Three unexpected foods in alternatives to traditional plastics

Peer-Reviewed Publication

AMERICAN CHEMICAL SOCIETY

 

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THIS TABLE IS MADE FROM A MATERIAL CONTAINING AN UNEXPECTED FOODSTUFF: COFFEE GROUNDS.

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CREDIT: ADAPTED FROM ACS OMEGA 2024, DOI: 10.1021/ACSOMEGA.3C05669

Future alternatives to fossil fuel-based plastics could be hiding in kitchen cabinets and waste bins. Researchers are looking to foodstuffs as starting ingredients for polymer-based materials, including coffee grounds, tomato peels and gluten. New products made from these sustainable resources are reported in three papers recently published in ACS journals. Reporters can request free access to these papers by emailing newsroom@acs.org.

1. Coffee grounds to coffee tables. Researchers have created a material suitable for large-format 3D printing by mixing leftover grounds into biobased polylactic acid. As a proof of concept, the team used the plastic composite to 3D print a life-sized side table, as described in the open access journal ACS Omega.
2. Tomato peels to high-tech bioplastic. A study in ACS Sustainable Chemistry & Engineering details a tomato-based polyester plastic that remembers its previous shapes. A ring made of the yellow material was warped at a high temperature, then placed in a warm water bath set at 140 degrees Fahrenheit, where it snapped back to its original desired shape. This proof-of-concept shows how biobased polyesters could be made with an abundant agricultural and food waste.
3. Gluten to a compostable composite. A team created the biobased composite by combining wheat gluten — sometimes added to bread dough for extra chewiness — and carbon fibers. The research reported in the open access journal ACS Omega illustrates how the gluten-based material had a similar strength to fossil fuel-based plastics, yet broke down within 30 days in soil and didn’t impact either the germination or growth of grass seeds. The team says the design could allow future items to be molded into any shape or size.

This tomato-based polyester plastic can remember its previous shapes.

CREDIT

Adapted from ACS Sustainable Chemistry & Engineering 2024, DOI: 10.1021/acssuschemeng.3c05713 

Combining wheat gluten and carbon fibers produced this strong composite that’s also compostable.

CREDIT

ACS Omega 2024, DOI: 10.1021/acsomega.3c07711

The American Chemical Society (ACS) is a nonprofit organization chartered by the U.S. Congress. ACS’ mission is to advance the broader chemistry enterprise and its practitioners for the benefit of Earth and all its people. The Society is a global leader in promoting excellence in science education and providing access to chemistry-related information and research through its multiple research solutions, peer-reviewed journals, scientific conferences, eBooks and weekly news periodical Chemical & Engineering News. ACS journals are among the most cited, most trusted and most read within the scientific literature; however, ACS itself does not conduct chemical research. As a leader in scientific information solutions, its CAS division partners with global innovators to accelerate breakthroughs by curating, connecting and analyzing the world’s scientific knowledge. ACS’ main offices are in Washington, D.C., and Columbus, Ohio.

To automatically receive news releases from the American Chemical Society, contact newsroom@acs.org.

Note: ACS does not conduct research, but publishes and publicizes peer-reviewed scientific studies.

Diving deeper into our oceans: Underwater drones open new doors for global coral reef research

Industry-academia partnership takes innovation in coral e-DNA monitoring to the next level

Peer-Reviewed Publication

OKINAWA INSTITUTE OF SCIENCE AND TECHNOLOGY (OIST) GRADUATE UNIVERSITY

 

VIDEO: 

WHEN THE UNDERWATER DRONE PUSHES OUT BUBBLES, IT INDICATES THAT A SAMPLE OF SEAWATER HAS BEEN SUCCESSFULLY COLLECTED.

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CREDIT: OIST

At the Okinawa Institute of Science and Technology (OIST), scientists at the Marine Genomics Unit, in collaboration with the Japanese telecommunications company NTT Communications, have identified the genera of mesophotic corals using eDNA collected by underwater drones for the first time. Their groundbreaking research has been published in the journal Royal Society Open Science. Now, with the help of submersible robots, large-scale eDNA monitoring of corals can be conducted without relying on direct observations during scientific scuba diving or snorkeling. 

Mesophotic (‘middle-light’) coral ecosystems are light dependent tropical or subtropical habitats found at depths of 30 to 150 meters. They are unique because they host more native species compared to shallow-water coral ecosystems. Despite this, they are largely unexplored, and more research is needed to understand their basic biology. 

Researchers studying corals access these invertebrate reef builders by snorkeling and scuba diving, but these methods have limitations, especially when identifying corals at deeper depths. Using genetic material that organisms shed from their bodies into their environment – environmental DNA or eDNA – scientists can identify types of corals and other organisms living in a particular habitat, providing a powerful tool for biodiversity assessment. 

Importantly, studying the eDNA of corals offers unique advantages. First, unlike fish, corals are stationary, eliminating uncertainties about their location. Second, they constantly secrete mucus into the sea, providing plenty of coral eDNA for sampling. For this study, the researchers analyzed mitochondrial DNA, which is more abundant and of higher quality compared to nuclear DNA, improving the accuracy of their findings. To learn more about the coral eDNA metabarcording analysis methods used in this study, see here. 

Faster and easier monitoring of coral reefs 

Mesophotic coral ecosystems (MCEs) in Japan have some of the highest diversity of stony corals (Scleractinia) in the world, making them particularly important for researchers, but difficult to monitor because they are often located at deeper depths. Additionally, to accurately monitor corals, scientists require both scuba diving and taxonomy skills, which can be challenging. Existing methods for monitoring MCEs therefore impose limitations on conducting thorough surveys, and new methods are needed. 

In October 2022, Prof. Noriyuki Satoh, leader of the Marine Genomics Unit, was approached by Mr. Shinichiro Nagahama of NTT Communications who had read about his research on coral eDNA methods. Mr. Nagahama suggested using their underwater drones to collect samples from deeper coral reefs for eDNA analysis. Prof. Satoh then put forward the idea of using the drones to conduct extensive surveys of mesophotic corals at greater depths. 

Kerama National Park in Japan, about 30 km west of Okinawa Island, boasts some of the most transparent water in the Okinawa Archipelago. Often referred to as ‘Kerama blue’, these waters provided an excellent opportunity for the researchers to test this new sampling technique. They collected seawater samples — each measuring 0.5 liters — from 1 to 2 meters above the coral reefs (between 20 and 80 meters deep). The sampling sites were chosen across 24 locations within 6 different areas around the picturesque Zamami Island. The next step involved subjecting these samples to coral metabarcoding analyses, which uses Scleractinian-specific genetic markers to identify the different genera of corals present in each sample. 

From the eDNA analysis results, the researchers successfully identified corals at the genus level. The presence and absence of certain genera of stony corals shown by this method indicated that reefs around the Kerama Islands exhibited different compositions of stony corals depending on location and depth. For example, the genus Acropora had the highest ratios at 11 sites, indicating that these corals are common at Zamami Island reefs. The researchers also found that the proportion of Acropora eDNA was higher at shallow reefs and upper ridges of slopes, while the proportion of the genus Porites increased at mesophotic sites. Regarding depth, Acropora was readily detected at shallow reefs (≤15 meters), while other genera were more frequently found at deeper reefs (>20 meters).

To study corals using eDNA metabarcoding methods, further sequencing of mitochondrial genomes of stony corals is needed, and this study suggests that it may be possible to more efficiently monitor mesophotic corals at the generic level using eDNA collected by underwater drones. 

Collaborative innovation ahead 

NTT Communications has developed a new version of the original drone used for this study. In response to a request from Prof. Satoh, an additional sampler was added so that two samples can be collected during a single dive. Additionally, the cable length between the controller and drone was extended from 150 meters to 300 meters and the battery is now changeable, so researchers can continue their survey work for an entire day. 

Prof. Satoh is now working with two mesophotic coral specialists at the University of the Ryukyus, Dr. Frederick Singer and Dr. Saki Harii, to further test this method at study sites near Sesoko Island, using the new and improved drones. He hopes to revolutionize the way coral surveys are conducted. Currently, surveys are limited to very restricted spots, but with the help of these advanced underwater drones, scientists can extend their research from the shallowest regions to depths of 60 meters and beyond. “My ideal survey would include the entire spectrum of the coral reef, from the shallow waters to the mesophotic zones, and even the sandy depths. These machines provide an excellent method for conducting broader eDNA monitoring studies,” he remarked. 

Bar graph showing the distribution and approximate proportions of scleractinian corals at each monitoring site at the Kerama Islands. Names of Scleractinian coral genera are shown in different colors at the bottom. Numbers 1-24 indicate eDNA sampling sites with approximate depths in meters. SF refers to surface seawater. 

Map showing the seawater sampling sites at 6 monitoring locations around Zamami Island.

CREDIT

OIST

Corals produce a protective mucus layer that shields their tissues from the surrounding seawater. Within this mucus layer, certain substances actively combat harmful bacteria, preventing potential coral diseases. 

CREDIT

Credit: H. Yamashiro

The new and improved underwater drone with two samplers, changeable batteries, and a longer cable, makes collecting seawater samples much easier for researchers.

Dr. Koki Nishitsuji, Haruhi Narisoko, and Prof. Noriyuki Satoh (L - R) have published their research on using underwater drones to sample coral eDNA in mesophotic coral ecosystems.

CREDIT

OIST

JOURNAL

Royal Society Open Science

DOI

10.1098/rsos.221586 

ARTICLE TITLE

Possible monitoring of mesophotic scleractinian corals using an underwater mini-ROV to sample coral eDNA

ARTICLE PUBLICATION DATE

14-Feb-2024

 

How do oceans start to close? New study suggests the Atlantic may ‘soon’ enter its declining phase

Peer-Reviewed Publication

FACULTY OF SCIENCES OF THE UNIVERSITY OF LISBON

 

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THE Strait of Gibraltar PROVIDES A NATURAL PHYSICAL BARRIER BETWEEN THE COUNTRIES OF Spain (NORTH) AND Morocco (SOUTH). IN GEOLOGIC TERMS, THE 10-MILE (16-KILOMETER) STRAIT THAT SEPARATES THE TWO COUNTRIES, AS WELL AS EUROPE AND AFRICA, IS LOCATED WHERE THE TWO MAJOR TECTONIC PLATES—THE EURASIAN PLATE AND THE AFRICAN PLATE—COLLIDE.

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CREDIT: NASA, PUBLIC DOMAIN, VIA WIKIMEDIA COMMONS

A new study, resorting to computational models, predicts that a subduction zone currently below the Gibraltar Strait will propagate further inside the Atlantic and contribute to forming an Atlantic subduction system – an Atlantic ring of fire. This will happen ‘soon’ in geological terms - in approximately 20 million years.

Oceans seem eternal to our lifespan, but they are not here for long: they are born, grow and one day close. This process, which takes a few hundred million years, is called Wilson Cycle. The Atlantic, for example, was born when Pangea broke up, around 180 million years ago, and will one day close. And the Mediterranean is what remains from a big ocean – the Tethys– that once existed between Africa and Eurasia.

For an ocean like the Atlantic to stop growing and start closing, new subduction zones – places where one tectonic plate sinks below another – have to form. But subduction zones are hard to form, as it requires plates to break and bend, and plates are very strong. A way out of this “paradox” is to consider that subduction zones can migrate from a dying ocean in which they already exist – the Mediterranean – into pristine oceans – such as the Atlantic. This process was dubbed subduction invasion.

This study shows for the first time how such a direct invasion can happen. The computational, gravity-driven 3-D model predicts that a subduction zone currently below the Gibraltar Strait will propagate further inside the Atlantic and contribute to forming an Atlantic subduction system – an Atlantic ring of fire, in an analogy to the already existing structure in the Pacific. This will happen ‘soon’ in geological terms – but not before approximately 20 million years.

“Subduction invasion is inherently a three-dimensional process that requires advanced modelling tools and supercomputers that were not available a few years ago. We can now simulate the formation of the Gibraltar Arc with great detail and also how it may evolve in the deep future” explains João Duarte, first author, researcher at Instituto Dom Luiz, at Faculty of Sciences of the University of Lisbon (Ciências ULisboa) (Portugal).

This study sheds a new light on the Gibraltar subduction zone, as few authors considered it to be still active, because it has significantly slowed down in the past million years. According to these results, its slow phase will last for another 20 million years and, after that, will invade the Atlantic Ocean and accelerate. That will be the beginning of the recycling of crust on the eastern side of the Atlantic, and might be the start of the Atlantic itself beginning to close.

 “There are two other subduction zones on the other side of the Atlantic – the Lesser Antilles, in the Caribbean, and the Scotia Arc, near Antarctica. However, these subduction zones invaded the Atlantic several million years ago. Studying Gibraltar is an invaluable opportunity because it allows observing the process in its early stages when it is just happening”, adds João Duarte.

Broadly, this study shows that subduction invasion is likely a common mechanism of subduction initiation in Atlantic-type oceans, and thus plays a fundamental role in the geological evolution of our planet.

The finding that the Gibraltar subduction is still currently active has also important implications for seismic activity in the area. Subduction zones are known for producing the strongest earthquakes on Earth. Events such as the 1755 Great Lisbon Earthquake are a threat and require preparedness.

This study results from a collaboration between researchers of the Faculty of Sciences of the University of Lisbon (Portugal) – João Duarte and Filipe Rosas – and researchers of the  Johannes Gutenberg University Mainz (Germany) Nicolas Riel, Anton Popov, Christian Schuler and Boris Kaus.

 Atlantic Ocean Crustal Age Image with Plates

CREDIT

Mr. Elliot Lim, CIRES & NOAA/NCEI

JOURNAL

Geology

DOI

10.1130/G51654.1 

ARTICLE TITLE

Gibraltar subduction zone is invading the Atlantic

ARTICLE PUBLICATION DATE

13-Feb-2024

Early-stage subduction invasion

Peer-Reviewed Publication

GEOLOGICAL SOCIETY OF AMERICA

 

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MAP HIGHLIGHTING THE ATLANTIC SUBDUCTION ZONES, THE FULLY DEVELOPED LESSER ANTILLES AND SCOTIA ARCS ON THE WESTERN SIDE AND THE INCIPIENT GIBRALTAR ARC ON THE EASTERN SIDE. FROM DUARTE ET AL., 2018.

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CREDIT: JOÃO C. DUARTE

Contributed by Arianna Soldati, GSA Science Communication Fellow

Our planet’s lithosphere is broken into several tectonic plates. Their configuration is ever-shifting, as supercontinents are assembled and broken up, and oceans form, grow, and then start to close in what is known as the Wilson cycle.

In the Wilson cycle, when a supercontinent like Pangea is broken up, an interior ocean is formed. In the case of Pangea, the interior ocean is the Atlantic. This ocean has a rift in the middle, and passive margins on the side, which means no seismic or volcanic activity occurs along its shores. Destined to keep expanding, an Atlantic-type ocean will eventually become the exterior ocean of the next supercontinent. Currently, Earth’s exterior ocean is the Pacific. The Pacific also has a rift in the middle, but it is bounded by subduction zones and thus will eventually close. Along its margins, earthquakes and eruptions abound—a pattern known as the ring of fire.

The ocean-closing phase of each Wilson cycle requires the transition from passive to active (subducting) margins at the edges of the interior ocean. The oceanic crust along the coast of the Atlantic is old and heavy, so it is primed to subduct, but before it can do so, it must break and bend. The only force in nature that can break oceanic plates like these is slab pull from another subduction zone.

But this doesn’t happen spontaneously. So how does subduction initiate around interior oceans?

There currently are two subduction zones in the Atlantic: the Lesser Antilles and Scotia. But neither of them formed spontaneously in the Atlantic; they were forced by subduction zones in the Pacific during the Cretaceous and then propagated along transform margins, where the continent is narrow and there is barely a land bridge. They jumped oceans.

Today, on the eastern shore of the Atlantic, in Gibraltar, we have the opportunity to observe the very earliest stages of this process, known as subduction invasion, while the jump occurs from a different basin—in this case, the Mediterranean.

This is an incredibly valuable opportunity because the chances of observing the very start of any given tectonic process are limited. And subduction initiation is difficult to observe because it leaves almost no traces behind. Once subduction starts, it erases the record of its initial stages; the subducted plate ends up in the mantle, never to be exposed at the surface again (except in the rare case of ophiolites).

The activity of the Gibraltar subduction zone in the Mediterranean has been hotly debated. The Gibraltar arc formed in the Oligocene as a part of the Western Mediterranean subduction zones. While we can see a subducted plate in the mantle underneath it, almost no further movement is currently happening.

A new paper by Duarte et al., just published in Geology, suggests that Gibraltar is active—it is just currently experiencing a slow movement phase because the subducting slab is very narrow, and it is trying to pull down the entire Atlantic plate.

“[These are] some of the oldest pieces of crust on Earth, super strong and rigid—if it were any younger, the subducting plate would just break off and subduction would come to a halt,” explains Duarte. “Still, it is just barely strong enough to make it, and thus moves very slowly.”

A new computational, gravity-driven 3-D model, developed by the authors, shows that this slow phase will last for another 20 million years. After that, the Gibraltar subduction zone will invade the Atlantic Ocean and accelerate. That will be the beginning of the recycling of crust on the eastern side of the Atlantic, and might be the start of the Atlantic itself beginning to close, initiating a new phase in the Wilson cycle.

Broadly, this study shows that subduction invasion, the process whereby a new subduction zone forms in an exterior ocean and then migrates to an interior ocean, is likely a common mechanism of subduction initiation in Atlantic-type oceans, and thus plays a key role in the geological evolution of our planet.

Locally, the finding that the Gibraltar subduction is still currently active has important implications for seismic activity in the area. Recurrence intervals are expected to be very long during this slow phase, but the potential for high-magnitude events, such as the 1755 Lisbon earthquake, remains and requires preparedness.

Much remains to be figured out about the future of the Gibraltar arc. One of the next aspects that Duarte will focus on is determining the exact geometry of the subduction, which will require assessing the relative strength of the nearby continental margins.

Maps showing the evolution of the Gibraltar subduction zone from 30 million years ago to 50 million years into the future. From Duarte et al., 2024.

CREDIT

João C. Duarte

FEATURED ARTICLE
Gibraltar Subduction Zone Is Invading the Atlantic
João C. Duarte, Nicolas Riel, Filipe M. Rosas, Anton Popov, Christian Schuler, Boris J.P. Kaus
https://doi.org/10.1130/G51654.1
Contact: João Duarte, University of Lisbon, jdduarte@fc.ul.pt

GEOLOGY articles published ahead of print are online at https://pubs.geoscienceworld.org/geology/early-publication. Representatives of the media may obtain complimentary copies of articles by contacting Katie Busser. Please discuss articles of interest with the authors before publishing stories on their work, and please make reference to GEOLOGY in articles published. Non-media requests for articles may be directed to GSA Sales and Service, gsaservice@geosociety.org.

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DOI

10.1130/G51654.1 

ARTICLE TITLE

Gibraltar subduction zone is invading the Atlantic

ARTICLE PUBLICATION DATE

13-Feb-2024

 

Root microbes may be the secret to a better tasting cup of tea

Peer-Reviewed Publication

CELL PRESS

 

IMAGE: 

THIS PHOTOGRAPH SHOWS TEA MOUNTAIN IN WUYISHAN, FUJIAN, CHINA.

 

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CREDIT: WEI XIN

You’d think the complex flavor in a quality cup of tea would depend mainly on the tea varieties used to make it. But a study appearing in the journal Current Biology on February 15 shows that the making of a delicious cup of tea depends on another key ingredient: the collection of microbes found on tea roots. By altering that assemblage, the authors showed that they could make good-quality tea even better.

“Significant disparities in microbial communities, particularly nitrogen metabolism-related microorganisms, were identified in the roots of tea plants with varying qualities through microbiomics,” says Tongda Xu of Fujian Agriculture and Forestry University in Fujian, China. “Crucially, through the isolation and assembly of a synthetic microbial community from high-quality tea plant roots, we managed to notably enhance the amino acid content in various tea plant varieties, resulting in an improvement in tea quality.”

China harbors a wealth of genetic resources for growing tea plants. But, the researchers explain, improving the quality of tea through molecular genetic breeding methods is challenging. There’s interest in finding other ways to modify and enhance tea, perhaps including the use of microbial agents. Earlier studies showed that soil microbes living in plant roots affect the way nutrients are taken up and used within plants. In the new study, the researchers wanted to learn more about how specifically root microbes affect tea quality.

They found that the microbes in tea roots affected their uptake of ammonia, which in turn influenced the production of theanine, which is key for determining a tea’s taste. They also saw variations in the microbes colonizing different teas. By comparing tea varieties with different amounts of theanine, they identified a set of microbes that looked promising for altering nitrogen metabolism and boosting theanine levels.

They next constructed a synthetic microbial community, dubbed SynCom, that closely mirrored the one found in association with a high-theanine tea variety called Rougui. When they applied SynCom to tea roots, they found it boosted theanine levels. The microbes also allowed Arabidopsis thaliana, a plant commonly used in basic biological studies, to better tolerate low nitrogen conditions.

“The initial expectation for the synthetic microbial community derived from high-quality tea plant roots was to enhance the quality of low-quality tea plants,” says study co-author Wenxin Tang. “However, to our astonishment, we discovered that the synthetic microbial community not only enhances the quality of low-quality tea plants but also exerts a significant promoting effect on certain high-quality tea varieties. Furthermore, this effect is particularly pronounced in low-nitrogen soil conditions.”

The findings suggest that synthetically produced microbial communities could improve teas, especially when grown in nitrogen-deficient soil conditions, they say. Because tea trees require lots of nitrogen, the discovery could help to reduce the use of chemical fertilizers while promoting the quality of tea trees. The findings may have important implications for agricultural crops more broadly.

“Based on our current experimental findings, the inclusion of the SynCom21 microbial community has not only improved the absorption of ammonium nitrogen in different tea varieties but also enhanced the uptake of ammonium nitrogen in Arabidopsis thaliana,” Xu says. “This suggests that the ammonium nitrogen uptake-promoting function of SynCom21 may be applicable to various plants, including other crops.”

For instance, they say, it may allow for growing rice with improved qualities including greater protein content. They now plan to further optimize SynCom and assess its use in field trials. They also hope to learn more about how root microbes affect other secondary metabolites in tea trees.

This photograph shows Tea Mountain in Wuyishan, Fujian, China.

CREDIT

Wei Xin

This work was supported by Fujian Agriculture and Forestry University. The authors declare no competing interests.

Current Biology, Xin et al.: “Root microbiota of tea plants regulate nitrogen homeostasis and theanine synthesis to influence tea quality.” https://www.cell.com/current-biology/fulltext/S0960-9822(24)00079-4  

Current Biology (@CurrentBiology), published by Cell Press, is a bimonthly journal that features papers across all areas of biology. Current Biology strives to foster communication across fields of biology, both by publishing important findings of general interest and through highly accessible front matter for non-specialists. Visit http://www.cell.com/current-biology. To receive Cell Press media alerts, contact press@cell.com.
 

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JOURNAL

Current Biology

DOI

10.1016/j.cub.2024.01.044 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Root microbiota of tea plants regulate nitrogen homeostasis and theanine synthesis to influence tea quality

ARTICLE PUBLICATION DATE

15-Feb-2024