Genetically Modified Yeast Serve as New Source of Fragrances
Microbial processes already offer a wide variety of familiar scents. Wine-lovers, cheese-lovers, and soy sauce-lovers alike are already familiar with the power of microorganisms to affect our favorite smelly things. Typically, sought-after fragrances such as patchouli are extracted from plants that naturally produce appealing aromas. (For example, to acquire most essential oils, steam distillation is used to rupture the plant’s cell walls, and releasing the desired oils.) However, new biotechnology breakthroughs may create an alternative fragrance-source for the perfume industry: our single-celled buddies, yeast!
Those of you who imbibe likely already know that yeast are capable of producing alcohol and carbon dioxide in a process called fermentation. The yeast doesn’t really give a shit about either of these two byproducts; to them, all that is important is that substrate-level phosphorylation generates enough ATP for them to be alive. Thus, slight genetic modifications allow these microfungi to produce something more pleasant-smelling than alcohol. You know, stuff you might want to make perfume out of.
Companies like Amyris, a company founded on the principles of sustainable alternatives to petroleum, have dedicated departments for this sort of synthetic biology. Amyris says of their “flavors and fragrances” department, “[We will provide] an alternative, reliable, and cost-effective supply of well-known and highly sought-after ingredients which suffer from pricing, availability or sustainability concerns, [create] new ‘building blocks’ from which novel and cost-effective ingredients can be developed, and [develop] new and unique ingredients for our partners to be used directly in fragrance and flavor compounds.” In other words, plants that wildly fluctuate in cost and scarcity will no longer dictate the cost of fragrance. This could significantly reduce the cost of a bottle of perfume. There may even be beneficial effects for conservation. For example, commercial use of sandalwood (which includes a black market) may threaten the tree’s very existence in India. Alternative sources of sandalwood essential oil could help ensure the species’ survival. Furthermore, a new avenue of scent-production may open up possibilities for innovation in the perfume industry, since perfumers would no longer be shackled by mere nature. As a nice bonus, it’s a completely sustainable process.
Although only a limited number of fragrances are currently produced in this manner, scientists are working to expand the percentages of the over 6400 natural and 10000 synthetic fragrance compounds that can be generated using synthetic biology. Independent companies such as Evola, Isobionics, and Allylix are working to expand the collection of microbially-produced scents. Their current projects include smells ranging from saffron to valencene, a citrus odorant.
Critics worry that this genetically modified yeast will harm the economies of the generally-poor countries that supply us with our current delicious-smelling things. Less coherent critics worry that the product isn’t “natural” enough. For example, Friends of the Earth wrote a particularly fear-mongering piece that you can read here. An email to subscribers last August asserted, “There’s nothing ‘natural’ about genetically engineered yeast that excretes vanilla flavoring.” (I am as bleeding-heart-liberal as they come, but man do left-wing groups get weird when you start talking about GMOs!) These products admittedly do raise some labeling concerns. Can we call the product “natural”? In countries where genetically modified foods must be labeled, what do we say? Although it is chemically identical to alternatively-sourced products, it was created by means of genetic modification.
My personal concerns are more mundane. Vanillin, the phenolic aldehyde gives vanilla its principle aroma and taste, has been chemically produced from molecules like eugenol, a component of clove essential oil, or guaiacol since the 1920s. However, it doesn’t take a master chef to know that buying “vanillin” at the grocery store will give you only a faint shadow of pure vanilla extract. Vanilla extract contains hundreds of compounds on top of vanillin. Although chemically produced vanillin costs about $12 per 1 kg-1, as compared to $4000 per 1 kg-1 for vanilla that was extracted from vanilla pods, the price difference, to me, seems justified given that these two products provide such different sensory experiences. I worry that, as a relatively new industry, genetically modified yeast won’t be used to provide truly complex scent profiles for perfume. And seriously, who wants to buy a bottle of boring perfume? (That being said, I’ll be happy to be proven wrong.)