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    MIT chemists boost the efficiency of a key enzyme in photosynthesis

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    During photosynthesis, an enzyme called rubisco catalyzes a key reaction — the incorporation of carbon dioxide into organic compounds to create sugars. However, rubisco, which is believed to be the most abundant enzyme on Earth, is very inefficient compared to the other enzymes involved in photosynthesis.MIT chemists have now shown that they can greatly enhance a version of rubisco found in bacteria from a low-oxygen environment. Using a process known as directed evolution, they identified mutations that could boost rubisco’s catalytic efficiency by up to 25 percent.The researchers now plan to apply their technique to forms of rubisco that could be used in plants to help boost their rates of photosynthesis, which could potentially improve crop yields.“This is, I think, a compelling demonstration of successful improvement of a rubisco’s enzymatic properties, holding out a lot of hope for engineering other forms of rubisco,” says Matthew Shoulders, the Class of 1942 Professor of Chemistry at MIT.Shoulders and Robert Wilson, a research scientist in the Department of Chemistry, are the senior authors of the new study, which appears this week in the Proceedings of the National Academy of Sciences. MIT graduate student Julie McDonald is the paper’s lead author.Evolution of efficiencyWhen plants or photosynthetic bacteria absorb energy from the sun, they first convert it into energy-storing molecules such as ATP. In the next phase of photosynthesis, cells use that energy to transform a molecule known as ribulose bisphosphate into glucose, which requires several additional reactions. Rubisco catalyzes the first of those reactions, known as carboxylation. During that reaction, carbon from CO2 is added to ribulose bisphosphate.Compared to the other enzymes involved in photosynthesis, rubisco is very slow, catalyzing only one to 10 reactions per second. Additionally, rubisco can also interact with oxygen, leading to a competing reaction that incorporates oxygen instead of carbon — a process that wastes some of the energy absorbed from sunlight.“For protein engineers, that’s a really attractive set of problems because those traits seem like things that you could hopefully make better by making changes to the enzyme’s amino acid sequence,” McDonald says.Previous research has led to improvement in rubisco’s stability and solubility, which resulted in small gains in enzyme efficiency. Most of those studies used directed evolution — a technique in which a naturally occurring protein is randomly mutated and then screened for the emergence of new, desirable features.This process is usually done using error-prone PCR, a technique that first generates mutations in vitro (outside of the cell), typically introducing only one or two mutations in the target gene. In past studies on rubisco, this library of mutations was then introduced into bacteria that grow at a rate relative to rubisco activity. Limitations in error-prone PCR and in the efficiency of introducing new genes restrict the total number of mutations that can be generated and screened using this approach. Manual mutagenesis and selection steps also add more time to the process over multiple rounds of evolution.The MIT team instead used a newer mutagenesis technique that the Shoulders Lab previously developed, called MutaT7. This technique allows the researchers to perform both mutagenesis and screening in living cells, which dramatically speeds up the process. Their technique also enables them to mutate the target gene at a higher rate.“Our continuous directed evolution technique allows you to look at a lot more mutations in the enzyme than has been done in the past,” McDonald says.Better rubiscoFor this study, the researchers began with a version of rubisco, isolated from a family of semi-anaerobic bacteria known as Gallionellaceae, that is one of the fastest rubisco found in nature. During the directed evolution experiments, which were conducted in E. coli, the researchers kept the microbes in an environment with atmospheric levels of oxygen, creating evolutionary pressure to adapt to oxygen.After six rounds of directed evolution, the researchers identified three different mutations that improved the rubisco’s resistance to oxygen. Each of these mutations are located near the enzyme’s active site (where it performs carboxylation or oxygenation). The researchers believe that these mutations improve the enzyme’s ability to preferentially interact with carbon dioxide over oxygen, which leads to an overall increase in carboxylation efficiency.“The underlying question here is: Can you alter and improve the kinetic properties of rubisco to operate better in environments where you want it to operate better?” Shoulders says. “What changed through the directed evolution process was that rubisco began to like to react with oxygen less. That allows this rubisco to function well in an oxygen-rich environment, where normally it would constantly get distracted and react with oxygen, which you don’t want it to do.”In ongoing work, the researchers are applying this approach to other forms of rubisco, including rubisco from plants. Plants are believed to lose about 30 percent of the energy from the sunlight they absorb through a process called photorespiration, which occurs when rubisco acts on oxygen instead of carbon dioxide.“This really opens the door to a lot of exciting new research, and it’s a step beyond the types of engineering that have dominated rubisco engineering in the past,” Wilson says. “There are definite benefits to agricultural productivity that could be leveraged through a better rubisco.”The research was funded, in part, by the National Science Foundation, the National Institutes of Health, an Abdul Latif Jameel Water and Food Systems Lab Grand Challenge grant, and a Martin Family Society Fellowship for Sustainability. More

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      Study shows how a common fertilizer ingredient benefits plants

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      Lanthanides are a class of rare earth elements that in many countries are added to fertilizer as micronutrients to stimulate plant growth. But little is known about how they are absorbed by plants or influence photosynthesis, potentially leaving their benefits untapped.Now, researchers from MIT have shed light on how lanthanides move through and operate within plants. These insights could help farmers optimize their use to grow some of the world’s most popular crops.Published today in the Journal of the American Chemical Society, the study shows that a single nanoscale dose of lanthanides applied to seeds can make some of the world’s most common crops more resilient to UV stress. The researchers also uncovered the chemical processes by which lanthanides interact with the chlorophyll pigments that drive photosynthesis, showing that different lanthanide elements strengthen chlorophyll by replacing the magnesium at its center.“This is a first step to better understand how these elements work in plants, and to provide an example of how they could be better delivered to plants, compared to simply applying them in the soil,” says Associate Professor Benedetto Marelli, who conducted the research with postdoc Giorgio Rizzo. “This is the first example of a thorough study showing the effects of lanthanides on chlorophyll, and their beneficial effects to protect plants from UV stress.”Inside plant connectionsCertain lanthanides are used as contrast agents in MRI and for applications including light-emitting diodes, solar cells, and lasers. Over the last 50 years, lanthanides have become increasingly used in agriculture to enhance crop yields, with China alone applying lanthanide-based fertilizers to nearly 4 million hectares of land each year.“Lanthanides have been considered for a long time to be biologically irrelevant, but that’s changed in agriculture, especially in China,” says Rizzo, the paper’s first author. “But we largely don’t know how lanthanides work to benefit plants — nor do we understand their uptake mechanisms from plant tissues.”Recent studies have shown that low concentrations of lanthanides can promote plant growth, root elongation, hormone synthesis, and stress tolerance, but higher doses can cause harm to plants. Striking the right balance has been hard because of our lack of understanding around how lanthanides are absorbed by plants or how they interact with root soil.For the study, the researchers leveraged seed coating and treatment technologies they previously developed to investigate the way the plant pigment chlorophyll interacts with lanthanides, both inside and outside of plants. Up until now, researchers haven’t been sure whether chlorophyll interacts with lanthanide ions at all.Chlorophyll drives photosynthesis, but the pigments lose their ability to efficiently absorb light when the magnesium ion at their core is removed. The researchers discovered that lanthanides can fill that void, helping chlorophyll pigments partially recover some of their optical properties in a process known as re-greening.“We found that lanthanides can boost several parameters of plant health,” Marelli says. “They mostly accumulate in the roots, but a small amount also makes its way to the leaves, and some of the new chlorophyll molecules made in leaves have lanthanides incorporated in their structure.”This study also offers the first experimental evidence that lanthanides can increase plant resilience to UV stress, something the researchers say was completely unexpected.“Chlorophylls are very sensitive pigments,” Rizzo says. “They can convert light to energy in plants, but when they are isolated from the cell structure, they rapidly hydrolyze and degrade. However, in the form with lanthanides at their center, they are pretty stable, even after extracting them from plant cells.”The researchers, using different spectroscopic techniques, found the benefits held across a range of staple crops, including chickpea, barley, corn, and soybeans.The findings could be used to boost crop yield and increase the resilience of some of the world’s most popular crops to extreme weather.“As we move into an environment where extreme heat and extreme climate events are more common, and particularly where we can have prolonged periods of sun in the field, we want to provide new ways to protect our plants,” Marelli says. “There are existing agrochemicals that can be applied to leaves for protecting plants from stressors such as UV, but they can be toxic, increase microplastics, and can require multiple applications. This could be a complementary way to protect plants from UV stress.”Identifying new applicationsThe researchers also found that larger lanthanide elements like lanthanum were more effective at strengthening chlorophyll pigments than smaller ones. Lanthanum is considered a low-value byproduct of rare earths mining, and can become a burden to the rare earth element (REE) supply chain due to the need to separate it from more desirable rare earths. Increasing the demand for lanthanum could diversify the economics of REEs and improve the stability of their supply chain, the scientists suggest.“This study shows what we could do with these lower-value metals,” Marelli says. “We know lanthanides are extremely useful in electronics, magnets, and energy. In the U.S., there’s a big push to recycle them. That’s why for the plant studies, we focused on lanthanum, being the most abundant, cheapest lanthanide ion.”Moving forward, the team plans to explore how lanthanides work with other biological molecules, including proteins in the human body.In agriculture, the team hopes to scale up its research to include field and greenhouse studies to continue testing the results of UV resilience on different crop types and in experimental farm conditions.“Lanthanides are already widely used in agriculture,” Rizzo says. “We hope this study provides evidence that allows more conscious use of them and also a new way to apply them through seed treatments.”The research was supported by the MIT Climate Grand Challenge and the Office for Naval Research. More

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      in Environment

      Students and staff work together for MIT’s first “No Mow May”

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      In recent years, some grass lawns around the country have grown a little taller in springtime thanks to No Mow May, a movement originally launched by U.K. nonprofit Plantlife in 2019 designed to raise awareness about the ecological impacts of the traditional, resource-intensive, manicured grass lawn. No Mow May encourages people to skip spring mowing to allow for grass to grow tall and provide food and shelter for beneficial creatures including bees, beetles, and other pollinators.This year, MIT took part in the practice for the first time, with portions of the Kendall/MIT Open Space, Bexley Garden, and the Tang Courtyard forgoing mowing from May 1 through June 6 to make space for local pollinators, decrease water use, and encourage new thinking about the traditional lawn. MIT’s first No Mow May was the result of championing by the Graduate Student Council Sustainability Subcommittee (GSC Sustain) and made possible by the Office of the Vice Provost for Campus Space Management and Planning. A student idea sproutsDespite being a dense urban campus, MIT has no shortage of green spaces — from pocket gardens and community-managed vegetable plots to thousands of shade trees — and interest in these spaces continues to grow. In recent years, student-led initiatives supported by Institute leadership and operational staff have transformed portions of campus by increasing the number of native pollinator plants and expanding community gardens, like the Hive Garden. With No Mow May, these efforts stepped out of the garden and into MIT’s many grassy open spaces. “The idea behind it was to raise awareness for more sustainable and earth-friendly lawn practices,” explains Gianmarco Terrones, GSC Sustain member. Those practices include reducing the burden of mowing, limiting use of fertilizers, and providing shelter and food for pollinators. “The insects that live in these spaces are incredibly important in terms of pollination, but they’re also part of the food chain for a lot of animals,” says Terrones. Research has shown that holding off on mowing in spring, even in small swaths of green space, can have an impact. The early months of spring have the lowest number of flowers in regions like New England, and providing a resource and refuge — even for a short duration — can support fragile pollinators like bees. Additionally, No Mow May aims to help people rethink their yards and practices, which are not always beneficial for local ecosystems. Signage at each No Mow site on campus highlighted information on local pollinators, the impact of the project, and questions for visitors to ask themselves. “Having an active sign there to tell people, ‘look around. How many butterflies do you see after six weeks of not mowing? Do you see more? Do you see more bees?’ can cause subtle shifts in people’s awareness of ecosystems,” says GSC Sustain member Mingrou Xie. A mowed barrier around each project also helped visitors know that areas of tall grass at No Mow sites are intentional.Campus partners bring sustainable practices to lifeTo make MIT’s No Mow May possible, GSC Sustain members worked with the Office of the Vice Provost and the Open Space Working Group, co-chaired by Vice Provost for Campus Space Management and Planning Brent Ryan and Director of Sustainability Julie Newman. The Working Group, which also includes staff from Open Space Programming, Campus Planning, and faculty in the School of Architecture and Planning, helped to identify potential No Mow locations and develop strategies for educational signage and any needed maintenance. “Massachusetts is a biodiverse state, and No Mow May provides an exciting opportunity for MIT to support that biodiversity on its own campus,” says Ryan. Students were eager for space on campus with high visibility, and the chosen locations of the Kendall/MIT Open Space, Bexley Garden, and the Tang Courtyard fit the bill. “We wanted to set an example and empower the community to feel like they can make a positive change to an environment they spend so much time in,” says Xie. For GSC Sustain, that positive change also takes the form of the Native Plant Project, which they launched in 2022 to increase the number of Massachusetts-native pollinator plants on campus — plants like swamp milkweed, zigzag goldenrod, big leaf aster, and red columbine, with which native pollinators have co-evolved. Partnering with the Open Space Working Group, GSC Sustain is currently focused on two locations for new native plant gardens — the President’s Garden and the terrace gardens at the E37 Graduate Residence. “Our short-term goal is to increase the number of native [plants] on campus, but long term we want to foster a community of students and staff interested in supporting sustainable urban gardening,” says Xie.Campus as a test bed continues to growAfter just a few weeks of growing, the campus No Mow May locations sprouted buttercups, mouse ear chickweed, and small tree saplings, highlighting the diversity waiting dormant in the average lawn. Terrones also notes other discoveries: “It’s been exciting to see how much the grass has sprung up these last few weeks. I thought the grass would all grow at the same rate, but as May has gone on the variations in grass height have become more apparent, leading to non-uniform lawns with a clearly unmanicured feel,” he says. “We hope that members of MIT noticed how these lawns have evolved over the span of a few weeks and are inspired to implement more earth-friendly lawn practices in their own homes/spaces.”No Mow May and the Native Plant Project fit into MIT’s overall focus on creating resilient ecosystems that support and protect the MIT community and the beneficial critters that call it home. MIT Grounds Services has long included native plants in the mix of what is grown on campus and native pollinator gardens, like the Hive Garden, have been developed and cared for through partnerships with students and Grounds Services in recent years. Grounds, along with consultants that design and install our campus landscape projects, strive to select plants that assist us with meeting sustainability goals, like helping with stormwater runoff and cooling. No Mow May can provide one more data point for the iterative process of choosing the best plants and practices for a unique microclimate like the MIT campus.“We are always looking for new ways to use our campus as a test bed for sustainability,” says Director of Sustainability Julie Newman. “Community-led projects like No Mow May help us to learn more about our campus and share those lessons with the larger community.”The Office of the Vice Provost, the Open Space Working Group, and GSC Sustain will plan to reconnect in the fall for a formal debrief of the project and its success. Given the positive community feedback, future possibilities of expanding or extending No Mow May will be discussed. More

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      Universal nanosensor unlocks the secrets to plant growth

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      Researchers from the Disruptive and Sustainable Technologies for Agricultural Precision (DiSTAP) interdisciplinary research group within the Singapore-MIT Alliance for Research and Technology have developed the world’s first near-infrared fluorescent nanosensor capable of real-time, nondestructive, and species-agnostic detection of indole-3-acetic acid (IAA) — the primary bioactive auxin hormone that controls the way plants develop, grow, and respond to stress.Auxins, particularly IAA, play a central role in regulating key plant processes such as cell division, elongation, root and shoot development, and response to environmental cues like light, heat, and drought. External factors like light affect how auxin moves within the plant, temperature influences how much is produced, and a lack of water can disrupt hormone balance. When plants cannot effectively regulate auxins, they may not grow well, adapt to changing conditions, or produce as much food. Existing IAA detection methods, such as liquid chromatography, require taking plant samples from the plant — which harms or removes part of it. Conventional methods also measure the effects of IAA rather than detecting it directly, and cannot be used universally across different plant types. In addition, since IAA are small molecules that cannot be easily tracked in real time, biosensors that contain fluorescent proteins need to be inserted into the plant’s genome to measure auxin, making it emit a fluorescent signal for live imaging.SMART’s newly developed nanosensor enables direct, real-time tracking of auxin levels in living plants with high precision. The sensor uses near infrared imaging to monitor IAA fluctuations non-invasively across tissues like leaves, roots, and cotyledons, and it is capable of bypassing chlorophyll interference to ensure highly reliable readings even in densely pigmented tissues. The technology does not require genetic modification and can be integrated with existing agricultural systems — offering a scalable precision tool to advance both crop optimization and fundamental plant physiology research. By providing real-time, precise measurements of auxin, the sensor empowers farmers with earlier and more accurate insights into plant health. With these insights and comprehensive data, farmers can make smarter, data-driven decisions on irrigation, nutrient delivery, and pruning, tailored to the plant’s actual needs — ultimately improving crop growth, boosting stress resilience, and increasing yields.“We need new technologies to address the problems of food insecurity and climate change worldwide. Auxin is a central growth signal within living plants, and this work gives us a way to tap it to give new information to farmers and researchers,” says Michael Strano, co-lead principal investigator at DiSTAP, Carbon P. Dubbs Professor of Chemical Engineering at MIT, and co-corresponding author of the paper. “The applications are many, including early detection of plant stress, allowing for timely interventions to safeguard crops. For urban and indoor farms, where light, water, and nutrients are already tightly controlled, this sensor can be a valuable tool in fine-tuning growth conditions with even greater precision to optimize yield and sustainability.”The research team documented the nanosensor’s development in a paper titled, “A Near-Infrared Fluorescent Nanosensor for Direct and Real-Time Measurement of Indole-3-Acetic Acid in Plants,” published in the journal ACS Nano. The sensor comprises single-walled carbon nanotubes wrapped in a specially designed polymer, which enables it to detect IAA through changes in near infrared fluorescence intensity. Successfully tested across multiple species, including Arabidopsis, Nicotiana benthamiana, choy sum, and spinach, the nanosensor can map IAA responses under various environmental conditions such as shade, low light, and heat stress. “This sensor builds on DiSTAP’s ongoing work in nanotechnology and the CoPhMoRe technique, which has already been used to develop other sensors that can detect important plant compounds such as gibberellins and hydrogen peroxide. By adapting this approach for IAA, we’re adding to our inventory of novel, precise, and nondestructive tools for monitoring plant health. Eventually, these sensors can be multiplexed, or combined, to monitor a spectrum of plant growth markers for more complete insights into plant physiology,” says Duc Thinh Khong, research scientist at DiSTAP and co-first author of the paper.“This small but mighty nanosensor tackles a long-standing challenge in agriculture: the need for a universal, real-time, and noninvasive tool to monitor plant health across various species. Our collaborative achievement not only empowers researchers and farmers to optimize growth conditions and improve crop yield and resilience, but also advances our scientific understanding of hormone pathways and plant-environment interactions,” says In-Cheol Jang, senior principal investigator at TLL, principal investigator at DiSTAP, and co-corresponding author of the paper.Looking ahead, the research team is looking to combine multiple sensing platforms to simultaneously detect IAA and its related metabolites to create a comprehensive hormone signaling profile, offering deeper insights into plant stress responses and enhancing precision agriculture. They are also working on using microneedles for highly localized, tissue-specific sensing, and collaborating with industrial urban farming partners to translate the technology into practical, field-ready solutions. The research was carried out by SMART, and supported by the National Research Foundation of Singapore under its Campus for Research Excellence And Technological Enterprise program. More

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      Guardian Ag’s crop-spraying drone is replacing dangerous pilot missions

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      Every year during the growing season, thousands of pilots across the country climb into small planes loaded with hundreds of pounds of pesticides and fly extremely close to the ground at upward of 140 miles an hour, unloading their cargo onto rows of corn, cotton, and soybeans.The world of agricultural aviation is as dangerous as it is vital to America’s farms. Unfortunately, fatal crashes are common. Now Guardian Ag, founded by former MIT Electronics Research Society (MITERS) makers Adam Bercu and Charles Guan ’11, is offering an alternative in the form of a large, purpose-built drone that can autonomously deliver 200-pound payloads across farms. The company’s drones feature an 18-foot spray radius, 80-inch rotors, a custom battery pack, and aerospace-grade materials designed to make crop spraying more safe, efficient, and inexpensive for farmers.“We’re trying to bring technology to American farms that are hundreds or thousands of acres, where you’re not replacing a human with a hand pump — you’re replacing a John Deere tractor or a helicopter or an airplane,” Bercu says.“With Guardian, the operator shows up about 30 minutes before they want to spray, they mix the product, path plan the field in our app, and it gives an estimate for how long the job will take,” he says. “With our fast charging, you recharge the aircraft while you fill the tank, and those two operations take about the same amount of time.”

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      From Battlebots to farmlandsAt a young age, Bercu became obsessed with building robots. Growing up in south Florida, he’d attend robotic competitions, build prototypes, and even dumpster dive for particularly hard-to-find components. At one competition, Bercu met Charles Guan, who would go on to major in mechanical engineering at MIT, and the two robot enthusiasts became lifelong friends.“When Charles came to MIT, he basically convinced me to move to Cambridge,” Bercu says. “He said, ‘You need to come up here. I found more people like us. Hackers!’”Bercu visited Cambridge, Massachusetts, and indeed fell in love with the region’s makerspaces and hacker culture. He moved soon after, and he and Guan began spending free time at spaces including the Artisans Asylum makerspace in Somerville, Massachusetts; MIT’s International Design Center; and the MIT Electronics Research Society (MITERS) makerspace. Guan held several leadership positions at MITERS, including facilities manager, treasurer, and president.“MIT offered enormous latitude to its students to be independent and creative, which was reflected in the degree of autonomy they permit student-run organizations like MITERS to have compared to other top-tier schools,” Guan says. “It was a key selling point to me when I was touring mechanical engineering labs as a junior in high school. I was well-known in the department circle for being at MITERS all the time, possibly even more than I spent on classes.”After Guan graduated, he and Bercu started a hardware consulting business and competed in the robot combat show Battlebots. Guan also began working as a design instructor in MIT’s Department of Mechanical Engineering, where he taught a section of Course 2.007 that tasked students with building go-karts.Eventually, Guan and Bercu decided to use their experience to start a drone company.“Over the course of Battlebots and building go-karts, we knew electric batteries were getting really cheap and electric vehicle supply chains were established,” Bercu explains. “People were raising money to build eVTOL [electric vertical take-off and landing] vehicles to transport people, but we knew diesel fuel still outperformed batteries over long distances. Where electric systems did outperform combustion engines was in areas where you needed peak power for short periods of time. Basically, batteries are awesome when you have a short mission.”That idea made the founders think crop spraying could be a good early application. Bercu’s family runs an aviation business, and he knew pilots who would spray crops as their second jobs.“It’s one of those high-paying but very dangerous jobs,” Bercu says. “Even in the U.S., we lose between 1 and 2 percent of all agriculture pilots each year to fatal accidents. These people are rolling the dice every time they do this: You’re flying 6 feet off the ground at 140 miles an hour with 800 gallons of pesticide in your tank.”After cobbling together spare parts from Battlebots and their consulting business, the founders built a 600-pound drone. When they finally got it to fly, they decided the time was right to launch their company, receiving crucial early guidance and their first funding from the MIT-affiliated investment firm the E14 Fund.The founders spent the next year interviewing crop dusters and farmers. They also started engaging with the Federal Aviation Administration.“There was no category for anything like this,” Bercu explains. “With the FAA, we not only got through the approval process, we helped them build the process as we went through it, because we wanted to establish some common-sense standards.”Guardian custom-built its batteries to optimize throughput and utilization rate of its drones. Depending on the farm, Bercu says his machines can unload about 1.5 to 2 tons of payload per hour.Guardian’s drones can also spray more precisely than planes, reducing the environmental impact of pesticides, which often pollute the landscapes and waterways surrounding farms.“This thing has the precision to spray the ‘Mona Lisa’ on 20 acres, but we’re not leveraging that functionality today,” Bercu says. “For the operator we want to make it very easy. The goal is to take someone who sprays with a tractor and teach them to spray with a drone in less than a week.”Scaling for farmersTo date, Guardian Ag has built eight of its aircraft, which are actively delivering payloads over California farms in trials with paying customers. The company is currently ramping up manufacturing in its 60,000-square-foot facility in Massachusetts, and Bercu says Guardian has a backlog of hundreds of millions of dollars-worth of drones.“Grower demand has been exceptional,” Bercu says. “We don’t need to educate them on the need for this. They see the big drone with the big tank and they’re in.”Bercu envisions Guardian’s drones helping with a number of other tasks like ship-to-ship logistics, delivering supplies to offshore oil rigs, mining, and other areas where helicopters and small aircraft are currently flown through difficult terrain. But for now, the company is focused on starting with agriculture.“Agriculture is such an important and foundational aspect of our country,” says Guardian Ag chief operating officer Ashley Ferguson MBA ’19. “We work with multigenerational farming families, and when we talk to them, it’s clear aerial spray has taken hold in the industry. But there’s a large shortage of pilots, especially for agriculture applications. So, it’s clear there’s a big opportunity.”Seven years since founding Guardian, Bercu remains grateful that MIT’s community opened its doors for him when he moved to Cambridge.“Without the MIT community, this company wouldn’t be possible,” Bercu says. “I was never able to go to college, but I’d love to one day apply to MIT and do my engineering undergrad or go to the Sloan School of Management. I’ll never forget MIT’s openness to me. It’s a place I hold near and dear to my heart.” More

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      in Environment

      Study helps pinpoint areas where microplastics will accumulate

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      The accumulation of microplastics in the environment, and within our bodies, is an increasingly worrisome issue. But predicting where these ubiquitous particles will accumulate, and therefore where remediation efforts should be focused, has been difficult because of the many factors that contribute to their dispersal and deposition.New research from MIT shows that one key factor in determining where microparticles are likely to build up has to do with the presence of biofilms. These thin, sticky biopolymer layers are shed by microorganisms and can accumulate on surfaces, including along sandy riverbeds or seashores. The study found that, all other conditions being equal, microparticles are less likely to accumulate in sediment infused with biofilms, because if they land there, they are more likely to be resuspended by flowing water and carried away.The open-access findings appear in the journal Geophysical Research Letters, in a paper by MIT postdoc Hyoungchul Park and professor of civil and environmental engineering Heidi Nepf. “Microplastics are definitely in the news a lot,” Nepf says, “and we don’t fully understand where the hotspots of accumulation are likely to be. This work gives a little bit of guidance” on some of the factors that can cause these particles, and small particles in general, to accumulate in certain locations.Most experiments looking at the ways microparticles are transported and deposited have been conducted over bare sand, Park says. “But in nature, there are a lot of microorganisms, such as bacteria, fungi, and algae, and when they adhere to the stream bed they generate some sticky things.” These substances are known as extracellular polymeric substances, or EPS, and they “can significantly affect the channel bed characteristics,” he says. The new research focused on determining exactly how these substances affected the transport of microparticles, including microplastics.The research involved a flow tank with a bottom lined with fine sand, and sometimes with vertical plastic tubes simulating the presence of mangrove roots. In some experiments the bed consisted of pure sand, and in others the sand was mixed with a biological material to simulate the natural biofilms found in many riverbed and seashore environments.Water mixed with tiny plastic particles was pumped through the tank for three hours, and then the bed surface was photographed under ultraviolet light that caused the plastic particles to fluoresce, allowing a quantitative measurement of their concentration.The results revealed two different phenomena that affected how much of the plastic accumulated on the different surfaces. Immediately around the rods that stood in for above-ground roots, turbulence prevented particle deposition. In addition, as the amount of simulated biofilms in the sediment bed increased, the accumulation of particles also decreased.Nepf and Park concluded that the biofilms filled up the spaces between the sand grains, leaving less room for the microparticles to fit in. The particles were more exposed because they penetrated less deeply in between the sand grains, and as a result they were much more easily resuspended and carried away by the flowing water.“These biological films fill the pore spaces between the sediment grains,” Park explains, “and that makes the deposited particles — the particles that land on the bed — more exposed to the forces generated by the flow, which makes it easier for them to be resuspended. What we found was that in a channel with the same flow conditions and the same vegetation and the same sand bed, if one is without EPS and one is with EPS, then the one without EPS has a much higher deposition rate than the one with EPS.”Nepf adds: “The biofilm is blocking the plastics from accumulating in the bed because they can’t go deep into the bed. They just stay right on the surface, and then they get picked up and moved elsewhere. So, if I spilled a large amount of microplastic in two rivers, and one had a sandy or gravel bottom, and one was muddier with more biofilm, I would expect more of the microplastics to be retained in the sandy or gravelly river.”All of this is complicated by other factors, such as the turbulence of the water or the roughness of the bottom surface, she says. But it provides a “nice lens” to provide some suggestions for people who are trying to study the impacts of microplastics in the field. “They’re trying to determine what kinds of habitats these plastics are in, and this gives a framework for how you might categorize those habitats,” she says. “It gives guidance to where you should go to find more plastics versus less.”As an example, Park suggests, in mangrove ecosystems, microplastics may preferentially accumulate in the outer edges, which tend to be sandy, while the interior zones have sediment with more biofilm. Thus, this work suggests “the sandy outer regions may be potential hotspots for microplastic accumulation,” he says, and can make this a priority zone for monitoring and protection.“This is a highly relevant finding,” says Isabella Schalko, a research scientist at ETH Zurich, who was not associated with this research. “It suggests that restoration measures such as re-vegetation or promoting biofilm growth could help mitigate microplastic accumulation in aquatic systems. It highlights the powerful role of biological and physical features in shaping particle transport processes.”The work was supported by Shell International Exploration and Production through the MIT Energy Initiative. More

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      Startup helps farmers grow plant-based feed and fertilizer using wastewater

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      Farmers today face a number of challenges, from supply chain stability to nutrient and waste management. But hanging over everything is the need to maintain profitability amid changing markets and increased uncertainty.Fyto, founded by former MIT staff member Jason Prapas, is offering a highly automated cultivation system to address several of farmers’ biggest problems at once.At the heart of Fyto’s system is Lemna, a genus of small aquatic plants otherwise known as duckweed. Most people have probably seen thick green mats of Lemna lying on top of ponds and swamps. But Lemna is also rich in protein and capable of doubling in biomass every two days. Fyto has built an automated cropping system that uses nitrogen-rich wastewater from dairy farms to grow Lemna in shallow pools on otherwise less productive farmland. On top of the pools, the company has built what it believes are the largest agricultural robots in the world, which monitor plant health and harvest the Lemna sustainably. The Lemna can then be used on farms as a high-protein cattle feed or fertilizer supplement.Fyto’s systems are designed to rely on minimal land, water, and labor while creating a more sustainable, profitable food system.“We developed from scratch a robotic system that takes the guesswork out of farming this crop,” says Prapas, who previously led the translational research program of MIT’s Tata Center. “It looks at the crop on a daily basis, takes inventory to know how many plants there are, how much should be harvested to have healthy growth the next day, can detect if the color is slightly off or there are nutrient deficiencies, and can suggest different interventions based on all that data.”From kiddie pools to cow farmsPrapas’ first job out of college was with an MIT spinout called Green Fuel that harvested algae to make biofuel. He went back to school for a master’s and then a PhD in mechanical engineering, but he continued working with startups. Following his PhD at Colorado State University, he co-founded Factor[e] Ventures to fund and incubate startups focused on improving energy access in emerging markets.Through that work, Prapas was introduced to MIT’s Tata Center for Technology and Design.“We were really interested in the new technologies being developed at the MIT Tata Center, and in funding new startups taking on some of these global climate challenges in emerging markets,” Prapas recalls. “The Tata Center was interested in making sure these technologies get put into practice rather than patented and put on a shelf somewhere. It was a good synergy.”One of the people Prapas got to know was Rob Stoner, the founding director of the Tata Center, who encouraged Prapas to get more directly involved with commercializing new technologies. In 2017, Prapas joined the Tata Center as the translational research director. During that time, Prapas worked with MIT students, faculty, and staff to test their inventions in the real world. Much of that work involved innovations in agriculture.“Farming is a fact of life for a lot of folks around the world — both subsistence farming but also producing food for the community and beyond,” Prapas says. “That has huge implications for water usage, electricity consumption, labor. For years, I’d been thinking about how we make farming a more attractive endeavor for people: How do we make it less back-breaking, more efficient, and more economical?”Between his work at MIT and Factor[e], Prapas visited hundreds of farms around the world, where he started to think about the lack of good choices for farming inputs like animal feed and fertilizers. The problem represented a business opportunity.Fyto began with kiddie pools. Prapas started growing aquatic plants in his backyard, using them as a fertilizer source for vegetables. The experience taught him how difficult it would be to train people to grow and harvest Lemna at large scales on farms.“I realized we’d have to invent both the farming method — the agronomy — and the equipment and processes to grow it at scale cost effectively,” Prapas explains.Prapas started discussing his ideas with others around 2019.“The MIT and Boston ecosystems are great for pitching somewhat crazy ideas to willing audiences and seeing what sticks,” Prapas says. “There’s an intangible benefit of being at MIT, where you just can’t help but think of bold ideas and try putting them into practice.”Prapas, who left MIT to lead Fyto in 2019, partnered with Valerie Peng ’17, SM ’19, then a graduate student at MIT who became his first hire.“Farmers work so hard, and I have so much respect for what they do,” says Peng, who serves as Fyto’s head of engineering. “People talk about the political divide, but there’s a lot of alignment around using less, doing more with what you have, and making our food systems more resilient to drought, supply chain disruptions, and everything else. There’s more in common with everyone than you’d expect.”A new farming methodLemna can produce much more protein per acre than soy, another common source of protein on farms, but it requires a lot of nitrogen to grow. Fortunately, many types of farmers, especially large dairy farmers, have abundant nitrogen sources in the waste streams that come from washing out cow manure.“These waste streams are a big problem: In California it’s believed to be one of the largest source of greenhouse gas emissions in the agriculture sector despite the fact that hundreds of crops are grown in California,” Prapas says.For the last few years, Fyto has run its systems in pilots on farms, trialing the crop as feed and fertilizer before delivering to its customers. The systems Fyto has deployed so far are about 50 feet wide, but it is actively commissioning its newest version that’s 160 feet wide. Eventually, Fyto plans to sell the systems directly to farmers.Fyto is currently awaiting California’s approval for use in feed, but Lemna has already been approved in Europe. Fyto has also been granted a fertilizer license on its plant-based fertilizer, with promising early results in trials, and plans to sell new fertilizer products this year.Although Fyto is focused on dairy farms for its early deployments, it has also grown Lemna using manure from chicken, and Prapas notes that even people like cheese producers have a nitrogen waste problem that Fyto could solve.“Think of us like a polishing step you could put on the end of any system that has an organic waste stream,” Prapas says. “In that situation, we’re interested in growing our crops on it. We’ve had very few things that the plant can’t grow on. Globally, we see this as a new farming method, and that means it’s got a lot of potential applications.” More

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      in Environment

      For plants, urban heat islands don’t mimic global warming

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      It’s tricky to predict precisely what the impacts of climate change will be, given the many variables involved. To predict the impacts of a warmer world on plant life, some researchers look at urban “heat islands,” where, because of the effects of urban structures, temperatures consistently run a few degrees higher than those of the surrounding rural areas. This enables side-by-side comparisons of plant responses.But a new study by researchers at MIT and Harvard University has found that, at least for forests, urban heat islands are a poor proxy for global warming, and this may have led researchers to underestimate the impacts of warming in some cases. The discrepancy, they found, has a lot to do with the limited genetic diversity of urban tree species.The findings appear in the journal PNAS, in a paper by MIT postdoc Meghan Blumstein, professor of civil and environmental engineering David Des Marais, and four others.“The appeal of these urban temperature gradients is, well, it’s already there,” says Des Marais. “We can’t look into the future, so why don’t we look across space, comparing rural and urban areas?” Because such data is easily obtainable, methods comparing the growth of plants in cities with similar plants outside them have been widely used, he says, and have been quite useful. Researchers did recognize some shortcomings to this approach, including significant differences in availability of some nutrients such as nitrogen. Still, “a lot of ecologists recognized that they weren’t perfect, but it was what we had,” he says.Most of the research by Des Marais’ group is lab-based, under conditions tightly controlled for temperature, humidity, and carbon dioxide concentration. While there are a handful of experimental sites where conditions are modified out in the field, for example using heaters around one or a few trees, “those are super small-scale,” he says. “When you’re looking at these longer-term trends that are occurring over space that’s quite a bit larger than you could reasonably manipulate, an important question is, how do you control the variables?”Temperature gradients have offered one approach to this problem, but Des Marais and his students have also been focusing on the genetics of the tree species involved, comparing those sampled in cities to the same species sampled in a natural forest nearby. And it turned out there were differences, even between trees that appeared similar.“So, lo and behold, you think you’re only letting one variable change in your model, which is the temperature difference from an urban to a rural setting,” he says, “but in fact, it looks like there was also a genotypic diversity that was not being accounted for.”The genetic differences meant that the plants being studied were not representative of those in the natural environment, and the researchers found that the difference was actually masking the impact of warming. The urban trees, they found, were less affected than their natural counterparts in terms of when the plants’ leaves grew and unfurled, or “leafed out,” in the spring.The project began during the pandemic lockdown, when Blumstein was a graduate student. She had a grant to study red oak genotypes across New England, but was unable to travel because of lockdowns. So, she concentrated on trees that were within reach in Cambridge, Massachusetts. She then collaborated with people doing research at the Harvard Forest, a research forest in rural central Massachusetts. They collected three years of data from both locations, including the temperature profiles, the leafing-out timing, and the genetic profiles of the trees. Though the study was looking at red oaks specifically, the researchers say the findings are likely to apply to trees broadly.At the time, researchers had just sequenced the oak tree genome, and that allowed Blumstein and her colleagues to look for subtle differences among the red oaks in the two locations. The differences they found showed that the urban trees were more resistant to the effects of warmer temperatures than were those in the natural environment.“Initially, we saw these results and we were sort of like, oh, this is a bad thing,” Des Marais says. “Ecologists are getting this heat island effect wrong, which is true.” Fortunately, this can be easily corrected by factoring in genomic data. “It’s not that much more work, because sequencing genomes is so cheap and so straightforward. Now, if someone wants to look at an urban-rural gradient and make these kinds of predictions, well, that’s fine. You just have to add some information about the genomes.”It’s not surprising that this genetic variation exists, he says, since growers have learned by trial and error over the decades which varieties of trees tend to thrive in the difficult urban environment, with typically poor soil, poor drainage, and pollution. “As a result, there’s just not much genetic diversity in our trees within cities.”The implications could be significant, Des Marais says. When the Intergovernmental Panel on Climate Change (IPCC) releases its regular reports on the status of the climate, “one of the tools the IPCC has to predict future responses to climate change with respect to temperature are these urban-to-rural gradients.” He hopes that these new findings will be incorporated into their next report, which is just being drafted. “If these results are generally true beyond red oaks, this suggests that the urban heat island approach to studying plant response to temperature is underpredicting how strong that response is.”The research team included Sophie Webster, Robin Hopkins, and David Basler from Harvard University and Jie Yun from MIT. The work was supported by the National Science Foundation, the Bullard Fellowship at the Harvard Forest, and MIT. More

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      in Environment

      3 Questions: Exploring the limits of carbon sequestration

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      As part of a multi-pronged approach toward curbing the effects of greenhouse gas emissions, scientists seek to better understand the impact of rising carbon dioxide (CO2) levels on terrestrial ecosystems, particularly tropical forests. To that end, climate scientist César Terrer, the Class of 1958 Career Development Assistant Professor of Civil and Environmental Engineering (CEE) at MIT, and colleague Josh Fisher of Chapman University are bringing their scientific minds to bear on a unique setting — an active volcano in Costa Rica — as a way to study carbon dioxide emissions and their influence. Elevated CO2 levels can lead to a phenomenon known as the CO2 fertilization effect, where plants grow more and absorb greater amounts of carbon, providing a cooling effect. While this effect has the potential to be a natural climate change mitigator, the extent of how much carbon plants can continue to absorb remains uncertain. There are growing concerns from scientists that plants may eventually reach a saturation point, losing their ability to offset increasing atmospheric CO2. Understanding these dynamics is crucial for accurate climate predictions and developing strategies to manage carbon sequestration. Here, Terrer discusses his innovative approach, his motivations for joining the project, and the importance of advancing this research.Q: Why did you get involved in this line of research, and what makes it unique?A: Josh Fisher, a climate scientist and long-time collaborator, had the brilliant idea to take advantage of naturally high CO2 levels near active volcanoes to study the fertilization effect in real-world conditions. Conducting such research in dense tropical forests like the Amazon — where the largest uncertainties about CO2 fertilization exist — is challenging. It would require large-scale CO2 tanks and extensive infrastructure to evenly distribute the gas throughout the towering trees and intricate canopy layers — a task that is not only logistically complex, but also highly costly. Our approach allows us to circumvent those obstacles and gather critical data in a way that hasn’t been done before.Josh was looking for an expert in the field of carbon ecology to co-lead and advance this research with him. My expertise of understanding the dynamics that regulate carbon storage in terrestrial ecosystems within the context of climate change made for a natural fit to co-lead and advance this research with him. This field has been central to my research, and was the focus of my PhD thesis.Our experiments inside the Rincon de la Vieja National Park are particularly exciting because CO2 concentrations in the areas near the volcano are four times higher than the global average. This gives us a rare opportunity to observe how elevated CO2 affects plant biomass in a natural setting — something that has never been attempted at this scale.Q: How are you measuring CO2 concentrations at the volcano?A: We have installed a network of 50 sensors in the forest canopy surrounding the volcano. These sensors continuously monitor CO2 levels, allowing us to compare areas with naturally high CO2 emissions from the volcano to control areas with typical atmospheric CO2 concentrations. The sensors are Bluetooth-enabled, requiring us to be in close proximity to retrieve the data. They will remain in place for a full year, capturing a continuous dataset on CO2 fluctuations. Our next data collection trip is scheduled for March, with another planned a year after the initial deployment.Q: What are the long-term goals of this research?A: Our primary objective is to determine whether the CO2 fertilization effect can be sustained, or if plants will eventually reach a saturation point, limiting their ability to absorb additional carbon. Understanding this threshold is crucial for improving climate models and carbon mitigation strategies.To expand the scope of our measurements, we are exploring the use of airborne technologies — such as drones or airplane-mounted sensors — to assess carbon storage across larger areas. This would provide a more comprehensive view of carbon sequestration potential in tropical ecosystems. Ultimately, this research could offer critical insights into the future role of forests in mitigating climate change, helping scientists and policymakers develop more accurate carbon budgets and climate projections. If successful, our approach could pave the way for similar studies in other ecosystems, deepening our understanding of how nature responds to rising CO2 levels. More