Can’t hide from the oncoming leather revolution

Synthetic biology is revolutionising leather. For India, where the leather industry and livestock rearing employ millions, the implications could be significant

Hideous as it may be, the journey from hide to leather is needed to stabilise the layered living composite material of hide as leather.
Hideous as it may be, the journey from hide to leather is needed to stabilise the layered living composite material of hide as leather.
By S Ramadorai, Raman Srinivasan, & S Shivaramakrishna

India is home to the largest bovine population—over 300 million, including 110 million water buffaloes. This large herd is not just the source of livelihood but also signifies wealth and well-being for our 100 million marginal dairy farmers. We are also the world’s largest exporter of beef. Furthermore, our large herd makes India a leader in the global leather industry.

But as with meat and milk, consumer preferences and industry trends are changing rapidly. Influential fashion brands have woken up to ethical alternatives to leather and fur. Other factors also compel change. Last November, Denmark culled 17 million mink due to Covid-19. Soon thereafter, Kopenhagen Fur, the leading trading hub for mink and other furs, said it will close by 2023. More recently, Israel has become the first nation to ban the sale of fur. “Using skin and fur…is immoral… and inflicts indescribable cruelty and suffering,” said the Israeli environmental protection minister Gila Gamliel in a statement.

World’s tannery
However, we take pride as the world’s tannery, producing 3 billion square feet of leather annually, enough to make three pairs of footwear for every Indian. Indeed, we are the second largest producer of leather footwear and garments. The leather industry employs over 4.5 million people in dozens of industrial clusters across the country. Animal rights activists, public health experts, and ecologists have frequently pointed out the adverse environmental and public health impact of tanneries. In a typical process, a series of chemicals successively alters the original composition of the hide. For example, alkalis help break down and remove non-fibrous proteins in the skin. Thereafter, the hide is “pickled” in sulphuric acid and other chemicals. Later still, chromium sulphate is used to tan the hide, followed by a second tanning with vegetable or synthetic tannins to soften the leather. Each stage results in effluents being released into the environment. In some clusters, the damage done by such activities is visible in satellite imagery. Hideous as it may be, the journey from hide to leather is needed to stabilise the layered living composite material of hide as leather.

Skin in the game
Mammalian hides, like milk, are a marvel of nature. Skin is obviously the largest organ in any mammal. Multi-functional by nature, it protects, senses and regulates. How has biology engineered this touch interface? Foundational scientific work for understanding leather was done in Chennai in the early 1950s. GN Ramadchandran, then a young professor of physics at Madras University, decoded the structure of collagen, jumping ahead of celebrity scientists like Watson and Crick at Cambridge, and Pauling et al at Caltech. Through diligent experiments on specially procured tail tendon of an Australian kangaroo and insightful mathematical modelling, Ramachandran showed that the structure of collagen was a triple helix and coiled. Not just this, he created a brilliant theoretical framework, the Ramachandran Plot, for protein structures that is used worldwide today.

Collagen, the main structural protein found in skin and connective tissues, is the most abundant (25-35%) protein in mammals. Long interwoven collagen fibres, aligned locally to the shape of the body of the mammal, form the structural basis of skin. For instance, when wounded, the hide’s unique biomechanical properties help accelerate wound closure and healing. Surgeons, especially plastic surgeons, are trained to take advantage of the unique properties of mammalian skin. Some 2,500 years ago, both Charakka and Sushruta described the structure of skin as a multi-layered composite with remarkable insights into the functional properties of various layers. More so than patients of elective cosmetic surgery, serious burn victims have inspired attempts to grow human skin in the lab.

Do druids dream of synbio sheep?
Pioneers of regenerative medicine are developing various methods and techniques to repair and replace tissues and even organs. Nevertheless, technologies such 3D printing of biological tissue are still far from mainstream. Making such revolutionary technologies affordable and sustainable is a challenge, requiring an interdisciplinary approach.

Professor Gabor Forgacs is the classic intellectual migrant. Trained as a theoretical physicist in Hungary, he evolved into a biological physicist and later became a synthetic biology entrepreneur. While part of the biological physics group at the University of Missouri, he founded Organovo in 2007 with his son, Andras Forgacs. Organovo aimed to 3D print biological tissue and organs. Four years later, the Forgacs father-and-son team founded another company, Modern Meadows, to grow leather using synthetic biology techniques.

Whither leather?
Broadly following synthetic biology methods similar to making heme for meat, or caseins for milk, entrepreneurs are now brewing collagen proteins. Once again, a familiar five-step process is followed. First, scientists in the Forgacs team sequenced or “read” the genomes of dozens of mammals. Then, the specific genetic code for the production of collagen is identified. Then, the genetic instructions for collagen production are inserted in industrially-harnessed microbes. Step four is a precision fermentation process, not unlike brewing beer. The microbes with collagen-producing code are grown under controlled conditions to produce collagen in scalable quantities. The fifth step results in synbio leather.

Synbio leather production technology has proved to be quite attractive. In fact, some companies are successfully experimenting with more complex organisms like filamentous fungi as possible industrial-model organisms. A well-funded startup, Bolt Threads, boldly set out to spin spider silk into profits but then struggled to untangle the problems of economically scaling up. They did produce spider silk proteins using engineered microbes, and then even spun and wove it into small quantities of ties and other fashion accessories. However, the initial promise of being able to ferment and spin silk fibre with superior engineering properties and attractive economics proved elusive. The yeast did not rise to the occasion, but there was room for mushrooms. They bolted their fortunes to synbio leather.

Scientists at the start-up began exploring filamentous fungi to produce mycelial leather, branded as Mylo. Early next year, the yoga apparel brand Lululemon is likely to launch yoga mats and bags made with mushroom-derived leather. Stella McCartney also launched garments made with mycelial leather. And other leading brands, like Adidas, are replacing animal leather in their shoes with leather made through synthetic biology. With our large leather industry, we may wish to understand the coming disruption.

Ramadorai is former vice-chairman, TCS, Srinivasan is head, TCS Ignite, and Shivaramakrishna is researcher, TCS

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