Bioproduction of a high-value synthetic ketone ester and its precursors for a UK-based value and supply chain

Lead Research Organisation: University of Nottingham
Department Name: School of Life Sciences


Biological technologies are important in the production of many types of products, and will become increasingly important in future, for several reasons:
(1) Much conventional manufacturing relies on energy and/or chemicals generated from fossil carbon resources, but there is an urgent need to transition to environmentally and economically sustainable circular economies in order to decrease greenhouse gas emissions, limit climate change and limit environmental degradation. Biological technologies can provide sustainable alternatives.
(2) Biological technologies are, or could be, superior to conventional non-biological methods of producing some types of products, because they provide important advantages in the efficiency, costs, and control over some types of chemical reactions.
(3) Biologically active chemicals are important in medicine, nutrition and agriculture, all of which are actively growing and developing areas in which many new products can be expected. Biological technologies often have advantages in production of these types of chemicals.
(4) The transition to sustainable circular economies and development of the above types of products represent huge economic opportunities for advanced, high-tech economies like the UK, the US and EU to develop, exploit and export the technologies that will be required.

This project is focused on a new product called ketone ester and two key chemical precursors used in its production, called (R)-3-hydroxybutyrate (R3HB) and (R)-1,3-butanediol (R13BD). Ketone ester is a 'nutraceutical'. Nutraceuticals are a class of products consumed as nutritional supplements, but which provide additional benefits beyond regular food or nutrients, of the kind more commonly associated with pharmaceuticals, hence the term nutraceutical.

Development and commercialisation of ketone ester is the focus of University of Oxford spin-out company TdeltaS. TdeltaS has performed many studies showing that ketone ester is safe to consume as a drink, and once inside the body is quickly broken down into natural 'ketone bodies' with beneficial effects. Ketone bodies are exceptional sources of energy, and are especially good at providing energy to the brain and blood. Ketone bodies are naturally found in the human body, but are only usually made during starvation or during special diets which can cause health problems. Consumption of ketone ester provides a rapid, safe and convenient way to obtain the benefits of ketone bodies, and studies have found benefits in enhancing athletic performance, in defence, and the potential to treat various diseases. Crucially, ketone ester has regulatory approval and has already reached a high-value market as a consumer nutraceutical in the US. Great demand for ketone ester, particularly from athletes, has rapidly outstripped supply.

Developing a reliable UK supply of R3HB and R13BD as chemical precursors for ketone ester would improve the scale of production and commercial success of ketone ester, allowing the market to grow to reflect the great demand. R3HB and R13BD also have many other uses as chemicals in other industries, with established markets. The chemical structures of R3HB and R13BD mean they can be very effectively produced by biotechnological means.

This project's industrial partner, CHAIN Biotechnology, has previously generated engineered microbial strains which produce R3HB and R13BD, but only in mixtures with other products, which does not suit the current aim.

The overall aim of this project is to apply the combined expertise, experience and capacity of the academic applicants and industrial partner CHAIN Biotechnology to develop new strains of microorganisms which produce R3HB and/or R13BD well enough that they could be used to manufacture these chemicals. The project will also demonstrate production of the ketone ester itself in engineered cells, which could lead to a simpler biomanufacturing process for ketone ester in future.

Technical Summary

(R)-3-hydroxybutyl (R)-3-hydroxybutyrate (ketone ester) is a novel nutraceutical, ingestion of which has been shown to be safe, effective and convenient way to achieve ketosis, the special metabolic state in which ketone bodies provide energy, with diverse advantages in physical and cognitive performance, and applications in sports, defence, and disease treatment. Ketone ester has FDA approval, and has reached a high-value market as a consumer nutraceutical in the US, where great demand particularly from athletes has rapidly outstripped supply.

Developing a reliable UK supply of R3HB and R13BD as chemical precursors for ketone ester would improve the scale of production and commercial success of ketone ester, allowing the market to grow. R3HB and R13BD also have many other uses as chemicals in other industries, with established markets. R3HB and R13BD are chiral, so biotechnological production is advantageous.

Anaerobic fermentation is a metabolic mode that can provide very high yields of products of interest. Clostridium bacteria are "masters of fermentation" (Todar) but genetic and metabolic modification of these organisms is challenging. The applicant is an expert in synthetic biology and metabolic engineering of Clostridium. The industrial partner CHAIN Biotechnology has generated engineered Clostridium strains which produce R3HB and R13BD, but in mixtures with other fermentation products which the strains produce naturally. To serve as the whole cell biocatalysts in commercially-viable fermentation processes for production of R3HB and R13BD, strains must be developed which produce these desired compounds as their main fermentation products. The overall aim of this project is to develop such strains by applying synthetic biology-driven metabolic engineering. Biosynthesis of the ketone ester itself by engineered cells will also be demonstrated for the first time, as proof of concept for future consolidated biomanufacture.

Planned Impact

This research will have a range of beneficiaries and different types of benefits.

The development of microbial strains which produce (R)-3-hydroxybutyrate and/or (R)-1,3-butanediol efficiently will increase the feasibility of manufacturing of these chemicals commercially using microbial fermentation. This would directly benefit the University of Nottingham and industrial partner CHAIN Biotechnology, a UK company, which aims to manufacture these chemicals and supply them to established markets. The ideal first customer will be the UK company TdeltaS, which would use these chemicals to manufacture its ketone ester nutraceutical product. Increased economic activity associated with this value and supply chain would involve jobs in the UK, and other associated contributions to the UK economy and UK wealth. The US distributor of ketone ester, HVMN, would also benefit. End users (consumers) of ketone ester would benefit from improved supply and probably decreased cost over time. Athletes are the main consumers of ketone ester at present, but over time other applications are expected, including in defence as special foods for soldiers, from which the wider public indirectly benefits; and in treatments for certain diseases.

The new synthetic biology approaches applied in this research will improve metabolic engineering of Clostridium and other microorganisms, allowing progress not possible using previous techniques, thereby improving technology for sustainable manufacturing of chemicals. This will benefit the researchers at the university and CHAIN directly involved in the project, those in the immediate academic and industrial communities who learn from the research, and ultimately a range of academic and industrial researchers in the fields of industrial biotechnology, synthetic biology, metabolic engineering, biocatalysis and microbiology. These benefits contribute to the UK skill base in the important areas of synthetic biology, metabolic engineering and industrial biotechnology.

The approaches developed in the research programme could directly or indirectly benefit the existing manufacturing processes of other companies, including others based in the UK or active in the UK, and could be important in the development of new manufacturing processes, which might involve other organisms, feedstocks and products. These benefits could in turn lead to UK jobs and other contributions to the UK economy and UK wealth.

Sustainable manufacturing is not only of economic benefit, but is also an important part of the necessary transition to sustainability and away from finite fossil carbon. This is crucial for the long-term energy security, food security, well-being and economic prosperity of the UK and nations worldwide. Therefore, the national and international public is a key ultimate beneficiary of improved biological production technology, because these issues affect everyone.

The research is at the cutting-edge of synthetic biology and metabolic engineering, and will influence the advanced education of students at the university, and in time academia more widely.


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