New low-cost method to synthesise grapefruit substance

An expensive natural compound found in minute quantities in grapefruits can be synthesised cheaply and in useful quantities from sugar, scientists say.
The substance, Nootkatone, is expensive and costs more than 2,86,000 rupees per kg but now it can be produced biotechnologically from sugar at just 71 rupees per kg, researchers said.
Nootkatone gives grapefruit its flavour and aroma and is used as a high quality, natural flavouring ingredient in millions of litres of soft and lifestyle drinks, as a biopharmaceutical component or as a natural insect repellent.
"We have installed new genetic information in the yeast Pichia pastoris, so that our cells are able to produce Nootkatone from sugar," said researcher Tamara Wriessnegger from The Austrian Centre of Industrial Biotechnology (ACIB).

The genome of the yeast cells has been extended with four foreign genes derived from the cress Arabidopsis thaliana, the Egyptian henbane Hyoscyamus muticus, the Nootka cypress Xanthocyparis nootkatensis and from baker's yeast Saccharomyces cerevisiae.
Ultimately, the aroma found in one grapefruit leads to millions of litres of tasty juice, researchers said.

With the help of the new genes the yeast is capable to synthesise the high-prized, natural flavour in a cheap way and in useful quantities from sugar.
Nootkatone is an important substance for the food, pharmaceutical and chemical industries, said Harald Pichler.
As an insecticide it is effective against ticks, mosquitoes or bedbugs. In the medical field, the substance has shown activity against cancer cell lines. In cosmetics, people appreciate the good smell, in soft drinks a fine, subtle taste.

"With our method, the important and expensive terpenoid Nootkatone can be produced industrially in an environmentally friendly, economical and resource-saving way in useful quantities," said Pichler.