Engineering plants for a changing climate

Special issue of PLOS Biology explores plant engineering as a tool to improve the climate resilience and carbon capture potential of crops

Peer-Reviewed Publication

PLOS

 

IMAGE: CROPS GROWING IN DRY GROUND. AS THE CLIMATE CHANGES, CROP CULTIVATION BECOMES MORE CHALLENGING. THIS COLLECTION OF ARTICLES EXPLORES STRATEGIES TO HELP PLANTS ADAPT TO A CHANGING CLIMATE. view more 

CREDIT: JOANNA CLARKE (CC-BY 4.0, HTTPS://CREATIVECOMMONS.ORG/LICENSES/BY/4.0/)

Climate change is affecting the types of plant varieties we can cultivate, as well as how and where we can do so. A new collection of articles in the open access journal PLOS Biology explores the twin challenges of engineering plants for resilience to climate change and enhancing their carbon-capture potential. PLOS Biology Editors Pamela Ronald & Joanna Clarke provide a summary editorial, and details regarding the other papers may be found below.

To meet the agricultural challenges caused by climate change and a growing population, we need to improve crop production. This Perspective from industry leaders including Catherine Feuillet calls for more and better public–private partnerships to accelerate discoveries in crop research.

How can we sustainably feed our growing population as the climate changes? This Perspective from Megan Matthews argues that by engineering photosynthesis to increase carbon capture, we can mitigate climate change and increase food production.

As climate change affects weather patterns and soil health, agricultural productivity could decrease substantially. Synthetic biology can be used to enhance climate-resilience in plants and create the next generation of crops, if the public will accept it, according to this article from Jennifer Brophy.

The microbiome of cropland soils could be manipulated to accelerate soil carbon sequestration. This Perspective from Noah Fierer suggests how this could be achieved and outlines the general steps required to develop, implement, and validate such microbial-based strategies.

Of all crop species, rice has the most genetic potential for adaptation to climate change, and Genebank accessions have been critical in developing improved stress-tolerant rice varieties. This Community Page from Kenneth McNally highlights new tools and resources from the International Rice Research Institute for accelerating the identification and deployment of genes conferring climate-change resilience.

Our basic understanding of carbon cycling in the biosphere remains qualitative and incomplete, precluding our ability to effectively engineer novel solutions to climate change. How can we attempt to engineer the unknown? This Essay from Patrick Shih proposes that the main contributions of plant synthetic biology in addressing climate change will lie not in delivering desired genotypes but in enabling the predictive understanding necessary to design target genotypes in the first place.

Cultivated species have reduced genetic diversity relative to their closest wild relatives. Preserving the rich genetic resources that crop wild relatives offer while avoiding detrimental variants and maladaptive genetic contributions is a central challenge for ongoing crop improvement. This Essay from Jeffrey Ross-Ibarra supports the use of traditional varieties as an intermediate between wild relatives and modern cultivars to increase genetic diversity in crops.

As the climate changes, so too will the relationship between humans and the plants we use for food, medicine, shelter, fuel and clothing. What, how and where we cultivate plants will change, as will the potential biotic and abiotic stresses faced by cultivated plants. This collection of articles explores strategies to help plants adapt to a changing climate, including ancient and modern breeding techniques, genome engineering, synthetic biology and microbiome engineering. 

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The full Collection is available in PLOS Biology here: https://collections.plos.org/collection/engineering-plants-for-a-changing-climate/

In your coverage, please use these URLs to provide access to the freely available papers in PLOS Biology:

https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3002243

https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3002181

https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3002183

https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3002208

https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3002207

https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3002215

https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3002190

https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3002235

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JOURNAL

PLoS Biology

DOI

10.1371/journal.pbio.3002243 

METHOD OF RESEARCH

Commentary/editorial

Billions of nanoplastics released when microwaving baby food containers

Exposure to plastic particles kills up to 75% of cultured kidney cells

Peer-Reviewed Publication

UNIVERSITY OF NEBRASKA-LINCOLN

 

IMAGE: KAZI ALBAB HUSSAIN (LEFT) HOLDS HIS SON WHILE REMOVING A PLASTIC CONTAINER OF WATER FROM A MICROWAVE. HUSSAIN AND COLLEAGUES AT THE UNIVERSITY OF NEBRASKA–LINCOLN HAVE FOUND THAT MICROWAVING SUCH CONTAINERS CAN RELEASE UP TO BILLIONS OF NANOSCOPIC PARTICLES AND MILLIONS OF MICROSCOPIC ONES. view more 

CREDIT: CRAIG CHANDLER, UNIVERSITY OF NEBRASKA–LINCOLN

The fastest way to heat food and drink might also rank as the fastest route to ingesting massive quantities of minuscule plastic particles, says new research from the University of Nebraska–Lincoln.

Experiments have shown that microwaving plastic baby food containers available on the shelves of U.S. stores can release huge numbers of plastic particles — in some cases, more than 2 billion nanoplastics and 4 million microplastics for every square centimeter of container.

Though the health effects of consuming micro- and nanoplastics remain unclear, the Nebraska team further found that three-quarters of cultured embryonic kidney cells had died after two days of being introduced to those same particles. A 2022 report from the World Health Organization recommended limiting exposure to such particles.

“It is really important to know how many micro- and nanoplastics we are taking in,” said Kazi Albab Hussain, the study’s lead author and a doctoral student in civil and environmental engineering at the University of Nebraska–Lincoln. “When we eat specific foods, we are generally informed or have an idea about their caloric content, sugar levels, other nutrients. I believe it’s equally important that we are aware of the number of plastic particles present in our food.

“Just as we understand the impact of calories and nutrients on our health, knowing the extent of plastic particle ingestion is crucial in understanding the potential harm they may cause. Many studies, including ours, are demonstrating that the toxicity of micro- and nanoplastics is highly linked to the level of exposure.”

The team embarked on its study in 2021, the same year that Hussain became a father. While prior research had investigated the release of plastic particles from baby bottles, the team realized that no studies had examined the sorts of plastic containers and pouches that Hussain found himself shopping for, and that millions of other parents regularly do, too.

Hussain and his colleagues decided to conduct experiments with two baby food containers made from polypropylene and a reusable pouch made of polyethylene, both plastics approved by the U.S. Food and Drug Administration. In one experiment, the researchers filled the containers with either deionized water or 3% acetic acid — the latter intended to simulate dairy products, fruits, vegetables and other relatively acidic consumables — then heated them at full power for three minutes in a 1,000-watt microwave. Afterward, they analyzed the liquids for evidence of micro- and nanoplastics: the micro being particles at least 1/1,000th of a millimeter in diameter, the nano any particles smaller.

The actual number of each particle released by the microwaving depended on multiple factors, including the plastic container and the liquid within it. But based on a model that factored in particle release, body weight, and per-capita ingestion of various food and drink, the team estimated that infants drinking products with microwaved water and toddlers consuming microwaved dairy products are taking in the greatest relative concentrations of plastic. Experiments designed to simulate the refrigeration and room-temperature storage of food or drink over a six-month span also suggested that both could lead to the release of micro- and nanoplastics.

“For my baby, I was unable to completely avoid the use of plastic,” Hussain said. “But I was able to avoid those (scenarios) which were causing more of the release of micro- and nanoplastics. People also deserve to know those, and they should choose wisely.”

With the help of Svetlana Romanova from the University of Nebraska Medical Center, the team then cultured and exposed embryonic kidney cells to the actual plastic particles released from the containers — a first, as far as Hussain can tell. Rather than introduce just the number of particles released by one container, the researchers instead exposed the cells to particle concentrations that infants and toddlers might accumulate over days or from multiple sources.

After two days, just 23% of kidney cells exposed to the highest concentrations had managed to survive — a much higher mortality rate than that observed in earlier studies of micro- and nanoplastic toxicity. The team suspects that kidney cells might be more susceptible to the particles than are other cell types examined in prior research. But those earlier studies also tended to examine the effects of larger polypropylene particles, some of them potentially too large to penetrate cells. If so, the Hussain-led study could prove especially sobering: Regardless of its experimental conditions, the Husker team found that polypropylene containers and polyethylene pouches generally release about 1,000 times more nanoplastics than microplastics.

The question of cell infiltration is just one among many that will require answers, Hussain said, before determining the true risks of consuming micro- and nanoplastics. But to the extent that they do pose a health threat — and that plastics remain a go-to for baby food storage — parents would have a vested interest in seeing that the companies manufacturing plastic containers seek out viable alternatives, he said.

“We need to find the polymers which release fewer (particles),” Hussain said. “Probably, researchers will be able to develop plastics that do not release any micro- or nanoplastics — or, if they do, the release would be negligible.

“I am hopeful that a day will come when these products display labels that read ‘microplastics-free’ or ‘nanoplastics-free.’”

The team reported its findings in the journal Environmental Science & Technology. Hussain and Romanova authored the study with the University of Nebraska–Lincoln’s Yusong Li, Mathias Schubert, Yongfeng Lu, Lucía Fernández-Ballester, Bing Wang, Xi Huang, Jesse Kuebler, Dong Zhang and Ilhami Okur. The researchers received support from the National Science Foundation and the Buffett Early Childhood Institute.

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JOURNAL

Environmental Science & Technology

DOI

10.1021/acs.est.3c01942 

Paleontologists identify two new species of sabertooth cat

Peer-Reviewed Publication

CELL PRESS

 

IMAGE: GRAPHICAL ABSTRACT view more 

CREDIT: ISCIENCE JIANGZUO ET AL.

Sabertooth cats make up a diverse group of long-toothed predators that roamed Africa around 6-7 million years ago, around the time that hominins—the group that includes modern humans—began to evolve. By examining one of the largest global Pliocene collections of fossils in Langebaanweg, north of Cape Town in South Africa, researchers present two new sabertooth species and the first family tree of the region’s ancient sabertooths on July 20 in the journal iScience. Their results suggest that the distribution of sabertooths throughout ancient Africa might have been different than previously assumed, and the study provides important information about Africa’s paleoenvironment.

“The known material of sabertooths from Langebaanweg was relatively poor, and the importance of these sabertoothed cats has not been properly recognized,” says senior author Alberto Valenciano (@paleo_alberto), a paleontologist at Complutense University. “Our phylogenetic analysis is the first one to take Langebaanweg species into consideration.”

The study described a total of four species. Two of these species, Dinofelis werdelini and Lokotunjailurus chimsamyae, were previously unknown. Dinofelis sabertooths are globally distributed, and their fossils have been found in Africa, China, Europe, and North America. The researchers were expecting to identify a new Dinofelis species from Langebaanweg based on prior research. However, Lokotunjailurus has only ever been identified in Kenya and Chad before this analysis. This suggests that they may have been distributed all throughout Africa between 5–7 million years ago.

Valenciano was a postdoctoral fellow at the Iziko Museums of South Africa, which houses all the sabertooth fossils that were analyzed in this study. A team of colleagues from China, South Africa, and Spain put the final project together. To construct a family tree, the researchers classified the physical traits of each sabertooth species—such as presence or absence of teeth, jaw and skull shape, and tooth structure—and coded this information into a matrix that could determine how closely related each sabertooth was to its evolutionary cousins.

The resulting population composition of Langebaanweg sabertooths (Machairodontini, Metailurini, and Feline) reflects the increasing global temperatures and environmental changes of the Pliocene epoch. For instance, the presence of Machairodontini cats, which are larger in size and more adapted to running at high speeds, suggests that there were open grassland environments at Langebaanweg. However, the presence of the Metailurini cats suggests that there were also more covered environments, such as forests. While the fact that researchers found both Metailurine and Machairodonti species suggests that Langebaanweg contained a mixture of forest and grassland 5.2 million years ago, the high proportion of Machairodonti species compared with other fossil localities from Eurasia and Africa confirm that southern Africa was transitioning toward more open grasslands during this period.

“The continuous aridification throughout the Mio-Pliocene, with the spread of open environments, could be an important trigger on the bipedalism of hominids,” the authors write. “The sabertooth guild in Langebaanweg and its environmental and paleobiogeographic implications provide background for future discussion on hominid origination and evolution.”

Interestingly, the researchers also note that the composition of sabertooths in Langebaanweg closely mirrors that of Yuanmou, China. Yuanmou’s Longchuansmilus sabertooths might even have a close evolutionary relationship with Africa’s Lokotunjailurus species.

 “This suggests that the ancient environment of the two regions was similar or that there was a potential migration route between the Langebaanweg and Yuanmou,” says first author Qigao Jiangzuo, a paleontologist at Peking University.

More fossil evidence could help paleontologists understand exactly how these two sites are related. “The two new sabertooths are only an example of the numerous unpublished fossils from Langebaanweg housed at Iziko in the Cenozoic Collections,” says Romala Govender, a curator and paleontologist at the Iziko Museums in South Africa. “This brings to the fore the need for new and detailed studies of Langebaanweg fauna.”

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This work was supported by the Spanish Ministry of Science and Innovation, the Chinese Natural Science Foundation Program, the Strategic Priority Research Program of Chinese Academy of Sciences, the NRF, the Government of Aragon, the Generalitat de Catalunya, the Spanish Ministry of Science, Innovation, and Universities, the Research Group UCM, The GENUS, and the Oppenheimer Memorial Trust. The authors declare no competing interests.

iScience, Jiangzuo et al. “Langebaanweg’s sabertooth guild reveals an African Pliocene evolutionary hotspot for sabertooths (Carnivora; Felidae)” https://www.cell.com/iscience/fulltext/S2589-0042(23)01289-0 

iScience (@iScience_CP) is an open-access journal from Cell Press that provides a platform for original research and interdisciplinary thinking in the life, physical, and earth sciences. The primary criterion for publication in iScience is a significant contribution to a relevant field combined with robust results and underlying methodology. Visit: http://www.cell.com/iscience. To receive Cell Press media alerts, contact press@cell.com.  

An array of sabertooth teeth from Dinofelis, Lokotunjailurus, and Adeilosmilus CREDIT iScience Jiangzuo et al.

A sabertooth tiger family tree CREDIT iScience Jiangzuo et al.

CREDIT

iScience Jiangzuo et al.

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JOURNAL

iScience

DOI

10.1016/j.isci.2023.107212 

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Langebaanweg’s sabertooth guild reveals an African Pliocene evolutionary hotspot for sabertooths (Carnivora; Felidae)

ARTICLE PUBLICATION DATE

20-Jul-2023

POPULAR AQUARIUM FISH

Animal behavior: Neon tetra fish form queues to avoid bottlenecks

Peer-Reviewed Publication

SCIENTIFIC REPORTS

Schools of neon tetra fish (Paracheirodon innesi) use queuing to evacuate through narrow spaces without clogging or colliding, according to a study published in Scientific Reports.

Aurélie Dupont and colleagues observed neon tetra evacuate in groups of 30 through a narrow opening in a tank, which ranged in diameter from 1.5 to 4 centimetres, in response to the movements of a fishing net. Neon tetra measure approximately 0.5 centimetres wide and 3 centimetres long.

The authors observed that fish evacuated at faster rates through larger openings than smaller openings, but that fish evacuating through all sizes of opening tended to do so at a constant rate — with the exception of the last few fish in each group, who tended to exit more slowly. Although fish gathered around openings of all sizes prior to passing through them, the authors did not observe physical contact between evacuating fish. Together, the findings indicate that neon tetra may wait or queue before evacuating through narrow openings in order to maintain a preferred social distance and avoid clogging. This is similar to evacuation behaviours observed in previous studies of ants but is in contrast to those observed in herds of sheep and human crowds, where clogging often occurs.

The authors suggest that the behaviours of fish in their study may reflect the behaviours of schools of wild neon tetra passing between rocks in rivers. They propose that their findings could be used to inform the development of swarm robots, as well as traffic management methods for autonomous cars and human crowds.

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Article details

Fish evacuate smoothly respecting a social bubble

DOI: 10.1038/s41598-023-36869-9

Corresponding Author:

Aurélie Dupont
Université Grenoble Alpes, Grenoble, France
Email: aurelie.dupont@univ-grenoble-alpes.fr

Please link to the article in online versions of your report (the URL will go live after the embargo ends): https://www.nature.com/articles/s41598-023-36869-9

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JOURNAL

Scientific Reports

DOI

10.1038/s41598-023-36869-9 

ARTICLE TITLE

Fish evacuate smoothly respecting a social bubble

ARTICLE PUBLICATION DATE

20-Jul-2023

 

Gene variation makes apple trees ‘weep,’ improving orchards

Peer-Reviewed Publication

CORNELL UNIVERSITY

ITHACA, N.Y. -- Plant geneticists have identified a mutation in a gene that causes the “weeping” architecture – branches growing downwards – in apple trees, a finding that could improve orchard fruit production.

For more than a century, growers have tied down apple branches when trees are young, in order to improve crop productivity. More research is needed to understand the mechanism for why branch bending improves yields, but studies have shown that the practice helps apple trees allocate more resources such as carbon and other nutrients toward reproductive growth (flowering and fruiting) than toward vegetative growth (branches and leaves).

In rare cases, trees are known to naturally grow downwards.

The new study, published early release on July 3 in the journal Plant Physiology, identified a variation, or allele, of MdLAZY1A – a gene that largely controls weeping growth in apple.

“The findings presented in this paper could be used to make existing apple cultivars grow somewhat downwards and/or with more spreading branches, so they can be more productive, and it can save on labor costs of tying branches down,” said senior author Kenong Xu, associate professor in the School of Integrative Plant Science Horticulture Section at Cornell AgriTech in the College of Agriculture and Life Sciences.

The mutation is rare, occurring in less than 1% of trees.

Now that the mutation – a single nucleotide substitution to the MdLAZY1A gene – has been identified, plant geneticists might use CRISPR/Cas-9 gene editing technology to develop cultivars with weeping-like growth, Xu said.

“We confirmed it through multiple transgenic studies,” Xu said. “We put that allele in a standard royal gala apple cultivar and the tree grew downward.”

To identify the gene, the researchers used a “forward genetics” approach, where they looked at the observable traits in more than 1,000 offspring of weeping cultivars, and separated those that exhibited weeping vs. normal growth. They then used advanced genetic sequencing techniques to compare the two populations to locate the genetic determinant.

Laura Dougherty, Ph.D. ’19, a former postdoctoral researcher at Cornell and currently a research geneticist at the U.S. Department of Agriculture Agricultural Research Service, is the paper’s first author. Co-authors include Susan Brown, professor in the School of Integrative Plant Science (SIPS) Horticulture Section at Cornell AgriTech, and Miguel Piñeros, adjunct associate professor in SIPS’ Plant Biology Section.

The study was funded by the National Science Foundation Plant Genome Research Program.

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JOURNAL

PLANT PHYSIOLOGY

DOI

10.1093/plphys/kiad373 

21ST CENTURY SPAGYRIC HERBALISM

The power of flowers: New Zealand researchers discover that dahlia flowers have antidiabetic properties by targeting the brain as a key regulator of blood sugar

Peer-Reviewed Publication

HIGHER EDUCATION PRESS

 

IMAGE: THE EXTRACT INHIBITS THE IKKΒ/NF-ΚB PATHWAY AND HAS MARKED ANTI-INFLAMMATORY PROPERTIES. view more 

CREDIT: DOMINIK PRETZ, PHILIP M HEYWARD, JEREMY KREBS, JOEL GRUCHOT, CHARLES BARTER, PAT SILCOCK, NERIDA DOWNES, MOHAMMED ZUBAIR RIZWAN, ALISA BOUCSEIN, JULIA BENDER, ELAINE J BURGESS, GEKE ALINE BOER, PRAMUK KEERTHISINGHE, NIGEL B PERRY, ALEXANDER TUPS

In a clinical trial, University of Otago, Dunedin, New Zealand researchers have discovered a dahlia extract that improves blood sugar regulation without reported side effects in humans. This is a ground-breaking discovery as it for the first time suggests that dysfunctional glucoregulation by the brain can be targeted therapeutically using potent plant molecules to treat type 2 diabetes.

Almost 170 years ago, Claude Bernard, the founder of modern medicine, discovered that the brain plays an important role in the regulation of blood sugar. However, due to the discovery of insulin in 1922, his ground-breaking discovery got almost forgotten until recently. It has been subsequently established that the brain contains a region called the hypothalamus that plays an essential role in the regulation of blood sugar. This region can be damaged through inflammatory processes that are brought about by excess consumption of a Western Style diet enriched in long-chain saturated fatty acids, for example, contained in lard, and this is regarded as a hallmark in the pathogenesis of metabolic diseases like type 2 diabetes. In 2015, Associate Professor Tups and colleagues discovered that butein, a specific plant molecule, could block these inflammatory processes that damage the hypothalamus, and butein potently improved blood sugar regulation in mice.

In the current study, published in Life Metabolism, the New Zealand researchers reported that flowers of the non-toxic dahlia plant are a cultivable source of butein. Intriguingly, in a mouse model of diet-induced metabolic disease, an extract from this plant improved blood sugar regulation. Furthermore, the researchers demonstrate that the effect of butein was enhanced by the presence of two additional plant molecules that were obtained from the flower in a specific extraction process. When the researchers used molecular tools that stopped insulin from working in the brain, the ability of the dahlia extract to improve blood sugar regulation was lost, suggesting that the extract improves the brain’s function required for blood sugar regulation. This was substantiated by the observation that the extract enhanced the function of insulin in the brain and the discovery that the extract acts as a neuro-anti-inflammatory (Figure 1).

Confirming this, a randomized controlled crossover clinical trial on participants with prediabetes or type 2 diabetes revealed that the dahlia extract improved blood sugar regulation without reported side effects in humans.

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Reference: Dominik Pretz et al. (2023) A dahlia flower extract has anti-diabetic properties by improving insulin function in the brain.  Life Metabolism.  https://doi.org/10.1093/lifemeta/load026.

 

About Higher Education Press

Founded in May 1954, Higher Education Press Limited Company (HEP), affiliated with the Ministry of Education, is one of the earliest institutions committed to educational publishing after the establishment of P. R. China in 1949. After striving for six decades, HEP has developed into a major comprehensive publisher, with products in various forms and at different levels. Both for import and export, HEP has been striving to fill in the gap of domestic and foreign markets and meet the demand of global customers by collaborating with more than 200 partners throughout the world and selling products and services in 32 languages globally. Now, HEP ranks among China’s top publishers in terms of copyright export volume and the world’s top 50 largest publishing enterprises in terms of comprehensive strength.

About Life Metabolism

Life Metabolism is a fully open access, peer-reviewed journal that publishes one volume per year online, providing a platform for the publication of works of high significance and broad interest in all areas of metabolism. Life Metabolism welcomes several different article types, including original article, review article, research highlight, letter, editorial, perspective, and so on. Once a paper is accepted, Life Metabolism can publish a precopyedited, preproofed version of the paper online within 48 hours of receiving a signed licence, and this will be replaced by a copyedited, proofed version of the paper as soon as it is ready. The Editors-in-Chief are professors Peng Li at Tsinghua University and John R Speakman at University of Aberdeen, UK. In the first three years, there will be no publication costs for publishing in Life Metabolism, and Open Access fees will be waived.

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JOURNAL

Life Metabolism

DOI

10.1093/lifemeta/load026 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

A dahlia flower extract has anti-diabetic properties by improving insulin function in the brain

 

UvA chemists recycle shrimp waste as catalyst for hydrogen generation

Peer-Reviewed Publication

UNIVERSITEIT VAN AMSTERDAM

Since 2020, the Heterogeneous Catalysis & Sustainable Chemistry group at the UvA’s Van ‘t Hoff Institute for Molecular Sciences has been working on using alkali metal borohydride salts as future hydrogen carriers. These solid salts can be stored safely in air under ambient conditions and release hydrogen gas only when reacting with water. However, controlling the hydrogen release, and thus preventing runaway reactions, is challenging. One solution is to stabilise the solution with a base, and control the hydrogen release by using a catalyst. The UvA team, led by Prof. Gadi Rothenberg, is developing such catalysts in collaboration with the Austrian Competence Centre for Tribology (AC2T) and the company Electriq Global.

Hydrogen destroys catalyst particles

Finding potential catalysts is easy, but getting them to work long enough to be commercially viable is not. The combination of high reaction pH and a continuous release of hydrogen bubbles destroys traditional catalysts within a few days. For instance, the team succeeded in designing highly active and selective cobalt-containing catalyst particles. The high activity, however, results in high volumes of hydrogen that rapidly destroy the particles.

The breakthrough came during a so-called Friday Afternoon experiment when MSc student Jeffrey Jonk and PhD student Fran Pope decided to try and encapsulate cobalt particles in chitosan spheres. Chitosan is a natural polymer that can be produced from chitin, the main component of insect exoskeletons and crustacean shells. It is a biodegradable, biocompatible material that is widely available on multi-ton scale, produced mostly from shrimp and crab shell waste.

The recurring amine groups on the chitosan backbone make it highly soluble in aqueous acidic solutions but sparingly soluble in basic ones. Chitosan spheres can therefore be relatively easy produced by dropping the liquid chitosan into a basic solution. A crucial property of the chitosan spheres is their flexibility which enables them to expand during the generation of hydrogen. They can thus “breathe out” the hydrogen bubbles without breaking. And since they are made at high pH, the basicity of the borohydride solution poses no problem.

Real-life potential for chitosan-based catalysts

The team tested the new catalysts in batch and continuous modes, monitoring the reactions by measuring the flow of hydrogen generated. A few mm-sized spheres loaded with 7% cobalt were sufficient to generate 40 mL hydrogen per minute in a continuous reactor for two days, showing the real-life potential of this new catalyst.

According to Rothenberg the work highlights the importance of catalyst stability as a research focus. “Many papers focus on activity and selectivity, because journals have become focused on publishing spectacular results”, he says. “Yet if you look at the chemical industry, none of these “spectacular” catalysts are used in practice. The reason is that running a successful reaction for a few hours, or even a few days, means nothing for large-scale processes. A real catalyst must work for months and years to be economically viable. We’re not there yet.”

Hydrogen may be energy carrier of the future, but it comes with its own set of challenges. When stored as a compressed gas or in liquid form, molecular hydrogen, H2, is highly energy intensive. This is an advantage in some applications, but a safety concern in others. For medium-scale storage and release on mobile installations, such as cranes, ships and generators, other modes of storing hydrogen are preferable. There are many forms of hydrogen carriers. High hydrogen storage capacity examples include ammonia, methanol, formic acid and others. Yet each has its pros and cons. Methanol has a high capacity (12.5 wt%) but dehydrogenation requires high temperatures and may also emit CO2. Ammonia may contaminate the H2 streams generated, and is a toxic gas itself under ambient conditions. As an alternative, alkali borohydrides can provide a safe source of hydrogen, binding it chemically as a solid salt. A reaction with water releases the hydrogen, and the resulting metaborate salt by-product can be reprocessed and repurposed for hydrogen storage.

 

Original open-access paper:

From shrimp balls to hydrogen bubbles: Borohydride hydrolysis catalysed by flexible cobalt chitosan spheres. F. Pope, J. Jonk, M. Fowler, P.C.M. Laan, N.J. Geels, L. Drangai, V. Gitis and G. Rothenberg, Green Chem., 2023, 25, 5727-5734. DOI: 10.1039/d3gc00821e

See also:

• Research group Heterogeneous Catalysis and Sustainable Chemistry
• Austrian Competence Centre for Tribology
• Electriq Global
• Optimizing hydrogen storage in hydroborate salts

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JOURNAL

Green Chemistry

DOI

10.1039/d3gc00821e 

ARTICLE TITLE

From shrimp balls to hydrogen bubbles: borohydride hydrolysis catalysed by flexible cobalt chitosan spheres

ARTICLE PUBLICATION DATE

19-Jul-2023