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    Pivot Bio is using microbial nitrogen to make agriculture more sustainable

    The Haber-Bosch process, which converts atmospheric nitrogen to make ammonia fertilizer, revolutionized agriculture and helped feed the world’s growing population, but it also created huge environmental problems. It is one of the most energy-intensive chemical processes in the world, responsible for 1-2 percent of global energy consumption. It also releases nitrous oxide, a potent greenhouse gas that harms the ozone layer. Excess nitrogen also routinely runs off farms into waterways, harming marine life and polluting groundwater.In place of synthetic fertilizer, Pivot Bio has engineered nitrogen-producing microbes to make farming more sustainable. The company, which was co-founded by Professor Chris Voigt, Karsten Temme, and Alvin Tamsir, has engineered its microbes to grow on plant roots, where they feed on the root’s sugars and precisely deliver nitrogen in return.Pivot’s microbial colonies grow with the plant and produce more nitrogen at exactly the time the plant needs it, minimizing nitrogen runoff.“The way we have delivered nutrients to support plant growth historically is fertilizer, but that’s an inefficient way to get all the nutrients you need,” says Temme, Pivot’s chief innovation officer. “We have the ability now to help farmers be more efficient and productive with microbes.”Farmers can replace up to 40 pounds per acre of traditional nitrogen with Pivot’s product, which amounts to about a quarter of the total nitrogen needed for a crop like corn.Pivot’s products are already being used to grow corn, wheat, barley, oats, and other grains across millions of acres of American farmland, eliminating hundreds of thousands of tons of CO2 equivalent in the process. The company’s impact is even more striking given its unlikely origins, which trace back to one of the most challenging times of Voigt’s career.A Pivot from despairThe beginning of every faculty member’s career can be a sink-or-swim moment, and by Voigt’s own account, he was drowning. As a freshly minted assistant professor at the University of California at San Francisco, Voigt was struggling to stand up his lab, attract funding, and get experiments started.Around 2008, Voigt joined a research group out of the University of California at Berkeley that was writing a grant proposal focused on photovoltaic materials. His initial role was minor, but a senior researcher pulled out of the group a week before the proposal had to be submitted, so Voigt stepped up.“I said ‘I’ll finish this section in a week,’” Voigt recalls. “It was my big chance.”For the proposal, Voigt detailed an ambitious plan to rearrange the genetics of biologic photosynthetic systems to make them more efficient. He barely submitted it in time.A few months went by, then the proposal reviews finally came back. Voigt hurried to the meeting with some of the most senior researchers at UC Berkeley to discuss the responses.“My part of the proposal got completely slammed,” Voigt says. “There were something like 15 reviews on it — they were longer than the actual grant — and it’s just one after another tearing into my proposal. All the most famous people are in this meeting, future energy secretaries, future leaders of the university, and it was totally embarrassing. After that meeting, I was considering leaving academia.”A few discouraging months later, Voigt got a call from Paul Ludden, the dean of the School of Science at UC Berkeley. He wanted to talk.“As I walk into Paul’s office, he’s reading my proposal,” Voigt recalls. “He sits me down and says, ‘Everybody’s telling me how terrible this is.’ I’m thinking, ‘Oh my God.’ But then he says, ‘I think there’s something here. Your idea is good, you just picked the wrong system.’”Ludden went on to explain to Voigt that he should apply his gene-swapping idea to nitrogen fixation. He even offered to send Voigt a postdoc from his lab, Dehua Zhao, to help. Voigt paired Zhao with Temme, and sure enough, the resulting 2011 paper of their work was well-received by the nitrogen fixation community.“Nitrogen fixation has been a holy grail for scientists, agronomists, and farmers for almost a century, ever since somebody discovered the first microbe that can fix nitrogen for legumes like soybeans,” Temme says. “Everybody always said that someday we’ll be able to do this for the cereal crops. The excitement with Pivot was this is the first time that technology became accessible.”Voigt had moved to MIT in 2010. When the paper came out, he founded Pivot Bio with Temme and another Berkeley researcher, Alvin Tamsir. Since then, Voigt, who is the Daniel I.C. Wang Professor at MIT and the head of the Department of Biological Engineering, has continued collaborating with Pivot on things like increasing nitrogen production, making strains more stable, and making them inducible to different signals from the plant. Pivot has licensed technology from MIT, and the research has also received support from MIT’s Abdul Latif Jameel Water and Food Systems Lab (J-WAFS).Pivot’s first goals were to gain regulatory approval and prove themselves in the marketplace. To gain approval in the U.S., Pivot’s team focused on using DNA from within the same organism rather than bringing in totally new DNA, which simplified the approval process. It also partnered with independent corn seed dealers to get its product to farms. Early deployments occurred in 2019.Farmers apply Pivot’s product at planting, either as a liquid that gets sprayed on the soil or as a dry powder that is rehydrated and applied to the seeds as a coating. The microbes live on the surface of the growing root system, eating plant sugars and releasing nitrogen throughout the plant’s life cycle.“Today, our microbes colonize just a fraction of the total sugars provided by the plant,” Temme explains. “They’re also sharing ammonia with the plant, and all of those things are just a portion of what’s possible technically. Our team is always trying to figure out how to make those microbes more efficient at getting the energy they need to grow or at fixing nitrogen and sharing it with the crop.”In 2023, Pivot started the N-Ovator program to connect companies with growers who practice sustainable farming using Pivot’s microbial nitrogen. Through the program, companies buy nitrogen credits and farmers can get paid by verifying their practices. The program was named one of the Inventions of the Year by Time Magazine last year and has paid out millions of dollars to farmers to date.Microbial nitrogen and beyondPivot is currently selling to farmers across the U.S. and working with smallholder farmers in Kenya. It’s also hoping to gain approval for its microbial solution in Brazil and Canada, which it hopes will be its next markets.”How do we get the economics to make sense for everybody — the farmers, our partners, and the company?” Temme says of Pivot’s mission. “Because this truly can be a deflationary technology that upends the very expensive traditional way of making fertilizer.”Pivot’s team is also extending the product to cotton, and Temme says microbes can be a nitrogen source for any type of plant on the planet. Further down the line, the company believes it can help farmers with other nutrients essential to help their crops grow.“Now that we’ve established our technology, how can Pivot help farmers overcome all the other limitations they face with crop nutrients to maximize yields?” Temme asks. “That really starts to change the way a farmer thinks about managing the entire acre from a price, productivity, and sustainability perspective.” More

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    Streamlining data collection for improved salmon population management

    Sara Beery came to MIT as an assistant professor in MIT’s Department of Electrical Engineering and Computer Science (EECS) eager to focus on ecological challenges. She has fashioned her research career around the opportunity to apply her expertise in computer vision, machine learning, and data science to tackle real-world issues in conservation and sustainability. Beery was drawn to the Institute’s commitment to “computing for the planet,” and set out to bring her methods to global-scale environmental and biodiversity monitoring.In the Pacific Northwest, salmon have a disproportionate impact on the health of their ecosystems, and their complex reproductive needs have attracted Beery’s attention. Each year, millions of salmon embark on a migration to spawn. Their journey begins in freshwater stream beds where the eggs hatch. Young salmon fry (newly hatched salmon) make their way to the ocean, where they spend several years maturing to adulthood. As adults, the salmon return to the streams where they were born in order to spawn, ensuring the continuation of their species by depositing their eggs in the gravel of the stream beds. Both male and female salmon die shortly after supplying the river habitat with the next generation of salmon. Throughout their migration, salmon support a wide range of organisms in the ecosystems they pass through. For example, salmon bring nutrients like carbon and nitrogen from the ocean upriver, enhancing their availability to those ecosystems. In addition, salmon are key to many predator-prey relationships: They serve as a food source for various predators, such as bears, wolves, and birds, while helping to control other populations, like insects, through predation. After they die from spawning, the decomposing salmon carcasses also replenish valuable nutrients to the surrounding ecosystem. The migration of salmon not only sustains their own species but plays a critical role in the overall health of the rivers and oceans they inhabit. At the same time, salmon populations play an important role both economically and culturally in the region. Commercial and recreational salmon fisheries contribute significantly to the local economy. And for many Indigenous peoples in the Pacific northwest, salmon hold notable cultural value, as they have been central to their diets, traditions, and ceremonies. Monitoring salmon migrationIncreased human activity, including overfishing and hydropower development, together with habitat loss and climate change, have had a significant impact on salmon populations in the region. As a result, effective monitoring and management of salmon fisheries is important to ensure balance among competing ecological, cultural, and human interests. Accurately counting salmon during their seasonal migration to their natal river to spawn is essential in order to track threatened populations, assess the success of recovery strategies, guide fishing season regulations, and support the management of both commercial and recreational fisheries. Precise population data help decision-makers employ the best strategies to safeguard the health of the ecosystem while accommodating human needs. Monitoring salmon migration is a labor-intensive and inefficient undertaking.Beery is currently leading a research project that aims to streamline salmon monitoring using cutting-edge computer vision methods. This project fits within Beery’s broader research interest, which focuses on the interdisciplinary space between artificial intelligence, the natural world, and sustainability. Its relevance to fisheries management made it a good fit for funding from MIT’s Abdul Latif Jameel Water and Food Systems Lab (J-WAFS). Beery’s 2023 J-WAFS seed grant was the first research funding she was awarded since joining the MIT faculty.  Historically, monitoring efforts relied on humans to manually count salmon from riverbanks using eyesight. In the past few decades, underwater sonar systems have been implemented to aid in counting the salmon. These sonar systems are essentially underwater video cameras, but they differ in that they use acoustics instead of light sensors to capture the presence of a fish. Use of this method requires people to set up a tent alongside the river to count salmon based on the output of a sonar camera that is hooked up to a laptop. While this system is an improvement to the original method of monitoring salmon by eyesight, it still relies significantly on human effort and is an arduous and time-consuming process. Automating salmon monitoring is necessary for better management of salmon fisheries. “We need these technological tools,” says Beery. “We can’t keep up with the demand of monitoring and understanding and studying these really complex ecosystems that we work in without some form of automation.”In order to automate counting of migrating salmon populations in the Pacific Northwest, the project team, including Justin Kay, a PhD student in EECS, has been collecting data in the form of videos from sonar cameras at different rivers. The team annotates a subset of the data to train the computer vision system to autonomously detect and count the fish as they migrate. Kay describes the process of how the model counts each migrating fish: “The computer vision algorithm is designed to locate a fish in the frame, draw a box around it, and then track it over time. If a fish is detected on one side of the screen and leaves on the other side of the screen, then we count it as moving upstream.” On rivers where the team has created training data for the system, it has produced strong results, with only 3 to 5 percent counting error. This is well below the target that the team and partnering stakeholders set of no more than a 10 percent counting error. Testing and deployment: Balancing human effort and use of automationThe researchers’ technology is being deployed to monitor the migration of salmon on the newly restored Klamath River. Four dams on the river were recently demolished, making it the largest dam removal project in U.S. history. The dams came down after a more than 20-year-long campaign to remove them, which was led by Klamath tribes, in collaboration with scientists, environmental organizations, and commercial fishermen. After the removal of the dams, 240 miles of the river now flow freely and nearly 800 square miles of habitat are accessible to salmon. Beery notes the almost immediate regeneration of salmon populations in the Klamath River: “I think it was within eight days of the dam coming down, they started seeing salmon actually migrate upriver beyond the dam.” In a collaboration with California Trout, the team is currently processing new data to adapt and create a customized model that can then be deployed to help count the newly migrating salmon.One challenge with the system revolves around training the model to accurately count the fish in unfamiliar environments with variations such as riverbed features, water clarity, and lighting conditions. These factors can significantly alter how the fish appear on the output of a sonar camera and confuse the computer model. When deployed in new rivers where no data have been collected before, like the Klamath, the performance of the system degrades and the margin of error increases substantially to 15-20 percent. The researchers constructed an automatic adaptation algorithm within the system to overcome this challenge and create a scalable system that can be deployed to any site without human intervention. This self-initializing technology works to automatically calibrate to the new conditions and environment to accurately count the migrating fish. In testing, the automatic adaptation algorithm was able to reduce the counting error down to the 10 to 15 percent range. The improvement in counting error with the self-initializing function means that the technology is closer to being deployable to new locations without much additional human effort. Enabling real-time management with the “Fishbox”Another challenge faced by the research team was the development of an efficient data infrastructure. In order to run the computer vision system, the video produced by sonar cameras must be delivered via the cloud or by manually mailing hard drives from a river site to the lab. These methods have notable drawbacks: a cloud-based approach is limited due to lack of internet connectivity in remote river site locations, and shipping the data introduces problems of delay. Instead of relying on these methods, the team has implemented a power-efficient computer, coined the “Fishbox,” that can be used in the field to perform the processing. The Fishbox consists of a small, lightweight computer with optimized software that fishery managers can plug into their existing laptops and sonar cameras. The system is then capable of running salmon counting models directly at the sonar sites without the need for internet connectivity. This allows managers to make hour-by-hour decisions, supporting more responsive, real-time management of salmon populations.Community developmentThe team is also working to bring a community together around monitoring for salmon fisheries management in the Pacific Northwest. “It’s just pretty exciting to have stakeholders who are enthusiastic about getting access to [our technology] as we get it to work and having a tighter integration and collaboration with them,” says Beery. “I think particularly when you’re working on food and water systems, you need direct collaboration to help facilitate impact, because you’re ensuring that what you develop is actually serving the needs of the people and organizations that you are helping to support.”This past June, Beery’s lab organized a workshop in Seattle that convened nongovernmental organizations, tribes, and state and federal departments of fish and wildlife to discuss the use of automated sonar systems to monitor and manage salmon populations. Kay notes that the workshop was an “awesome opportunity to have everybody sharing different ways that they’re using sonar and thinking about how the automated methods that we’re building could fit into that workflow.” The discussion continues now via a shared Slack channel created by the team, with over 50 participants. Convening this group is a significant achievement, as many of these organizations would not otherwise have had an opportunity to come together and collaborate. Looking forwardAs the team continues to tune the computer vision system, refine their technology, and engage with diverse stakeholders — from Indigenous communities to fishery managers — the project is poised to make significant improvements to the efficiency and accuracy of salmon monitoring and management in the region. And as Beery advances the work of her MIT group, the J-WAFS seed grant is helping to keep challenges such as fisheries management in her sights.  “The fact that the J-WAFS seed grant existed here at MIT enabled us to continue to work on this project when we moved here,” comments Beery, adding “it also expanded the scope of the project and allowed us to maintain active collaboration on what I think is a really important and impactful project.” As J-WAFS marks its 10th anniversary this year, the program aims to continue supporting and encouraging MIT faculty to pursue innovative projects that aim to advance knowledge and create practical solutions with real-world impacts on global water and food system challenges.  More

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    How climate change will impact outdoor activities in the US

    It can be hard to connect a certain amount of average global warming with one’s everyday experience, so researchers at MIT have devised a different approach to quantifying the direct impact of climate change. Instead of focusing on global averages, they came up with the concept of “outdoor days”: the number days per year in a given location when the temperature is not too hot or cold to enjoy normal outdoor activities, such as going for a walk, playing sports, working in the garden, or dining outdoors.In a study published earlier this year, the researchers applied this method to compare the impact of global climate change on different countries around the world, showing that much of the global south would suffer major losses in the number of outdoor days, while some northern countries could see a slight increase. Now, they have applied the same approach to comparing the outcomes for different parts of the United States, dividing the country into nine climatic regions, and finding similar results: Some states, especially Florida and other parts of the Southeast, should see a significant drop in outdoor days, while some, especially in the Northwest, should see a slight increase.The researchers also looked at correlations between economic activity, such as tourism trends, and changing climate conditions, and examined how numbers of outdoor days could result in significant social and economic impacts. Florida’s economy, for example, is highly dependent on tourism and on people moving there for its pleasant climate; a major drop in days when it is comfortable to spend time outdoors could make the state less of a draw.The new findings were published this month in the journal Geophysical Research Letters, in a paper by researchers Yeon-Woo Choi and Muhammad Khalifa and professor of civil and environmental engineering Elfatih Eltahir.“This is something very new in our attempt to understand impacts of climate change impact, in addition to the changing extremes,” Choi says. It allows people to see how these global changes may impact them on a very personal level, as opposed to focusing on global temperature changes or on extreme events such as powerful hurricanes or increased wildfires. “To the best of my knowledge, nobody else takes this same approach” in quantifying the local impacts of climate change, he says. “I hope that many others will parallel our approach to better understand how climate may affect our daily lives.”The study looked at two different climate scenarios — one where maximum efforts are made to curb global emissions of greenhouse gases and one “worst case” scenario where little is done and global warming continues to accelerate. They used these two scenarios with every available global climate model, 32 in all, and the results were broadly consistent across all 32 models.The reality may lie somewhere in between the two extremes that were modeled, Eltahir suggests. “I don’t think we’re going to act as aggressively” as the low-emissions scenarios suggest, he says, “and we may not be as careless” as the high-emissions scenario. “Maybe the reality will emerge in the middle, toward the end of the century,” he says.The team looked at the difference in temperatures and other conditions over various ranges of decades. The data already showed some slight differences in outdoor days from the 1961-1990 period compared to 1991-2020. The researchers then compared these most recent 30 years with the last 30 years of this century, as projected by the models, and found much greater differences ahead for some regions. The strongest effects in the modeling were seen in the Southeastern states. “It seems like climate change is going to have a significant impact on the Southeast in terms of reducing the number of outdoor days,” Eltahir says, “with implications for the quality of life of the population, and also for the attractiveness of tourism and for people who want to retire there.”He adds that “surprisingly, one of the regions that would benefit a little bit is the Northwest.” But the gain there is modest: an increase of about 14 percent in outdoor days projected for the last three decades of this century, compared to the period from 1976 to 2005. The Southwestern U.S., by comparison, faces an average loss of 23 percent of their outdoor days.The study also digs into the relationship between climate and economic activity by looking at tourism trends from U.S. National Park Service visitation data, and how that aligned with differences in climate conditions. “Accounting for seasonal variations, we find a clear connection between the number of outdoor days and the number of tourist visits in the United States,” Choi says.For much of the country, there will be little overall change in the total number of annual outdoor days, the study found, but the seasonal pattern of those days could change significantly. While most parts of the country now see the most outdoor days in summertime, that will shift as summers get hotter, and spring and fall will become the preferred seasons for outdoor activity.In a way, Eltahir says, “what we are talking about that will happen in the future [for most of the country] is already happening in Florida.” There, he says, “the really enjoyable time of year is in the spring and fall, and summer is not the best time of year.”People’s level of comfort with temperatures varies somewhat among individuals and among regions, so the researchers designed a tool, now freely available online, that allows people to set their own definitions of the lowest and highest temperatures they consider suitable for outdoor activities, and then see what the climate models predict would be the change in the number of outdoor days for their location, using their own standards of comfort. For their study, they used a widely accepted range of 10 degrees Celsius (50 degrees Fahrenheit) to 25 C (77 F), which is the “thermoneutral zone” in which the human body does not require either metabolic heat generation or evaporative cooling to maintain its core temperature — in other words, in that range there is generally no need to either shiver or sweat.The model mainly focuses on temperature but also allows people to include humidity or precipitation in their definition of what constitutes a comfortable outdoor day. The model could be extended to incorporate other variables such as air quality, but the researchers say temperature tends to be the major determinant of comfort for most people.Using their software tool, “If you disagree with how we define an outdoor day, you could define one for yourself, and then you’ll see what the impacts of that are on your number of outdoor days and their seasonality,” Eltahir says.This work was inspired by the realization, he says, that “people’s understanding of climate change is based on the assumption that climate change is something that’s going to happen sometime in the future and going to happen to someone else. It’s not going to impact them directly. And I think that contributes to the fact that we are not doing enough.”Instead, the concept of outdoor days “brings the concept of climate change home, brings it to personal everyday activities,” he says. “I hope that people will find that useful to bridge that gap, and provide a better understanding and appreciation of the problem. And hopefully that would help lead to sound policies that are based on science, regarding climate change.”The research was based on work supported by the Community Jameel for Jameel Observatory CREWSnet and Abdul Latif Jameel Water and Food Systems Lab at MIT. More

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    Pioneering the future of materials extraction

    The next time you cook pasta, imagine that you are cooking spaghetti, rigatoni, and seven other varieties all together, and they need to be separated onto 10 different plates before serving. A colander can remove the water — but you still have a mound of unsorted noodles. Now imagine that this had to be done for thousands of tons of pasta a day. That gives you an idea of the scale of the problem facing Brendan Smith PhD ’18, co-founder and CEO of SiTration, a startup formed out of MIT’s Department of Materials Science and Engineering (DMSE) in 2020. SiTration, which raised $11.8 million in seed capital led by venture capital firm 2150 earlier this month, is revolutionizing the extraction and refining of copper, cobalt, nickel, lithium, precious metals, and other materials critical to manufacturing clean-energy technologies such as electric motors, wind turbines, and batteries. Its initial target applications are recovering the materials from complex mining feed streams, spent lithium-ion batteries from electric vehicles, and various metals refining processes. The company’s breakthrough lies in a new silicon membrane technology that can be adjusted to efficiently recover disparate materials, providing a more sustainable and economically viable alternative to conventional, chemically intensive processes. Think of a colander with adjustable pores to strain different types of pasta. SiTration’s technology has garnered interest from industry players, including mining giant Rio Tinto. Some observers may question whether targeting such different industries could cause the company to lose focus. “But when you dig into these markets, you discover there is actually a significant overlap in how all of these materials are recovered, making it possible for a single solution to have impact across verticals,” Smith says.Powering up materials recoveryConventional methods of extracting critical materials in mining, refining, and recycling lithium-ion batteries involve heavy use of chemicals and heat, which harm the environment. Typically, raw ore from mines or spent batteries are ground into fine particles before being dissolved in acid or incinerated in a furnace. Afterward, they undergo intensive chemical processing to separate and purify the valuable materials. “It requires as much as 10 tons of chemical input to produce one ton of critical material recovered from the mining or battery recycling feedstock,” says Smith. Operators can then sell the recaptured materials back into the supply chain, but suffer from wide swings in profitability due to uncertain market prices. Lithium prices have been the most volatile, having surged more than 400 percent before tumbling back to near-original levels in the past two years. Despite their poor economics and negative environmental impact, these processes remain the state of the art today. By contrast, SiTration is electrifying the critical-materials recovery process, improving efficiency, producing less chemical waste, and reducing the use of chemicals and heat. What’s more, the company’s processing technology is built to be highly adaptable, so it can handle all kinds of materials. The core technology is based on work done at MIT to develop a novel type of membrane made from silicon, which is durable enough to withstand harsh chemicals and high temperatures while conducting electricity. It’s also highly tunable, meaning it can be modified or adjusted to suit different conditions or target specific materials. SiTration’s technology also incorporates electro-extraction, a technique that uses electrochemistry to further isolate and extract specific target materials. This powerful combination of methods in a single system makes it more efficient and effective at isolating and recovering valuable materials, Smith says. So depending on what needs to be separated or extracted, the filtration and electro-extraction processes are adjusted accordingly. “We can produce membranes with pore sizes from the molecular scale up to the size of a human hair in diameter, and everything in between. Combined with the ability to electrify the membrane and separate based on a material’s electrochemical properties, this tunability allows us to target a vast array of different operations and separation applications across industrial fields,” says Smith. Efficient access to materials like lithium, cobalt, and copper — and precious metals like platinum, gold, silver, palladium, and rare-earth elements — is key to unlocking innovation in business and sustainability as the world moves toward electrification and away from fossil fuels.“This is an era when new materials are critical,” says Professor Jeffrey Grossman, co-founder and chief scientist of SiTration and the Morton and Claire Goulder and Family Professor in Environmental Systems at DMSE. “For so many technologies, they’re both the bottleneck and the opportunity, offering tremendous potential for non-incremental advances. And the role they’re having in commercialization and in entrepreneurship cannot be overstated.”SiTration’s commercial frontierSmith became interested in separation technology in 2013 as a PhD student in Grossman’s DMSE research group, which has focused on the design of new membrane materials for a range of applications. The two shared a curiosity about separation of critical materials and a hunger to advance the technology. After years of study under Grossman’s mentorship, and with support from several MIT incubators and foundations including the Abdul Latif Jameel Water and Food Systems Lab’s Solutions Program, the Deshpande Center for Technological Innovation, the Kavanaugh Fellowship, MIT Sandbox, and Venture Mentoring Service, Smith was ready to officially form SiTration in 2020. Grossman has a seat on the board and plays an active role as a strategic and technical advisor. Grossman is involved in several MIT spinoffs and embraces the different imperatives of research versus commercialization. “At SiTration, we’re driving this technology to work at scale. There’s something super exciting about that goal,” he says. “The challenges that come with scaling are very different than the challenges that come in a university lab.” At the same time, although not every research breakthrough becomes a commercial product, open-ended, curiosity-driven knowledge pursuit holds its own crucial value, he adds.It has been rewarding for Grossman to see his technically gifted student and colleague develop a host of other skills the role of CEO demands. Getting out to the market and talking about the technology with potential partners, putting together a dynamic team, discovering the challenges facing industry, drumming up support, early on — those became the most pressing activities on Smith’s agenda. “What’s most fun to me about being a CEO of an early-stage startup is that there are 100 different factors, most people-oriented, that you have to navigate every day. Each stakeholder has different motivations and objectives. And you basically try to fit that all together, to create value for our partners and customers, the company, and for society,” says Smith. “You start with just an idea, and you have to keep leveraging that to form a more and more tangible product, to multiply and progress commercial relationships, and do it all at an ever-expanding scale.” MIT DNA runs deep in the nine-person company, with DMSE grad and former Grossman student Jatin Patil as director of product; Ahmed Helal, from MIT’s Department of Mechanical Engineering, as vice president of research and development; Daniel Bregante, from the Department of Chemistry, as VP of technology; and Sarah Melvin, from the departments of Physics and Political Science, as VP of strategy and operations. Melvin is the first hire devoted to business development. Smith plans to continue expanding the team following the closing of the company’s seed round.  Strategic alliancesBeing a good communicator was important when it came to securing funding, Smith says. SiTration received $2.35 million in pre-seed funding in 2022 led by Azolla Ventures, which reserves its $239 million in investment capital for startups that would not otherwise easily obtain funding. “We invest only in solution areas that can achieve gigaton-scale climate impact by 2050,” says Matthew Nordan, a general partner at Azolla and now SiTration board member. The MIT-affiliated E14 Fund also contributed to the pre-seed round; Azolla and E14 both participated in the recent seed funding round. “Brendan demonstrated an extraordinary ability to go from being a thoughtful scientist to a business leader and thinker who has punched way above his weight in engaging with customers and recruiting a well-balanced team and navigating tricky markets,” says Nordan. One of SiTration’s first partnerships is with Rio Tinto, one of the largest mining companies in the world. As SiTration evaluated various uses cases in its early days, identifying critical materials as its target market, Rio Tinto was looking for partners to recover valuable metals such as cobalt and copper from the wastewater generated at mines. These metals were typically trapped in the water, creating harmful waste and resulting in lost revenue. “We thought this was a great innovation challenge and posted it on our website to scout for companies to partner with who can help us solve this water challenge,” said Nick Gurieff, principal advisor for mine closure, in an interview with MIT’s Industrial Liaison Program in 2023. At SiTration, mining was not yet a market focus, but Smith couldn’t help noticing that Rio Tinto’s needs were in alignment with what his young company offered. SiTration submitted its proposal in August 2022. Gurieff said SiTration’s tunable membrane set it apart. The companies formed a business partnership in June 2023, with SiTration adjusting its membrane to handle mine wastewater and incorporating Rio Tinto feedback to refine the technology. After running tests with water from mine sites, SiTration will begin building a small-scale critical-materials recovery unit, followed by larger-scale systems processing up to 100 cubic meters of water an hour.SiTration’s focused technology development with Rio Tinto puts it in a good position for future market growth, Smith says. “Every ounce of effort and resource we put into developing our product is geared towards creating real-world value. Having an industry-leading partner constantly validating our progress is a tremendous advantage.”It’s a long time from the days when Smith began tinkering with tiny holes in silicon in Grossman’s DMSE lab. Now, they work together as business partners who are scaling up technology to meet a global need. Their joint passion for applying materials innovation to tough problems has served them well. “Materials science and engineering is an engine for a lot of the innovation that is happening today,” Grossman says. “When you look at all of the challenges we face to make the transition to a more sustainable planet, you realize how many of these are materials challenges.” More

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    Researchers develop a detector for continuously monitoring toxic gases

    Most systems used to detect toxic gases in industrial or domestic settings can be used only once, or at best a few times. Now, researchers at MIT have developed a detector that could provide continuous monitoring for the presence of these gases, at low cost.The new system combines two existing technologies, bringing them together in a way that preserves the advantages of each while avoiding their limitations. The team used a material called a metal-organic framework, or MOF, which is highly sensitive to tiny traces of gas but whose performance quickly degrades, and combined it with a polymer material that is highly durable and easier to process, but much less sensitive.The results are reported today in the journal Advanced Materials, in a paper by MIT professors Aristide Gumyusenge, Mircea Dinca, Heather Kulik, and Jesus del Alamo, graduate student Heejung Roh, and postdocs Dong-Ha Kim, Yeongsu Cho, and Young-Moo Jo.Highly porous and with large surface areas, MOFs come in a variety of compositions. Some can be insulators, but the ones used for this work are highly electrically conductive. With their sponge-like form, they are effective at capturing molecules of various gases, and the sizes of their pores can be tailored to make them selective for particular kinds of gases. “If you are using them as a sensor, you can recognize if the gas is there if it has an effect on the resistivity of the MOF,” says Gumyusenge, the paper’s senior author and the Merton C. Flemings Career Development Assistant Professor of Materials Science and Engineering.The drawback for these materials’ use as detectors for gases is that they readily become saturated, and then can no longer detect and quantify new inputs. “That’s not what you want. You want to be able to detect and reuse,” Gumyusenge says. “So, we decided to use a polymer composite to achieve this reversibility.”The team used a class of conductive polymers that Gumyusenge and his co-workers had previously shown can respond to gases without permanently binding to them. “The polymer, even though it doesn’t have the high surface area that the MOFs do, will at least provide this recognize-and-release type of phenomenon,” he says.The team combined the polymers in a liquid solution along with the MOF material in powdered form, and deposited the mixture on a substrate, where they dry into a uniform, thin coating. By combining the polymer, with its quick detection capability, and the more sensitive MOFs, in a one-to-one ratio, he says, “suddenly we get a sensor that has both the high sensitivity we get from the MOF and the reversibility that is enabled by the presence of the polymer.”The material changes its electrical resistance when molecules of the gas are temporarily trapped in the material. These changes in resistance can be continuously monitored by simply attaching an ohmmeter to track the resistance over time. Gumyusenge and his students demonstrated the composite material’s ability to detect nitrogen dioxide, a toxic gas produced by many kinds of combustion, in a small lab-scale device. After 100 cycles of detection, the material was still maintaining its baseline performance within a margin of about 5 to 10 percent, demonstrating its long-term use potential.In addition, this material has far greater sensitivity than most presently used detectors for nitrogen dioxide, the team reports. This gas is often detected after the use of stove ovens. And, with this gas recently linked to many asthma cases in the U.S., reliable detection in low concentrations is important. The team demonstrated that this new composite could detect, reversibly, the gas at concentrations as low as 2 parts per million.While their demonstration was specifically aimed at nitrogen dioxide, Gumyusenge says, “we can definitely tailor the chemistry to target other volatile molecules,” as long as they are small polar analytes, “which tend to be most of the toxic gases.”Besides being compatible with a simple hand-held detector or a smoke-alarm type of device, one advantage of the material is that the polymer allows it to be deposited as an extremely thin uniform film, unlike regular MOFs, which are generally in an inefficient powder form. Because the films are so thin, there is little material needed and production material costs could be low; the processing methods could be typical of those used for industrial coating processes. “So, maybe the limiting factor will be scaling up the synthesis of the polymers, which we’ve been synthesizing in small amounts,” Gumyusenge says.“The next steps will be to evaluate these in real-life settings,” he says. For example, the material could be applied as a coating on chimneys or exhaust pipes to continuously monitor gases through readings from an attached resistance monitoring device. In such settings, he says, “we need tests to check if we truly differentiate it from other potential contaminants that we might have overlooked in the lab setting. Let’s put the sensors out in real-world scenarios and see how they do.”The work was supported by the MIT Climate and Sustainability Consortium (MCSC), the Abdul Latif Jameel Water and Food Systems Lab (J-WAFS) at MIT, and the U.S. Department of Energy. More

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    Repurposed beer yeast may offer a cost-effective way to remove lead from water

    Every year, beer breweries generate and discard thousands of tons of surplus yeast. Researchers from MIT and Georgia Tech have now come up with a way to repurpose that yeast to absorb lead from contaminated water.Through a process called biosorption, yeast can quickly absorb even trace amounts of lead and other heavy metals from water. The researchers showed that they could package the yeast inside hydrogel capsules to create a filter that removes lead from water. Because the yeast cells are encapsulated, they can be easily removed from the water once it’s ready to drink.“We have the hydrogel surrounding the free yeast that exists in the center, and this is porous enough to let water come in, interact with yeast as if they were freely moving in water, and then come out clean,” says Patricia Stathatou, a former postdoc at the MIT Center for Bits and Atoms, who is now a research scientist at Georgia Tech and an incoming assistant professor at Georgia Tech’s School of Chemical and Biomolecular Engineering. “The fact that the yeast themselves are bio-based, benign, and biodegradable is a significant advantage over traditional technologies.”The researchers envision that this process could be used to filter drinking water coming out of a faucet in homes, or scaled up to treat large quantities of water at treatment plants.MIT graduate student Devashish Gokhale and Stathatou are the lead authors of the study, which appears today in the journal RSC Sustainability. Patrick Doyle, the Robert T. Haslam Professor of Chemical Engineering at MIT, is the senior author of the paper, and Christos Athanasiou, an assistant professor of aerospace engineering at Georgia Tech and a former visiting scholar at MIT, is also an author.Absorbing leadThe new study builds on work that Stathatou and Athanasiou began in 2021, when Athanasiou was a visiting scholar at MIT’s Center for Bits and Atoms. That year, they calculated that waste yeast discarded from a single brewery in Boston would be enough to treat the city’s entire water supply.Through biosorption, a process that is not fully understood, yeast cells can bind to and absorb heavy metal ions, even at challenging initial concentrations below 1 part per million. The MIT team found that this process could effectively decontaminate water with low concentrations of lead. However, one key obstacle remained, which was how to remove yeast from the water after they absorb the lead.In a serendipitous coincidence, Stathatou and Athanasiou happened to present their research at the AIChE Annual Meeting in Boston in 2021, where Gokhale, a student in Doyle’s lab, was presenting his own research on using hydrogels to capture micropollutants in water. The two sets of researchers decided to join forces and explore whether the yeast-based strategy could be easier to scale up if the yeast were encapsulated in hydrogels developed by Gokhale and Doyle.“What we decided to do was make these hollow capsules — something like a multivitamin pill, but instead of filling them up with vitamins, we fill them up with yeast cells,” Gokhale says. “These capsules are porous, so the water can go into the capsules and the yeast are able to bind all of that lead, but the yeast themselves can’t escape into the water.”The capsules are made from a polymer called polyethylene glycol (PEG), which is widely used in medical applications. To form the capsules, the researchers suspend freeze-dried yeast in water, then mix them with the polymer subunits. When UV light is shone on the mixture, the polymers link together to form capsules with yeast trapped inside.Each capsule is about half a millimeter in diameter. Because the hydrogels are very thin and porous, water can easily pass through and encounter the yeast inside, while the yeast remain trapped.In this study, the researchers showed that the encapsulated yeast could remove trace lead from water just as rapidly as the unencapsulated yeast from Stathatou and Athanasiou’s original 2021 study.Scaling upLed by Athanasiou, the researchers tested the mechanical stability of the hydrogel capsules and found that the capsules and the yeast inside can withstand forces similar to those generated by water running from a faucet. They also calculated that the yeast-laden capsules should be able to withstand forces generated by flows in water treatment plants serving several hundred residences.“Lack of mechanical robustness is a common cause of failure of previous attempts to scale-up biosorption using immobilized cells; in our work we wanted to make sure that this aspect is thoroughly addressed from the very beginning to ensure scalability,” Athanasiou says.After assessing the mechanical robustness of the yeast-laden capsules, the researchers constructed a proof-of-concept packed-bed biofilter, capable of treating trace lead-contaminated water and meeting U.S. Environmental Protection Agency drinking water guidelines while operating continuously for 12 days.This process would likely consume less energy than existing physicochemical processes for removing trace inorganic compounds from water, such as precipitation and membrane filtration, the researchers say.This approach, rooted in circular economy principles, could minimize waste and environmental impact while also fostering economic opportunities within local communities. Although numerous lead contamination incidents have been reported in various locations in the United States, this approach could have an especially significant impact in low-income areas that have historically faced environmental pollution and limited access to clean water, and may not be able to afford other ways to remediate it, the researchers say.“We think that there’s an interesting environmental justice aspect to this, especially when you start with something as low-cost and sustainable as yeast, which is essentially available anywhere,” Gokhale says.The researchers are now exploring strategies for recycling and replacing the yeast once they’re used up, and trying to calculate how often that will need to occur. They also hope to investigate whether they could use feedstocks derived from biomass to make the hydrogels, instead of fossil-fuel-based polymers, and whether the yeast can be used to capture other types of contaminants.“Moving forward, this is a technology that can be evolved to target other trace contaminants of emerging concern, such as PFAS or even microplastics,” Stathatou says. “We really view this as an example with a lot of potential applications in the future.”The research was funded by the Rasikbhai L. Meswani Fellowship for Water Solutions, the MIT Abdul Latif Jameel Water and Food Systems Lab (J-WAFS), and the Renewable Bioproducts Institute at Georgia Tech. More

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    Microbes could help reduce the need for chemical fertilizers

    Production of chemical fertilizers accounts for about 1.5 percent of the world’s greenhouse gas emissions. MIT chemists hope to help reduce that carbon footprint by replacing some chemical fertilizer with a more sustainable source — bacteria.

    Bacteria that can convert nitrogen gas to ammonia could not only provide nutrients that plants need, but also help regenerate soil and protect plants from pests. However, these bacteria are sensitive to heat and humidity, so it’s difficult to scale up their manufacture and ship them to farms.

    To overcome that obstacle, MIT chemical engineers have devised a metal-organic coating that protects bacterial cells from damage without impeding their growth or function. In a new study, they found that these coated bacteria improved the germination rate of a variety of seeds, including vegetables such as corn and bok choy.

    This coating could make it much easier for farmers to deploy microbes as fertilizers, says Ariel Furst, the Paul M. Cook Career Development Assistant Professor of Chemical Engineering at MIT and the senior author of the study.

    “We can protect them from the drying process, which would allow us to distribute them much more easily and with less cost because they’re a dried powder instead of in liquid,” she says. “They can also withstand heat up to 132 degrees Fahrenheit, which means that you wouldn’t have to use cold storage for these microbes.”

    Benjamin Burke ’23 and postdoc Gang Fan are the lead authors of the open-access paper, which appears in the Journal of the American Chemical Society Au. MIT undergraduate Pris Wasuwanich and Evan Moore ’23 are also authors of the study.

    Protecting microbes

    Chemical fertilizers are manufactured using an energy-intensive process known as Haber-Bosch, which uses extremely high pressures to combine nitrogen from the air with hydrogen to make ammonia.

    In addition to the significant carbon footprint of this process, another drawback to chemical fertilizers is that long-term use eventually depletes the nutrients in the soil. To help restore soil, some farmers have turned to “regenerative agriculture,” which uses a variety of strategies, including crop rotation and composting, to keep soil healthy. Nitrogen-fixing bacteria, which convert nitrogen gas to ammonia, can aid in this approach.

    Some farmers have already begun deploying these “microbial fertilizers,” growing them in large onsite fermenters before applying them to the soil. However, this is cost-prohibitive for many farmers.

    Shipping these bacteria to rural areas is not currently a viable option, because they are susceptible to heat damage. The microbes are also too delicate to survive the freeze-drying process that would make them easier to transport.

    To protect the microbes from both heat and freeze-drying, Furst decided to apply a coating called a metal-phenol network (MPN), which she has previously developed to encapsulate microbes for other uses, such as protecting therapeutic bacteria delivered to the digestive tract.

    The coatings contain two components — a metal and an organic compound called a polyphenol — that can self-assemble into a protective shell. The metals used for the coatings, including iron, manganese, aluminum, and zinc, are considered safe as food additives. Polyphenols, which are often found in plants, include molecules such as tannins and other antioxidants. The FDA classifies many of these polyphenols as GRAS (generally regarded as safe).

    “We are using these natural food-grade compounds that are known to have benefits on their own, and then they form these little suits of armor that protect the microbes,” Furst says.

    For this study, the researchers created 12 different MPNs and used them to encapsulate Pseudomonas chlororaphis, a nitrogen-fixing bacterium that also protects plants against harmful fungi and other pests. They found that all of the coatings protected the bacteria from temperatures up to 50 degrees Celsius (122 degrees Fahrenheit), and also from relative humidity up to 48 percent. The coatings also kept the microbes alive during the freeze-drying process.

    A boost for seeds

    Using microbes coated with the most effective MPN — a combination of manganese and a polyphenol called epigallocatechin gallate (EGCG) — the researchers tested their ability to help seeds germinate in a lab dish. They heated the coated microbes to 50 C before placing them in the dish, and compared them to fresh uncoated microbes and freeze-dried uncoated microbes.

    The researchers found that the coated microbes improved the seeds’ germination rate by 150 percent, compared to seeds treated with fresh, uncoated microbes. This result was consistent across several different types of seeds, including dill, corn, radishes, and bok choy.

    Furst has started a company called Seia Bio to commercialize the coated bacteria for large-scale use in regenerative agriculture. She hopes that the low cost of the manufacturing process will help make microbial fertilizers accessible to small-scale farmers who don’t have the fermenters needed to grow such microbes.

    “When we think about developing technology, we need to intentionally design it to be inexpensive and accessible, and that’s what this technology is. It would help democratize regenerative agriculture,” she says.

    The research was funded by the Army Research Office, a National Institutes of Health New Innovator Award, a National Institute for Environmental Health Sciences Core Center Grant, the CIFAR Azrieli Global Scholars Program, the MIT J-WAFS Program, the MIT Climate and Sustainability Consortium, and the MIT Deshpande Center. More

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    Tiny magnetic beads produce an optical signal that could be used to quickly detect pathogens

    Getting results from a blood test can take anywhere from one day to a week, depending on what a test is targeting. The same goes for tests of water pollution and food contamination. And in most cases, the wait time has to do with time-consuming steps in sample processing and analysis.

    Now, MIT engineers have identified a new optical signature in a widely used class of magnetic beads, which could be used to quickly detect contaminants in a variety of diagnostic tests. For example, the team showed the signature could be used to detect signs of the food contaminant Salmonella.

    The so-called Dynabeads are microscopic magnetic beads that can be coated with antibodies that bind to target molecules, such as a specific pathogen. Dynabeads are typically used in experiments in which they are mixed into solutions to capture molecules of interest. But from there, scientists have to take additional, time-consuming steps to confirm that the molecules are indeed present and bound to the beads.

    The MIT team found a faster way to confirm the presence of Dynabead-bound pathogens, using optics, specifically, Raman spectroscopy. This optical technique identifies specific molecules based on their “Raman signature,” or the unique way in which a molecule scatters light.

    The researchers found that Dynabeads have an unusually strong Raman signature that can be easily detected, much like a fluorescent tag. This signature, they found, can act as a “reporter.” If detected, the signal can serve as a quick confirmation, within less than one second, that a target pathogen is indeed present in a given sample. The team is currently working to develop a portable device for quickly detecting a range of bacterial pathogens, and their results will appear in an Emerging Investigators special issue of the Journal of Raman Spectroscopy.

    “This technique would be useful in a situation where a doctor is trying to narrow down the source of an infection in order to better inform antibiotic prescription, as well as for the detection of known pathogens in food and water,” says study co-author Marissa McDonald, a graduate student in the Harvard-MIT Program in Health Sciences and Technology. “Additionally, we hope this approach will eventually lead to expanded access to advanced diagnostics in resource-limited environments.”

    Study co-authors at MIT include Postdoctoral Associate Jongwan Lee; Visiting Scholar Nikiwe Mhlanga; Research Scientist Jeon Woong Kang; Tata Professor Rohit Karnik, who is also the associate director of the Abdul Latif Jameel Water and Food Systems Lab; and Assistant Professor Loza Tadesse of the Department of Mechanical Engineering.

    Oil and water

    Looking for diseased cells and pathogens in fluid samples is an exercise in patience.

    “It’s kind of a needle-in-a-haystack problem,” Tadesse says.

    The numbers present are so small that they must be grown in controlled environments to sufficient numbers, and their cultures stained, then studied under a microscope. The entire process can take several days to a week to yield a confident positive or negative result.

    Both Karnik and Tadesse’s labs have independently been developing techniques to speed up various parts of the pathogen testing process and make the process portable, using Dynabeads.

    Dynabeads are commercially available microscopic beads made from a magnetic iron core and a polymer shell that can be coated with antibodies. The surface antibodies act as hooks to bind specific target molecules. When mixed with a fluid, such as a vial of blood or water, any molecules present will glom onto the Dynabeads. Using a magnet, scientists can gently coax the beads to the bottom of a vial and filter them out of a solution. Karnik’s lab is investigating ways to then further separate the beads into those that are bound to a target molecule, and those that are not. “Still, the challenge is, how do we know that we have what we’re looking for?” Tadesse says.

    The beads themselves are not visible by eye. That’s where Tadesse’s work comes in. Her lab uses Raman spectroscopy as a way to “fingerprint” pathogens. She has found that different cell types scatter light in unique ways that can be used as a signature to identify them.

    In the team’s new work, she and her colleagues found that Dynabeads also have a unique and strong Raman signature that can act as a surprisingly clear beacon.

    “We were initially seeking to identify the signatures of bacteria, but the signature of the Dynabeads was actually very strong,” Tadesse says. “We realized this signal could be a means of reporting to you whether you have that bacteria or not.”

    Testing beacon

    As a practical demonstration, the researchers mixed Dynabeads into vials of water contaminated with Salmonella. They then magnetically isolated these beads onto microscope slides and measured the way light scattered through the fluid when exposed to laser light. Within half a second, they quickly detected the Dynabeads’ Raman signature — a confirmation that bound Dynabeads, and by inference, Salmonella, were present in the fluid.

    “This is something that can be used to rapidly give a positive or negative answer: Is there a contaminant or not?” Tadesse says. “Because even a handful of pathogens can cause clinical symptoms.”

    The team’s new technique is significantly faster than conventional methods and uses elements that could be adapted into smaller, more portable forms — a goal that the researchers are currently working toward. The approach is also highly versatile.

    “Salmonella is the proof of concept,” Tadesse says. “You could purchase Dynabeads with E.coli antibodies, and the same thing would happen: It would bind to the bacteria, and we’d be able to detect the Dynabead signature because the signal is super strong.”

    The team is particularly keen to apply the test to conditions such as sepsis, where time is of the essence, and where pathogens that trigger the condition are not rapidly detected using conventional lab tests.

    “There are a lot cases, like in sepsis, where pathogenic cells cannot always be grown on a plate,” says Lee, a member of Karnik’s lab. “In that case, our technique could rapidly detect these pathogens.”

    This research was supported, in part, by the MIT Laser Biomedical Research Center, the National Cancer Institute, and the Abdul Latif Jameel Water and Food Systems Lab at MIT. More