Scientists talk sustainability at inaugural synthetic biology symposium

Killer tomatoes, plant-based cement, lab-grown steak and other sustainability-minded projects took center stage at the first-ever Synthetic Biology for Sustainability Symposium in early May. The discussions, held at Schwab Residential Center at Stanford University, featured experts from the Stanford School of Medicine, the School of Engineering and the Doerr School of Sustainability.

“It’s clear that synthetic biology was and is going to play an increasingly important role in how we address the challenges associated with climate change and sustainability,” said Lloyd Minor, dean of the School of Medicine. Researchers are employing synthetic biology — the engineering of organisms’ genetic material — for purposes beyond sustainability as well: Think furniture made from durable fungi or yeast that are genetically modified to create medicine.

During her opening remarks, Jennifer Widom, dean of the School of Engineering emphasized a commitment to fostering collaborations between engineers, scientists, as well as social scientists, ethicists, law scholars, and others – to ensure that we can harness the full potential of synthetic biology in a responsible manner.

Keynote speaker Jennifer Doudna, a professor at the University of California, Berkeley, who garnered a Nobel Prize in chemistry in 2020, discussed some of her new genetic engineering projects harnessing the gene-editing tool CRISPR. She emphasized that science must be pursued with a social purpose in mind and that it’s crucial for the fruits of scientists to have an impact on real people.

Researchers described five high-risk, high-reward projects stemming from new, bold — and somewhat eyebrow-raising — ideas. Some of them focused on developing tools to create new tools; some, on strategies to limit carbon emissions. Still others are devising techniques to make novel foods and useful materials from recycled plastics. Below are brief descriptions of each project:

Artificial nitrogen-fixation in plants. Ellen Yeh, MD, PhD, associate professor of pathology and of microbiology and immunology; Jenn Brophy, PhD, assistant professor of bioengineering

Plants need nitrogen, but they can’t just siphon it from the air. They can access it only when it’s “fixed” — in a form such as ammonium nitrate that they can absorb through their roots. The common solution is to use nitrogen-laden fertilizers, but excess nitrogen from fertilizers can make its way to the ocean, spurring algal growth, whose decomposition depletes the oxygen supply used by marine life, leading to dead zones. Yeh and Brophy have engineered plant organelles, a structure that lives inside a cell, that harbor a nitrogen-fixing bacteria, allowing a plant to create its own useable nitrogen and decreasing the need for fertilizers.

Mussel-inspired binders for concrete. Michael Lepech, PhD, professor of civil and environmental engineering; Possu Huang, PhD, assistant professor of bioengineering

Try to pry a mussel off a rock with your bare hands — it’s not easy. Scientists are taking inspiration from this bivalve’s natural super glue, composed of protein-laden stringy fibers, to create a more eco-friendly version of a key component of concrete, one of the world’s most common construction materials. Concrete is essentially a concoction of water, sand, gravel and something known as a binder. The binder, often composed of limestone and clay, requires a lot of resources to create, and is, sustainably speaking, problematic. Its production accounts for 4.5% of all greenhouse gases and 7% of CO2 emissions. Lepech and Huang are harnessing synthetic biology to build a sort of molecular “glue” using proteins and minerals.

Weed-killing tomatoes. Jenn Brophy, PhD, assistant professor of bioengineering; Beth Sattely, PhD, assistant professor of chemical engineering

What if we could turn the docile tomato plant we know and love into a master of self-defense? Brophy and Sattely hope to imbue the plant, the growth of which can be stunted by competing weeds, with a new power: herbicide secretion. Their goal is to create a tomato plant that secretes something called momilactone, a chemical that’s been shown to subdue weed growth. The idea is that the plant would selectively secrete the herbicide at the tips of the roots without compromising its fruit.

Converting plastic waste into components of palm oil. Matteo Cargnello, PhD, associate professor of chemical engineering; Jennifer Cochran, PhD, professor of bioengineering

Even if we recycle plastics, they pose a problem. A plastic water bottle doesn’t turn into another plastic water bottle — it degrades too much. And discarded plastic often ends up polluting the ocean. The researchers dream of something called chemical recycling, in which discarded items, such as plastic, are broken down into their component parts, which are then used to build something new. Cochran, Cargnello and their team plan to use chemicals to break down recycled plastic and convert it into palm oil. As manufacturers of palm oil raze forests to plant palm trees and plastics amass in oceans, such a process could protect the environment on both fronts.

Lab meat. Helen Blau, PhD professor of microbiology and immunology; Sarah Heilshorn, PhD, professor of materials science and engineering

Of all the meats, beef takes the biggest toll on the environment, yet global beef consumption is on the rise. That’s why Blau and Heilshorn are embarking on a new project in their lab: growing a steak from the cells of a cow. This new approach to satiating carnivores is known as lab-cultured meat, or cellular agriculture. The researchers’ aim is to sustainably create actual meat, rather than plant-based meat substitutes. Others have tried to grow beef in the lab, but it’s yielded food items that are more akin to ground beef than a slab of steak. So, how do you take a beef-ish paste and turn it into a filet? Scaffolding. The team is turning to 3D printing using biological materials to create a structure for the cultured cells to grow in a way that recapitulates genuine meat.

To close out the symposium, Stanford University president Marc Tessier-Lavigne shared his vision for how researchers across campus will usher in a new era of discovery that’s rooted in synthetic biology. He highlighted three key components: deepening human knowledge, enabling interdisciplinary teams and translating research discoveries into real-world solutions.

“There’s an expression I like to use: ‘No one can whistle a symphony. It takes a whole orchestra to play it,’” he said. “As I think about the sustainability challenges we face and the solutions they will require, this has never felt truer.”