Two new species of already-endangered screech owls discovered in Amazon rainforest

Recordings of owls' screeches used to help tell species apart

FIELD MUSEUM

Research News

 

IMAGE: ONE OF THE NEWLY DESCRIBED SPECIES, THE XINGU SCREECH OWL. view more 

CREDIT: KLEITON SILVA

The Amazon rainforest is teeming with creatures unknown to science--and that's just in broad daylight. After dark, the forest is a whole new place, alive with nocturnal animals that have remained even more elusive to scientists than their day-shift counterparts. In a new paper in Zootaxa, researchers described two new species of screech owls that live in the Amazon and Atlantic forests, both of which are already critically endangered.

"Screech owls are considered a well-understood group compared to some other types of organisms in these areas," says John Bates, curator of birds at the Field Museum in Chicago and one of the study's authors. "But when you start listening to them and comparing them across geography, it turns out that there are things that people hadn't appreciated. That's why these new species are being described."

"Not even professional ornithologists who have worked on owls for their entire lives would agree about the actual number of species found in this group, so a study like ours has been awaited for a really long time," says Alex Aleixo, head of the research team responsible for the study, and currently curator of birds at the Finnish Museum of Natural History in the University of Helsinki, Finland.

The newly-discovered screech owls are cousins of the Eastern Screech Owls that are common in the United States. "They're cute little owls, probably five or six inches long, with tufts of feathers on their heads," says Bates. "Some are brown, some are gray, and some are in between." Until this study, the new species were lumped together with the Tawny-bellied Screech Owl and the Black-capped Screech Owl, which are found throughout South America.

Teasing out the differences between the species started with years of fieldwork in the Amazon rainforest as well as the Atlantic forest running along the eastern part of Brazil and surrounding countries. Bates, who usually conducts fieldwork during the day, says that doing fieldwork in the rainforest at night comes with new challenges. "For me it's more a feeling of fascination than being scared, but at the same time, you're running into spider webs. If you're wearing a headlight you see the eyeshine of the nocturnal animals. One time I was stepping over a log and I looked down and there was a tarantula the size of my hand just sitting there," says Bates. "If I had been a kid I would have been scared to death."

The owls that the researchers were looking for live in the trees, often a hundred feet above the forest floor. That makes studying them difficult. But the researchers had a secret weapon: the screech owls' namesake screech.

CAPTION

One of the newly described species, the Alagoas Screech Owl.

CREDIT

Gustavo Malacco.

"To draw the birds out, we used tape recordings," explains Bates. "We'd record their calls and then play them back. The owls are territorial, and when they heard the recordings, they came out to defend their territory."

The scientists compared the birds' calls and found that there were variations in the sounds they made, indicative of different species. They also examined the birds' physical appearances and took tissue samples so they could study the owls' DNA at the Field Museum's Pritzker DNA Lab.

Altogether, 252 specimens, 83 tape-recordings, and 49 genetic samples from across the range of the Tawny-bellied Screech Owl complex in South America were analyzed. A significant number of specimens were collected by the research team itself, especially the study's lead author Sidnei Dantas, who spent a good share of his time in graduate school searching for and tape-recording screech owls in South American rainforests. In addition, natural history collections and their materials collected over the centuries were essential to complete the study´s unprecedented sampling.

"The study would not have been possible if it were not for the great biological collections in Brazil and USA which I visited during my work, and that sent us essential material, either genetic and morphological. This highlights the importance of such research institutions for the progress of science and hence of the countries they represent," says Dantas, who conducted the study as part of his PhD dissertation at the Goeldi Museum in Belém and is currently working as a nature guide in Brazilian Amazonia.

The combination of genetic variation, physical differences, and unique vocalizations led the team to describe two new species in addition to the previously known Tawny-bellied Screech Owl: the Xingu Screech Owl and the Alagoas Screech Owl. The Xingu owl's scientific name is in honor of Sister Dorothy May Stang, an activist who worked with Brazilian farmers to develop sustainable practices and fight for their land rights; its common name is for the area where the owl is found near the Xingu River. The Alagoas owl's name is a reference to the northeastern Brazilian state of Alagoas where the owl is primarily found.

CAPTION

Lead author Sidnei Dantas working with owl specimens at the Field Museum.

CREDIT

John Bates, Field Museum

While the owls are new to science, they're already in danger of disappearing forever. "Both new species are threatened by deforestation," says Jason Weckstein, associate curator of Ornithology in the Academy of Natural Sciences of Drexel University and associate professor in the university's Department of Biodiversity, Earth, and Environmental Science. "The Xingu Screech Owl is endemic to the most severely burned area of the Amazon by the unprecedented 2019 fires, and the Alagoas Screech Owl should be regarded as critically endangered given the extensive forest fragmentation in the very small area where it occurs," says Weckstein, who is a co-author and began work on this project as a postdoctoral researcher at the Field Museum.

Bates says he hopes that the study will shed light on how varied the Amazon and Atlantic forests are and how simply protecting certain areas isn't enough to preserve the forests' biodiversity. "If you just say, 'Well, you know Amazonia is Amazonia, and it's big,' you don't end up prioritizing efforts to keep forests from being cut in these different parts of Amazonia. That could mean losing entire faunas in this region," says Bates.

In addition to the study's conservation implications, the authors highlight the international collaboration that made the work possible. "This study shows how important it is to train the next generation of scientists at a global level," says Bates. "That means to having students like Sidnei come from Brazil and work in the Field's Pritzker Lab and measure specimens in our collection for their research. It's a great thing to build those connections."

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What is killing bald eagles in the U.S.?

MARTIN-LUTHER-UNIVERSITÄT HALLE-WITTENBERG

Research News

 

IMAGE: BACTERIAL COLONIES OF THE CYANOBACTERIUM A. HYDRILLICOLA GROWING ON A LEAF OF THE INVASIVE AQUATIC PLANT H. VERTICILLATA. view more 

CREDIT: SUSAN WILDE

Bald eagles, as well as other wildlife, have been succumbing to a mysterious neurodegenerative disease in the southern United States since the 1990s. New research by the Martin Luther University Halle-Wittenberg (MLU) in Germany and the University of Georgia, USA, identifies the cause of these deaths: a toxin produced by cyanobacteria that grow on invasive aquatic plants. The problem is potentially exacerbated by herbicides used to control those plants. The results were published in Science.

In 1994, bald eagles were dying on a mass scale in the U.S. state of Arkansas. The animals were losing control over their bodies, and holes were developing in their brains. A previously unknown neurodegenerative disease, termed vacuolar myelinopathy (VM), was identified. "The origin of the disease was a complete mystery," says Professor Timo Niedermeyer from the Institute of Pharmacy at MLU.

Later on, American researchers found that not only eagles were affected, but also their herbivorous prey. The scientists discovered a connection to an invasive aquatic plant (Hydrilla verticillata) that grows in freshwater lakes in the affected regions. However, there were still some lakes with the aquatic plant where the disease was not manifesting. In 2005 Susan B. Wilde, a professor at the Warnell School of Forestry and Natural Resources at the University of Georgia, identified a previously unknown cyanobacterium on the leaves of Hydrilla verticillata, which appeared to be the cause of the disease. It turned out that vacuolar myelinopathy only occurs in places where the cyanobacterium colonizes the invasive plant. She called the bacterium "eagle killer that grows on Hydrilla": Aetokthonos hydrillicola.

"I stumbled across a press release issued by the university in Georgia and was fascinated by these findings, because I've worked with cyanobacteria for years," says Niedermeyer. He had samples sent to him, cultivated the bacteria in the laboratory and sent them back to the U.S. for further testing. But the tests came back negative: The bacteria from the lab did not induce the disease. "It's not just the birds that were going crazy, we were too. We wanted to figure this out," says Niedermeyer. Once again, he had colonized leaves sent to him. Steffen Breinlinger, a doctoral student in his research group, then used a new imaging mass spectrometer to investigate the composition on the surface of the plant's leaf, molecule by molecule. He discovered a new substance that only occurs on the leaves where the cyanobacteria grow, but is not produced in the cultivated bacteria.

His investigations into the chemical structure of the isolated molecule showed that it contains five bromine atoms. "The structure is really spectacular," says Breinlinger. The properties are unusual for a molecule formed by bacteria. And they provide an explanation for why the toxin did not form under laboratory conditions. Standard culture media in which cyanobacteria grow do not contain bromide. "We then added bromide to our lab cultures, and - the bacteria started producing the toxin," says Breinlinger. Wilde and her colleagues tested the isolated molecule in birds, and finally, after almost a decade of research in the Wilde and Niedermeyer labs, they had the proof: the molecule does trigger VM. According to the name of the bacterium, the researchers call their discovery aetokthonotoxin, "poison that kills the eagle". "Finally, we did not only catch the murderer, but we also identified the weapon the bacteria use to kill those eagles," says Wilde.

A research group participating in the study from the Czech Academy of Sciences also found sections of DNA containing genetic information for the synthesis of the new molecule. Why the cyanobacteria form the toxin on the aquatic plants in the first place, however, has yet to be studied. One of the herbicides used to combat the invasive aquatic plant might play a crucial part in VM occurrence: It contains bromide and thus might stimulate toxin production.

The neurological disease has not yet occurred in Europe, and no instance of the toxin-forming cyanobacterium has been reported.

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The research has been supported by the Deutsche Forschungsgemeinschaft (German Research Foundation, DFG), the Czech Science Foundation GA?R, the US Department of Interior, US Fish and Wildlife Service, the Florida Fish & Wildlife Conservation Commission, the Gulf States Marine Fisheries Commission, the National Institute of Food and Agriculture McIntire-Stennis Capacity Grant and the American Eagle Foundation.

Study: Breinlinger S. et al. A cyanobacterial neurotoxin causes vacuolar myelinopathy. Science (2021). DOI: 10.1126/science.aax9050
https://science.sciencemag.org/lookup/doi/10.1126/science.aax9050

Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news rel

 

MIT engineers make filters from tree branches to purify drinking water

Prototypes tested in India show promise as a low-cost, natural filtration option

MASSACHUSETTS INSTITUTE OF TECHNOLOGY

Research N 

IMAGE: XYLEM TISSUE IN GYMNOSPERM SAPWOOD CAN BE USED?FOR?WATER FILTRATION (AS SEEN ON TOP). XYLEM IS COMPRISED OF CONDUITS THAT ARE INTERCONNECTED?BY MEMBRANES THAT? FILTER OUT?CONTAMINANTS PRESENT IN WATER (BOTTOM).... view more 

CREDIT: COURTESY: N.R. FULLER, SAYO STUDIO

The interiors of nonflowering trees such as pine and ginkgo contain sapwood lined with straw-like conduits known as xylem, which draw water up through a tree's trunk and branches. Xylem conduits are interconnected via thin membranes that act as natural sieves, filtering out bubbles from water and sap.

MIT engineers have been investigating sapwood's natural filtering ability, and have previously fabricated simple filters from peeled cross-sections of sapwood branches, demonstrating that the low-tech design effectively filters bacteria.

Now, the same team has advanced the technology and shown that it works in real-world situations. They have fabricated new xylem filters that can filter out pathogens such as E. coli and rotavirus in lab tests, and have shown that the filter can remove bacteria from contaminated spring, tap, and groundwater. They also developed simple techniques to extend the filters' shelf-life, enabling the woody disks to purify water after being stored in a dry form for at least two years.

The researchers took their techniques to India, where they made xylem filters from native trees and tested the filters with local users. Based on their feedback, the team developed a prototype of a simple filtration system, fitted with replaceable xylem filters that purified water at a rate of one liter per hour.

Their results, published today in Nature Communications, show that xylem filters have potential for use in community settings to remove bacteria and viruses from contaminated drinking water.

The researchers are exploring options to make xylem filters available at large scale, particularly in areas where contaminated drinking water is a major cause of disease and death. The team has launched an open-source website, with guidelines for designing and fabricating xylem filters from various tree types. The website is intended to support entrepreneurs, organizations, and leaders to introduce the technology to broader communities, and inspire students to perform their own science experiments with xylem filters.

"Because the raw materials are widely available and the fabrication processes are simple, one could imagine involving communities in procuring, fabricating, and distributing xylem filters," says Rohit Karnik, professor of mechanical engineering and associate department head for education at MIT. "For places where the only option has been to drink unfiltered water, we expect xylem filters would improve health, and make water drinkable."

Karnik's study co-authors are lead author Krithika Ramchander and Luda Wang of MIT's Department of Mechanical Engineering, and Megha Hegde, Anish Antony, Kendra Leith, and Amy Smith of MIT D-Lab.

Clearing the way

In their prior studies of xylem, Karnik and his colleagues found that the woody material's natural filtering ability also came with some natural limitations. As the wood dried, the branches' sieve-like membranes began to stick to the walls, reducing the filter's permeance, or ability to allow water to flow through. The filters also appeared to "self-block" over time, building up woody matter that clogged the conduits.

Surprisingly, two simple treatments overcame both limitations. By soaking small cross-sections of sapwood in hot water for an hour, then dipping them in ethanol and letting them dry, Ramchander found that the material retained its permeance, efficiently filtering water without clogging up. Its filtering could also be improved by tailoring a filter's thickness according to its tree type.

The researchers sliced and treated small cross-sections of white pine from branches around the MIT campus and showed that the resulting filters maintained a permeance comparable to commercial filters, even after being stored for up to two years, significantly extending the filters' shelf life.

The researchers also tested the filters' ability to remove contaminants such as E. coli and rotavirus -- the most common cause of diarrheal disease. The treated filters removed more than 99 percent of both contaminants, a water treatment level that meets the "two-star comprehensive protection" category set by the World Health Organization.

"We think these filters can reasonably address bacterial contaminants," Ramchander says. "But there are chemical contaminants like arsenic and fluoride where we don't know the effect yet," she notes.

Groundwork

Encouraged by their results in the lab, the researchers moved to field-test their designs in India, a country that has experienced the highest mortality rate due to water-borne disease in the world, and where safe and reliable drinking water is inaccessible to more than 160 million people.

Over two years, the engineers, including researchers in the MIT D-Lab, worked in mountain and urban regions, facilitated by local NGOs Himmotthan Society, Shramyog, Peoples Science Institute, and Essmart. They fabricated filters from native pine trees and tested them, along with filters made from ginkgo trees in the U.S., with local drinking water sources. These tests confirmed that the filters effectively removed bacteria found in the local water. The researchers also held interviews, focus groups, and design workshops to understand local communities' current water practices, and challenges and preferences for water treatment solutions. They also gathered feedback on the design.

"One of the things that scored very high with people was the fact that this filter is a natural material that everyone recognizes," Hegde says. "We also found that people in low-income households prefer to pay a smaller amount on a daily basis, versus a larger amount less frequently. That was a barrier to using existing filters, because replacement costs were too much."

With information from more than 1,000 potential users across India, they designed a prototype of a simple filtration system, fitted with a receptacle at the top that users can fill with water. The water flows down a 1-meter-long tube, through a xylem filter, and out through a valve-controlled spout. The xylem filter can be swapped out either daily or weekly, depending on a household's needs.

The team is exploring ways to produce xylem filters at larger scales, with locally available resources and in a way that would encourage people to practice water purification as part of their daily lives -- for instance, by providing replacement filters in affordable, pay-as-you-go packets.

"Xylem filters are made from inexpensive and abundantly available materials, which could be made available at local shops, where people can buy what they need, without requiring an upfront investment as is typical for other water filter cartridges," Karnik says. "For now, we've shown that xylem filters provide performance that's realistic."

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This research was supported, in part, by the Abdul Latif Jameel Water and Food Systems Lab (J-WAFS) at MIT and the MIT Tata Center for Technology and Design.

Written by Jennifer Chu, MIT News Office

Additional background

Need a water filter? Peel a branch https://news.mit.edu/2014/need-a-water-filter-peel-a-tree-branch-0226

Palm oil production can grow without converting rainforests and peatland

Nebraska agronomist: 'Potential impact is huge'

UNIVERSITY OF NEBRASKA-LINCOLN

Research News

 

IMAGE: BUNCHES IN AN OIL PALM PLANTATION IN INDONESIA. IT TAKES ABOUT 38 WEEKS FROM INITIATION UNTIL BUNCHES ARE READY FOR HARVEST. view more 

CREDIT: HENDRA SUGIANTO/UNIVERSITY OF NEBRASKA-LINCOLN

Lincoln, Neb., March 25, 2021 -- Palm oil, the most important source of vegetable oil in the world, is derived from the fruit of perennial palm trees, which are farmed year-round in mostly tropical areas. The palm fruit is harvested manually every 10 days to two weeks, then transported to a mill for processing, and ultimately exported and made into a dizzying array of products from food to toiletries to biodiesel.

"You probably ate palm oil for breakfast," said Patricio Grassini, an associate professor of agronomy at the University of Nebraska-Lincoln. "There is probably palm oil in your shampoo and for sure palm oil in your makeup."

Dozens of countries produce palm oil, but Indonesia produces approximately two-thirds of the world's supply, and demand for the product is ever-growing.

This is a double-edged sword for Indonesia and other palm-oil producing countries, Grassini said. Palm oil is a major export and contributes to the economic stability of countries that are major producers, as well as to the individual farmers who produce it. But to keep up with demand, rainforests and peatlands - valuable ecosystems that contribute greatly to biodiversity -- are often converted to palm production.

A four-year research project led by Grassini and supported by a $4 million grant from the Norwegian Ministry of Foreign Affairs suggests that keeping up with demand may not necessarily mean converting more valuable, fragile ecosystems into agricultural land.

According to research published March 25 in Nature Sustainability, palm oil yields on existing farms and plantations could be greatly increased with improved management practices. Researchers from the Indonesian Oil Palm Research Institute, the Indonesian Agency for Agriculture Research and Development, and Wageningen University in the Netherlands were also part of this project.

In Indonesia, about 42% of land used for palm oil production is owned by small holder farmers, with the rest managed by large plantations, said Juan Pablo Monzon, a UNL research assistant professor of agronomy and horticulture and first author of the published paper. "There is great potential to increase productivity of current plantations, especially in the case of smallholders' farms, where current yield is only half of what is attainable."

The research shows that palm farmers have significant opportunity to increase their production, said Grassini, one of the developers of the Global Yield Gap Atlas, a collaboration between UNL and Wageningen University in the Netherlands designed to estimate the difference between actual and potential yields for major food crops worldwide including palm oil.

"The potential impact is huge, and if we are able to realize some of that potential, that means a lot in terms of reconciling economic and environmental goals," Grassini said. "If we can produce more, we don't need to expand into new areas. But this would require the effective implementation of current Indonesia government policy and assuring that regulations are enforced so that intensification and productivity gains translate into sparing critical natural ecosystems."

The gap between the current and attainable yields could be bridged by implementing good agronomic practices, Monzon said. As a result, the country could produce 68% more palm oil on existing plantation area located in mineral soils.

Grassini and other researchers identified key management practices that could lead to larger yields. Those practices include improved harvest methods, better weed control, improved pruning and better plant nutrition. Grassini and other researchers now are working with producers, non-government organizations, Indonesian government officials and a host of other partners to put these management techniques into practice. Already they have begun to see improvements in yields.

This is exciting from both environmental and economic standpoints, Grassini said. It also stands to have a great impact on the millions of individual farmers who draw their livelihood from small palm farms often comprised of just a few acres.

"Whatever we do to help the farmers produce more palm oil on the land that they have directly impacts their income and directly impacts their families," Grassini said. "It could be the difference between sending kids to school or not."

The first phase of the research - the research that identified the yield gap - was surprising, Grassini said. Indonesia had already gone through a period of agricultural intensification that had resulted in better yields for rice and corn, and he hadn't anticipated quite so much room for improvement when it came to palm oil.

But it's the second phase of the research that really excites him. So many people from so many different backgrounds are all working together to fine-tune management strategies and put them into practice. After just 15 months, yields on test plots are already up, with potential for more growth in the future. Robust education and extension efforts will be key to fully exploit the potential for growth, Grassini said.

"I don't think you will find too many projects where people are working side-by-side on the production side, science side and environmental side," Grassini said. "All are bringing real solutions to the table and together can have a massive impact."

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Young oil palm plantation in Indonesia. Each plantation cycle is about 25 years.

CREDIT

Hendra Sugianto/University of Nebraska-Lincoln

Inhibiting impact of dust aerosols on eastern Pacific tropical cyclones from the perspective of energy transmission

INSTITUTE OF ATMOSPHERIC PHYSICS, CHINESE ACADEMY OF SCIENCES

Research News

 

IMAGE: SCHEMATIC OF THE NEGATIVE EFFECT OF DUST AEROSOLS ON THE ENERGY TRANSMISSION OF TC. view more 

CREDIT: ZHENXI ZHANG

The thermodynamic state of the tropical atmosphere plays an important role in the development of tropical cyclone (TC) intensity. A TC imports thermodynamic energy from ocean-air heat and moisture fluxes and exports heat aloft at the much colder upper troposphere, through a radially and vertically directed overturning circulation in a TC. The work done through this cycle drives the TC's winds.

A negative response of cloud water in the lower troposphere to dust aerosol optical depth (AOD) has recently been reported in Atmospheric and Oceanic Science Letters (https://doi.org/10.1016/j.aosl.2020.100028) by Dr. Zhenxi Zhang from the Inner Mongolia University of Technology, Hohhot, China, by analyzing MERRA-2 reanalysis data and GCM simulations from CMIP6.

"The explanation of this response could be that dust aerosols absorb solar radiation, promoting the evaporation of clouds. In principle, this aerosol-driven vaporization modification could affect the enthalpy of the air surrounding a tropical cyclone", explains Dr. Zhang.

According to Zhang's study, a negative association between eastern Pacific TC intensity in offshore regions and dust AOD for the years 1980-2019 was also found. "The changes in TC intensity related to dust AOD conditions should be a consequence of the anomalous enthalpy of the air surrounding a TC caused by the negative effect of dust on cloud water", concludes Zhang.

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Researchers at Stanford and Carnegie Mellon reveal cost of key climate solution

STANFORD UNIVERSITY

Research News

 

Perhaps the best hope for slowing climate change - capturing and storing carbon dioxide emissions underground - has remained elusive due in part to uncertainty about its economic feasibility.

In an effort to provide clarity on this point, researchers at Stanford University and Carnegie Mellon University have estimated the energy demands involved with a critical stage of the process. (Watch video here: https://www.youtube.com/watch?v=-ZPIwwQs9aM)

Their findings, published April 8 in Environmental Science & Technology, suggest that managing and disposing of high salinity brines - a by-product of efficient underground carbon sequestration - will impose significant energy and emissions penalties. Their work quantifies these penalties for different management scenarios and provides a framework for making the approach more energy efficient.

"Designing massive new infrastructure systems for geological carbon storage with an appreciation for how they intersect with other engineering challenges--in this case the difficulty of managing high salinity brines--will be critical to maximizing the carbon benefits and reducing the system costs," said study senior author Meagan Mauter, an associate professor of Civil and Environmental Engineering at Stanford University.

Getting to a clean, renewable energy future won't happen overnight. One of the bridges on that path will involve dealing with carbon dioxide emissions - the dominant greenhouse gas warming the Earth - as fossil fuel use winds down. That's where carbon sequestration comes in. While most climate scientists agree on the need for such an approach, there has been little clarity about the full lifecycle costs of carbon storage infrastructure.

Salty challenge

An important aspect of that analysis is understanding how we will manage brines, highly concentrated salt water that is extracted from underground reservoirs to increase carbon dioxide storage capacity and minimize earthquake risk. Saline reservoirs are the most likely storage places for captured carbon dioxide because they are large and ubiquitous, but the extracted brines have an average salt concentration that is nearly three times higher than seawater.

These brines will either need to be disposed of via deep well injection or desalinated for beneficial reuse. Pumping it underground - an approach that has been used for oil and gas industry wastewater - has been linked to increased earthquake frequency and has led to significant public backlash. But desalinating the brines is significantly more costly and energy intensive due, in part, to the efficiency limits of thermal desalination technologies. It's an essential, complex step with a potentially huge price tag.

The big picture

The new study is the first to comprehensively assess the energy penalties and carbon dioxide emissions involved with brine management as a function of various carbon transport, reservoir management and brine treatment scenarios in the U.S. The researchers focused on brine treatment associated with storing carbon from coal-fired power plants because they are the country's largest sources of carbon dioxide, the most cost-effective targets for carbon capture and their locations are generally representative of the location of carbon dioxide point sources.

Perhaps unsurprisingly, the study found higher energy penalties for brine management scenarios that prioritize treatment for reuse. In fact, brine management will impose the largest post-capture and compression energy penalty on a per-tone of carbon dioxide basis, up to an order of magnitude greater than carbon transport, according to the study.

"There is no free lunch," said study lead author Timothy Bartholomew, a former civil and environmental engineering graduate student at Carnegie Mellon University who now works for KeyLogic Systems, a contractor for the Department of Energy's National Energy Technology Laboratory. "Even engineered solutions to carbon storage will impose energy penalties and result in some carbon emissions. As a result, we need to design these systems as efficiently as possible to maximize their carbon reduction benefits."

The road forward

Solutions may be at hand.

The energy penalty of brine management can be reduced by prioritizing storage in low salinity reservoirs, minimizing the brine extraction ratio and limiting the extent of brine recovery, according to the researchers. They warn, however, that these approaches bring their own tradeoffs for transportation costs, energy penalties, reservoir storage capacity and safe rates of carbon dioxide injection into underground reservoirs. Evaluating the tradeoffs will be critical to maximizing carbon dioxide emission mitigation, minimizing financial costs and limiting environmental externalities.

"There are water-related implications for most deep decarbonization pathways," said Mauter, who is also a fellow at the Stanford Woods Institute for the Environment. "The key is understanding these constraints in sufficient detail to design around them or develop engineering solutions that mitigate their impact."

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Funding for this research provided by the National Science Foundation, the ARCS Foundation and the U.S. Department of Energy.

Biocrude passes the 2,000-hour catalyst stability test

Sewage and food waste biocrude conversion process reaches major milestone

DOE/PACIFIC NORTHWEST NATIONAL LABORATORY

Research News

 

IMAGE: WET WASTES FROM SEWAGE TREATMENT AND DISCARDED FOOD CAN PROVIDE THE RAW MATERIALS FOR AN INNOVATIVE PROCESS CALLED HYDROTHERMAL LIQUEFACTION, WHICH CONVERTS AND CONCENTRATES CARBON-CONTAINING MOLECULES INTO A LIQUID BIOCRUDE.... view more 

CREDIT: (ILLUSTRATION BY MICHAEL PERKINS | PACIFIC NORTHWEST NATIONAL LABORATORY)

RICHLAND, WASH.--A large-scale demonstration converting biocrude to renewable diesel fuel has passed a significant test, operating for more than 2,000 hours continuously without losing effectiveness. Scientists and engineers led by the U.S. Department of Energy's Pacific Northwest National Laboratory conducted the research to show that the process is robust enough to handle many kinds of raw material without failing.

"The biocrude oil came from many different sources, including wastewater sludge from Detroit, and food waste collected from prison and an army base," said John Holladay, a PNNL scientist and co-director of the joint Bioproducts Institute, a collaboration between PNNL and Washington State University. "The research showed that essentially any biocrude, regardless of wet-waste sources, could be used in the process and the catalyst remained robust during the entire run. While this is just a first step in demonstrating robustness, it is an important step."

The milestone was first described at a virtual conference organized by NextGenRoadFuels, a European consortium funded by the EU Framework Programme for Research and Innovation. It addresses the need to convert biocrude, a mixture of carbon-based polymers, into biofuels. In the near term, most expect that these biofuels will be further refined and then mixed with petroleum-based fuels used to power vehicles.  

"For the industry to consider investing in biofuel, we need these kinds of demonstrations that show durability and flexibility of the process," said Michael Thorson, a PNNL engineer and project manager.

CAPTION

This reactor turns wet waste into biocrude, which in turn feeds a refining step that turns biocrude into fuels for transportation. 

CREDIT

(Andrea Starr | Pacific Northwest National Laboratory)

Biocrude to biofuel, the crucial conversion

Just as crude oil from petroleum sources must be refined to be used in vehicles, biocrude needs to be refined into biofuel. This step provides the crucial "last mile" in a multi-step process that starts with renewables such as crop residues, food residues, forestry byproducts, algae, or sewage sludge. For the most recent demonstration, the biocrude came from a variety of sources including converted food waste salvaged from Joint Base Lewis-McChord, located near Tacoma, Wash., and Coyote Ridge Corrections Center, located in Connell, Wash. The initial step in the process, called hydrothermal liquefaction, is being actively pursued in a number of demonstration projects by teams of PNNL scientists and engineers.

The "last mile" demonstration project took place at the Bioproducts, Sciences, and Engineering Laboratory on the Richland, Wash. campus of Washington State University Tri-Cities. For 83 days, reactor technician Miki Santosa and supervisor Senthil Subramaniam fed a constant flow of biocrude into carefully honed and highly controlled reactor conditions. The hydrotreating process introduces hydrogen into a catalytic process that removes sulfur and nitrogen contaminants found in biocrude, producing a combustible end-product of long-chain alkanes, the desirable fuel used in vehicle engines. Chemist Marie Swita analyzed the biofuel product to ensure it met standards that would make it vehicle-ready.

Diverting carbon to new uses

"Processing food and sewage waste streams to extract useful fuel serves several purposes," said Thorson. Food waste contains carbon. When sent to a landfill, that food waste gets broken down by bacteria that emit methane gas, a potent greenhouse gas and contributor to climate change. Diverting that carbon to another use could reduce the use of petroleum-based fuels and have the added benefit of reducing methane emissions.

The purpose of this project was to show that the commercially available catalyst could stand up to the thousands of hours of continuous processing that would be necessary to make biofuels a realistic contributor to reducing the world's carbon footprint. But Thorson pointed out that it also showed that the biofuel product produced was of high quality, regardless of the source of biocrude?an important factor for the industry, which would likely be processing biocrude from a variety of regional sources.

Indeed, knowing that transporting biocrude to a treatment facility could be costly, modelers are looking at areas where rural and urban waste could be gathered from various sources in local hubs. For example, they are assessing the resources available within a 50-mile radius of Detroit, Mich. There, the sources of potential biocrude feedstock could include food waste, sewage sludge and cooking oil waste. In areas where food waste could be collected and diverted from landfills, much as recycling is currently collected, a processing plant could be up to 10 times larger than in rural areas and provide significant progress toward cost and emission-reduction targets for biofuels.

Commercial biofuels on the horizon

Milestones such as hours of continuous operation are being closely watched by investor groups in the U.S. and Europe, which has set aggressive goals, including being the first climate-neutral continent by 2050 and achieving a 55% reduction in greenhouse gas emissions by 2030. "A number of demonstration projects across Europe aim to commercialize this process in the next few years," Holladay said.

The next steps for the research team include gathering more sources of biocrude from various waste streams and analyzing the biofuel output for quality. In a new collaboration, PNNL will partner with a commercial waste management company to evaluate waste from many sources. Ultimately, the project will result in a database of findings from various manures and sludges, which could help decide how facilities can scale up economically.

"Since at least three-quarters of the input and output of this process consists of water, the ultimate success of any industrial scale-up will need to include a plan for dealing with wastewater," said Thorson. This too is an active area of research, with many viable options available in many locations for wastewater treatment facilities.

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DOE's Bioenergy Technologies Office has been instrumental in supporting this project, as well as the full range of technologies needed to make biofuels feasible.

Pacific Northwest National Laboratory draws on its distinguishing strengths in chemistry, Earth sciences, biology and data science to advance scientific knowledge and address challenges in sustainable energy and national security. Founded in 1965, PNNL is operated by Battelle for the U.S. Department of Energy's Office of Science, which is the single largest supporter of basic research in the physical sciences in the United States. DOE's Office of Science is working to address some of the most pressing challenges of our time. For more information, visit PNNL's News Center. Follow us on Twitter, Facebook, LinkedIn and Instagram.

Toxin in potatoes evolved from a bitter-tasting compound in tomatoes

KOBE UNIVERSITY

Research News

 

IMAGE: THE CHEMICAL STRUCTURES OF SGAS FOUND IN TOMATOES AND POTATOES. view more 

CREDIT: RYOTA AKIYAMA/MASAHARU MIZUTANI

A multi-institutional collaboration has revealed that α-solanine, a toxic compound found in potato plants, is a divergent of the bitter-tasting α-tomatine, which is found in tomato plants. The research group included Associate Professor MIZUTANI Masaharu and Researcher AKIYAMA Ryota et al. of Kobe University's Graduate School of Agricultural Science, Assistant Professor WATANABE Bunta of Kyoto University's Institute for Chemical Research, Senior Research Scientist UMEMOTO Naoyuki of the RIKEN Center for Sustainable Resource Science, and Professor MURANAKA Toshiya of Osaka University's Graduate School of Engineering.

It is hoped that these research results can be used in potato breeding as a basis for suppressing the synthetization of poisonous compounds.

These research results were published in the international academic journal 'Nature Communications' on February 26.

Main Points

• α-solanine is a toxic steroidal glycoalkaloid (SGA) (*1) found in potatoes.
• Tomato's α-tomatine is astringent-tasting SGA that accumulates inside unripe fruits.
• Based on their chemical structures, SGAs can be divided into two general classes, solanidanes (*2, e.g.α-solanine) and spirosolanes (*3, e.g. α-tomatine).
• The research group revealed that the toxic α-solanine in potatoes is biosynthesized from spirosolane.
• They discovered that the dioxygenase DPS (*4) is the key enzyme for this catalytic conversion.
• It was also revealed that the α-solanine biosynthesis pathway in potatoes diverged from the spirosolane biosynthesis pathway due to the evolution of DPS.

CAPTION

The research group discovered that the enzyme DPS is a catalyst for this reaction (indicated by the red arrow).

CREDIT

Ryota Akiyama/Masaharu Mizutani

Research Background

α-solanine is a type of toxic steroidal glycoalkaloid (SGA), which accumulates in the green skin on potato tubers (*5) and in tuber sprouts. SGA is not only found in potatoes but also in other plants of the Solanaceae family, including crops like tomatoes and eggplants. These substances are poisonous to many living things and serve as one of the plants' natural defenses. Low concentrations of SGA in potatoes cause a bitter taste and larger amounts can cause food poisoning. For this reason, biosynthesis research has been conducted with the aim of controlling the accumulation of SGA in potatoes.

Based on their skeletal chemical structures, SGAs can be divided into two general classes, solanidanes and spirosolanes (Figure 1). The potato toxinα-solanine is an example of a solanidane, whereas α-tomatine, which accumulates inside unripe tomatoes, is a spirosolane. It is known that both classes of SGA are biosynthesized from cholesterol. Up until now, several genes that encode the catalytic enzymes in SGA biosynthesis have been discovered and potato and tomato plants share these enzymes in the common pathway of SGA biosynthesis. However, the steps and enzymes involved in the metabolic branch point between solanidane- skeleton and spirosolane-skeleton formation remains an unsolved mystery.

This research group showed that the potato toxinα-solanine is biosynthesized from spirosolane. In a world first, they discovered that the dioxygenase DPS is the key to this conversion.

CAPTION

Metabolic reactions of spirosolane in tomatoes and potatoes.

CREDIT

Ryota Akiyama/Masaharu Mizutani

Research Findings

Potatoes contain the toxic solanidanes α-solanine and α-chaconine. The research group investigated theα-solanine biosynthesis pathway in potato plants. Using genome editing, they disrupted the biosynthetic enzyme gene in potato so that it was unable to produceα-solanine. Feeding α-tomatine (a spirosolane found in tomatoes) to the disruptant resulted in a metabolic conversion to the corresponding solanidane compound. In addition, it was found that this metabolic alteration could be suppressed with a 2-oxoglutarate dependent dioxygenase inhibitor, revealing that a dioxygenase is responsible for the oxidation reaction that synthesizes solanidanes from spirosolanes.

The researchers singled out a 2-oxoglutarate dependent dioxygenase (DPS) gene that was expressed in potato during α-solanine synthesis. To investigate this further, the researchers generated modified plants in which DPS gene expression was suppressed via RNA interference (*7). The solanidane concentrations in these modified potato plants were far lower than in the unmodified group, and spirosolanes accumulated inside the plants in place of solanidanes. Next, the researchers measured the enzymatic activity of DPS by recombining the proteins and expressing them in E. coli. The results revealed the unique catalytic role of DPS in spirosolane's conversion into solanidane (Figure 2). This proved that DPS is the key enzyme responsible for this conversion.

This research revealed that the potato's ability to produce α-solanine came about due to the evolution of DPS, which is responsible for metabolically converting spirosolanes (e.g. α-tomatine) into solanidanes. It is known that tomatoes also have an enzyme for metabolizing spirosolanes. The bitter-tasting α-tomatine is found in unripe tomatoes but is metabolized into the tasteless, non-toxic esculeoside A as the fruits ripen. The catalyst for this reaction is 23DOX (*8), which is also a dioxygenase.

From the relationship between their chromosomal positions and phylogenetic analysis, it was revealed that the α-solanine biosynthase DPS has evolved from the same precursor gene as the non-toxic α-tomatine's catalytic enzyme 23DOX. Thus, it is believed that the evolution of the dioxygenase gene that metabolizes spirosolanes is one of the main drivers of the development of structural and functional variation in SGAs.

Further Developments

Potatoes have been termed a potentially dangerous food because large concentrations of toxic α-solanine can cause food poisoning. It is hoped that these research results can provide a basis for future potato varieties in which the biosynthesis of toxic compounds is suppressed by targeting the DPS gene.

As shown in this research, the evolutionary origins of the structural diversity of SGAs provide clues towards discovering unknown SGA synthesis enzymes involved in biological functions in various plants. Illuminating these functions could pave the way for the molecular breeding of plant varieties that are able to adapt to different stressful environments.

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Glossary

1. Steroidal Glycoalkaloid (SGA): An SGA consists of alkaloids containing nitrogen atoms arranged in a skeletal steroid structure. It is a toxic alkaloid glycoside with an oligosaccharide attached to the hydroxyl group at position C3 of the steroid. SGAs are secondary metabolites that accumulate in plants of the Solanaceae family. The SGAs α-solanine and α-chaconine are found in potatoes and are known to cause food poisoning.

2. Solanidanes: The skeletal steroid structure of some SGA chemical compounds, such as α-solanine in potatoes.

3. Spirosolanes: The skeletal steroid structure of some SGA chemical compounds, such as α-tomatine in tomatoes.

4. DPS: DPS stands for Dioxygenase for Potato Solanidane synthesis. It is the key enzyme for the biosynthesis ofα-solanine in potatoes. DPS is the catalytic enzyme for the metabolic alteration of spirosolane to solanidane by C-16 hydroxylation.

5. Tuber: An enlarged underground structure in some plant species that stores nutrients. Plants with edible tubers include potato, konnyaku and Jerusalem artichoke.

6. 2-oxoglutarate dependent dioxygenase: 2-oxoglutarate dependent dioxygenases are a super family of enzymes that are water-soluble and play various roles in many biological processes. They require 2-oxoglutarate (α-ketoglutarate) and O2 to hydrate substrates.

7. RNA interference: RNA interference is a phenomenon where an antisense RNA strand, which is complimentary to a specific gene's mRNA, and a sense RNA strand become a double-stranded RNA, suppressing the expression of the gene. This knowledge forms the basis of a method to control the expression of target genes in experiments.

8. 23DOX: This enzyme hydrolyzes spirosolane at C-23. It is part of the 2-oxoglutarate dependent dioxygenase super family of enzymes. In tomato plants, it hydrolyzes the bitter-tasting SGA α-tomatine at C-23.

Acknowledgements

This research was partially funded by the following:

• A Grant-in-Aid for JSPS Fellows for the research project entitled 'The chemical evolution of steroidal glycoalkaloids in Solanaceae' (grant number JP19J10750, recipient: Akiyama Ryota).
• The Japanese Ministry of Agriculture, Forestry and Fisheries' 'Development of new varieties and breeding materials in crops by genome editing' program for advancing research.
• The Cross-ministerial Strategic Innovation Promotion (SIP) Program.

Journal Information:

Title: "The biosynthetic pathway of potato solanidanes diverged from that of spirosolanes due to evolution of a dioxygenase" DOI: 10.1038/s41467-021-21546-0

Authors: Ryota Akiyama1, Bunta Watanabe2, Masaru Nakayasu1†, Hyoung Jae Lee1, Junpei Kato1, Naoyuki Umemoto3, Toshiya Muranaka4, Kazuki Saito3,5, Yukihiro Sugimoto1, Masaharu Mizutani1

1. Graduate School of Agricultural Science, Kobe University. 2. Institute for Chemical Research, Kyoto University. 3. RIKEN Center for Sustainable Resource Science. 4. Department of Biotechnology, Graduate School of Engineering, Osaka University. 5. Graduate School of Pharmaceutical Sciences, Chiba University. †Currently a graduate student at the Research Institute for Sustainable Humanosphere, Kyoto University.

Journal: Nature Communications

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