Compost the new ethanol?

fermenting compost

Enzymes from garden compost could favour bioethanol production

The researcher in question is Nadia Skorupa Parachin and the secret of her technique is enzymes that she extracted from garden soil. If ethanol can be successfully made from xylose then ethanol production could increase by over 20 per cent – to the benefit of cheaper environmentally friendly fuel.

Ethanol is manufactured by fermenting sugars from plant material. At present, xylose is not used, despite being the second most common type of sugar found in nature. Succeeding with xylose requires quick acting enzymes that can get the yeast to ferment the less appetising xylose.

Nadia tested her enzymes and the first results show that enzymes bind xylose more efficiently than those that have been tested previously.

“In order for carbohydrates in forestry, plant and waste products to be used for ethanol production, enzymes are required in the yeast that ‘eat up’ the sugar and convert it into ethanol. If we just want to make use of the glucose then normal baker’s yeast is sufficient. However, if the xylose is also to be converted to ethanol, then genetic modifications have to be made to the yeast”, explains Ms Skorupa Parachin, who has recently patented her newly discovered enzymes.

Nadia began by extracting DNA from a soil sample, then she cut it into small pieces. She was then able to build up a DNA library.

After that she identified the most appropriate genes by coupling enzyme activity to growth on xylose.

Nadia’s decision to use soil was quite simply because soil contains so many bacteria.

“One gram of soil contains ten billion bacteria! Enzymes and other proteins are found in almost unlimited numbers and can have all sorts of unexplored properties. I collected the soil samples from a garden in Höör, but any soil can be used.”

The reason why no researcher has previously identified new enzymes for xylose in this way is because it is not all that easy. Marie Gorwa-Grauslund, who is Nadia’s supervisor, was the first person to realise that this genetic technique could work in this context. The technique, known as metagenomics, was originally used in environmental studies.

“The most interesting part is really the method itself. We have reasoned along entirely new lines. In fact, it has taken several months to develop the method”, explains Professor Gorwa-Grauslund.

“There are still a number of pieces of the jigsaw that must be put in place if ethanol production from xylose is to become financially viable. The process must be speeded up. But we hope that in the long term our method can help to make bioethanol production more efficient”, says Professor Gorwa-Grauslund.

Get Social About Me