Finding a new biological process to valorise waste materials

Introduction

Celtic Renewables takes by-products of the Scottish whisky industry – draff and pot ale - and uses bacteria to turn them into high grade animal feed and also solvents such as acetone, butanol and ethanol. These bacteria, called solventogenic clostridia, have been adapted to work on whisky residues, but rejected potatoes are another available carbohydrate stream which the CRL process uses.

Production of these solvents on an industrial scale is known as the ABE (Acetone, Butanol, Ethanol) industry, and it relies on sustainable feedstocks and multiple robust strains capable of high productivity and feedstock utilisation.

Challenge

Celtic Renewables wanted to isolate and characterise solvent-producing clostridia from rejected potatos and the associated soil. It was hoped that isolates would be specifically adapted to using potatoes as a feedstock.

If productive strains could be found, these could have a beneficial economic impact on the commercial viability of ABE processes using potatoes as a feedstock.

Solution

The project team at Edinburgh Napier University isolated twenty six Clostridium-like isolates (Gram positive rod shaped bacteria) from potatoes and associated soil. Of these, seven were tested and found to be Clostridium sp.

Interrogation of the data using specialised tools and software, known collectively as Bioinformatics, determined a greater than 99% similarity to a well-known industrial strain and fermentation proved that two of these strains could produce solvents at a similar level to the control strain.

Outcome

The bacteria found were able to produce solvents at a level similar to those already in CRL’s collection.

Obtaining these new isolates will allow Celtic Renewables to expand their culture collection, making their process more robust and giving the company the opportunity to generate additional IP.

“This project has allowed CRL to undertake important work and has allowed us to expand our culture collection, which is important for providing the company with a competitive edge and ability to generate IP.”

— Celtic Renewables