US scientists said they had used baker's yeast to make a key ingredient of malaria drugs, a feat that could iron out fluctuations in supply caused by sourcing the chemical from a Chinese herb.
One of the revolutions in malaria treatment in recent decades has been the advent of artemisinin drugs, whose active ingredient comes from a traditional Chinese herb, Artemisia annua.
But weather can affect harvests of the plant, causing shortages and price spikes.
How the anti-drug were manufactured
In a study published in Nature, a team led by Chris Paddon of Amyris Inc., a biotech firm based in Emeryville, California, reported on a way to ferment artemisinic acid - a precursor to artemisinin - from genetically-engineered baker's yeast.
Their technique derives 25 grammes of concentrate from a litre of artemisinic acid. A previous attempt, reported by a European team last year, made only 1.6 grammes per litre.
The artemisinic acid can then be converted to artemisin by a simple chemical process using oxygen as a catalyst.
"Because all intellectual property rights have been provided free of charge, this technology has the potential to increase provision of first-line antimalarial treatments to the developing world at a reduced average annual price," the researchers said.
In 2010 there were more than 200 million cases of malaria, and at least 655 000 deaths, according to the UN's World Health Organisation.