity: The team achieved impressive production rates and selectivity for acetone and IPA using engineered strains of the acetogen. This proves that acetogens can be optimized for high-efficiency chemical production.

Optimization Strategy:

Pathway Design: The team delved into a vast genomic library to find the best biosynthetic genes, resulting in significantly enhanced production.

Strain Engineering: Advanced engineering techniques, including multiple genome modifications, enabled the creation of a highly productive strain.

Pathway Bottleneck Analysis: A blend of omics measurements, kinetic modeling, and systems biology led to insights into pathway bottlenecks and their subsequent mitigation.

Scale-Up Success: Successful scale-up was achieved using a 120-L field pilot, underlining the commercial viability of the approach. Despite the challenges inherent to gas fermentation scale-up, the process showed robustness and adaptability.

Environmental Benefits: This fermentation technique has a twofold environmental benefit. Not only does it produce chemicals without relying on fossil fuels, but it also captures and uses greenhouse gases, thus reducing their atmospheric release. Life Cycle Analysis confirmed that this process results in a negative carbon footprint for the produced chemicals.

Towards a Circular Economy: By transforming waste gases into valuable industrial chemicals, this process exemplifies the principles of a circular economy. Rather than extracting fresh fossil resources, it promotes the recycling of carbon from various waste streams, paving the way for a sustainable and environmentally friendly chemical industry.

Implications:

The success of this research signifies a significant stride towards sustainable chemical production. The ability to transform greenhouse gases into valuable commodities not only addresses environmental concerns but also offers promising economic prospects. By bridging innovation in biotechnology with environmental responsibility, such processes can revolutionize the future of the chemical industry.

https://doi.org/10.1038/s41587-021-01195-w