Gelidium agar

Restrictions on harvests and exports of Gelidium seaweed in Morocco have affected the global supply of the lab reagent agar. Credit: Dr. Ignacio Bárbara, Seaweed

Ewen Callaway writes in the jounal Nature that restrictions on harvests and exports of Gelidium seaweed in Morocco have affected the global supply of the lab reagent agar. Microbiology’s most important reagent is in short supply, with potential consequences for research, public health and clinical labs around the world.

Agar – the seaweed-derived, gelatinous substance that biologists use to culture microbes – is experiencing a global downturn, marine biologists, agar producers and industry analysts told Nature. “There’s not enough seaweed for everyone, so basically we are now reducing our production,” said Pedro Sanchez, deputy managing director of Industrias Roko in Polígono de Silvota, Spain, which processes seaweed to make about 40% of the world’s agar.

The shortage can be traced to newly enforced trade restrictions on the seaweed, arising from environmental concerns that the algae are being overharvested. It is unclear how deeply the dearth will hit researchers, but it has already pushed wholesale prices of agar to an all-time high of around US$35 – $45 per kilogram – nearly triple the price before scarcities began. Individual researchers, who buy packaged agar from lab-supply companies, can pay many times this amount.

One major supplier, Thermo Fisher Scientific of Waltham, Massachusetts, said that it has stopped selling two ‘raw’ agar products – agar that has not been mixed with other ingredients – until 2016, so that it can prioritize more-popular products that contain a mixture of agar and growth nutrients. The company reports that about 200 of its customers have been affected. Another major lab-supply company, Millipore Sigma in Billerica, Massachusetts, has also halted sales of raw agar, and it says that it will re-evaluate its supplies early next year.

Millipore Sigma blames the shortage on competition from food companies for purified agar. The global demand from food-makers, at several thousand tons annually, dwarfs the 900 tons that go to lab-supply companies.

Since the introduction of agar plates in the 1880s – which enabled researchers to isolate tuberculosis, cholera and other disease-causing bacteria for the first time – bacteriological agar has been derived from red seaweed species belonging to the genus Gelidium.

The geographical sources of Gelidium have shifted over the decades. Before the Second World War, Japan was king; Portugal was also once a leading supplier. Now, most of the world’s agar derives from Gelidium grown in Morocco, with Spain in second place and Portugal, France, Mexico, Chile, South Africa, Japan and South Korea all contributing smaller quantities.