Genetically engineered microorganisms could replace flowers as sources of ingredients for perfumes - and even recreate scents from plants long extinct
SITTING before me is a vial of cloudy white broth. Biologist Patrick Boyle invites me to take a sniff. To my amateur nose, the liquid smells green and sweet, a little like fresh-cut grass, a little like a bunch of flowers.
The concoction is a microbial perfume. Cooked up in the laboratories of Ginkgo BioWorks in Boston, it contains yeast that has been genetically engineered to smell of roses. Its ultimate purpose: to become part of a designer fragrance, one where its presence rivals the rose oils often used in luxury scents.
The "cultured rose" was born out of a marriage between Ginkgo – which bills itself as "the world's first organism engineering foundry" – and Robertet, a French flavours and fragrance company founded in 1850. Robertet prides itself on the natural ingredients it uses in perfumes created for clients such as Chloé and Bottega Veneta, as well as its scents for household products like detergents.
Rose oil is a classic perfume component. Traditionally, roses are grown in vast fields in Bulgaria or Turkey, then picked by hand and distilled to extract the aromatic oil. But from the fragrance companies' perspective, this approach is unreliable. Both the quality and the price of roses can fluctuate wildly from year to year, influenced by factors such as natural disasters, labour shortages, diseases or simply a poor growing season. "You have raw materials that will go from $10 to $100 a kilo because there's a shortage or an embargo," says Bob Weinstein, chief operating officer at Robertet.
Perfumers can use a synthetic substitute, created by mixing four or five chemicals together to approximate natural rose scent. This can be convincing, but some perfumers say it falls short of the rich subtleties that would distinguish a high-end fragrance.
Culturing microbes to produce scents is not only cheaper than using naturally sourced ingredients, but also gives perfumers more control over fragrances, says Ben Fundaro, director of perfumery at Robertet. "We're basically at the mercy of nature with some of these crops," he says. "If we could produce in a more controlled environment, the odour would be more consistent."
The approach being pursued at Ginkgo starts with the DNA of the rose itself. In order to make the compounds responsible for their flowers' distinctive smell (see "On the scent of a rose"), plants need to use enzymes, and the team must find the genes coding for these. Once that's done, Ginkgo can engineer a number of strains of yeast, each with a genome modified to ensure that the microbes' metabolic reactions result in one of the desired compounds. This might be accomplished by tweaking the genome or by adding genes from a rose or another plant, such as corn or hyacinth, that does the same job.
"Our goal is to recreate the rose biosynthetic pathways, even if we don't use rose genes to do it," says Boyle. "We often find that a different but highly related gene from a different species works better in yeast than the rose gene that has the function we want."
Every month or so, Ginkgo sends samples of the strains to Robertet perfumers. They evaluate them and send critiques back to Ginkgo, asking for a scent to be made stronger or weaker, or to play up its floral, musky or fruity qualities. Once the strains for the individual components have been cleared by the perfumers, Ginkgo will produce a single strain of yeast that has all the genetic modifications – their attempt at the ideal rose scent.
The best rose oil, says Fundaro, smells fresh and clean, "very true to the way the rose would smell in the air if you were in a rose garden or next to a bouquet". One issue with the cultured rose fragrance is that it retains the yeast's characteristic sour smell. Before Boyle's team is done, they must find a way to downplay this odour, perhaps by moderating some of the genetic pathways that contribute to it, or by carefully filtering the final product.
Ginkgo isn't the only company to have anticipated manufacturers' desire for cultured fragrances and flavours. Californian company Amyris has partnered with Swiss firm Firmenich to work on lab-made patchouli oil. Allylix, another California company, cultures a version of vetiver oil, a woody extract of an Indian perennial grass.
"The basic material is sugar and microorganisms, so it's much more stable," says Toine Janssen, CEO of Isobionics, based in Geleen in the Netherlands. Isobonics relies on bacteria to make valencene, a compound found in oranges and often used in soft drinks. "It's like brewing beer. If you have lots of fermenters, you can make as much as you like."
Shota Atsumi, a chemist at the University of California, Davis, sees another potential upside to cultured products: they may replace some synthetic scents, the vast majority of which are produced from petrochemicals. Last year, in an effort to demonstrate the potential of cultured scents as a renewable alternative, Atsumi's research team altered the DNA of E. coli to make the bacteria smell like bananas and blueberries.
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