Golden spruce trees: Gold forms nanoparticles in the needles – bacteria show the way

University of Oulu, Finland

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A new study has, for the first time, uncovered a connection between bacteria living in Norway spruce needles and gold nanoparticles. This discovery could pave the way for environmentally friendly gold exploration methods, while examining similar processes in mosses may also help remove metals from mining-impacted waters.

“Our results suggest that bacteria and other microbes living inside plants may influence the accumulation of gold in trees,” says Postdoctoral Researcher Kaisa Lehosmaa from the University of Oulu, Finland. 

It has long been known that mineral deposits release ions through oxidation and bacterial activity. These ions migrate to surface soils, where plants absorb water and nutrients. Because of this, metals can be detected in plants—or even snow—using sensitive instruments. “Such biogeochemical methods have already been used in mineral exploration, but this new research enhances our understanding of what is actually happening in the process,” explains Research Professor Maarit Middleton from the Geological Survey of Finland (GTK).

Plants host a wide range of microbial species in their tissues. “These so-called endophytic microbes may play a role in plants’ biomineralisation processes," notes Professor Anna Maria Pirttilä from the University of Oulu. In biomineralisation, inorganic substances and minerals, such as gold, accumulate and solidify inside plant tissues as part of the plant's defense mechanisms. However, the biomineralisation process remains poorly understood — it does not always occur, and when it does, it may be sporadic and localised. Identifying the mechanisms and factors behind biomineralisation is key to understanding elemental sources and developing plant-based applications in biogeochemical research and beyond.

“Our recent study provides preliminary evidence of how gold moves into plant shoots and how gold nanoparticles can form inside needles,” Dr Lehosmaa explains. “In the soil, gold is present in a soluble, liquid form. Carried by water, the gold moves into spruce needles. The tree’s microbes can then precipitate this soluble gold back into solid, nanosized particles.” This gold dust, however, cannot be seen with the naked eye, and the nanoparticles—only a millionth of a millimetre in size—are far too small to be collected for commercial use.

In the study, researchers from the University of Oulu and Geological Survey Finland collected 138 needle samples from 23 spruce trees on a satellite mineral deposit of the Kittilä gold mine in Finland. In four trees, gold nanoparticles were found inside the needles, surrounded by bacterial biofilms. DNA sequencing of these biofilms revealed that certain bacterial groups—such as P3OB-42, Cutibacterium, and Corynebacterium—were more common in gold-containing needles. “This suggests that these specific spruce-associated bacteria can help transform soluble gold into solid particles inside the needles. This insight is useful, since screening for such bacteria in plant leaves may facilitate gold exploration,” Dr Lehosmaa says.

The findings offer a foundation for bio-based and environmentally friendly mineral exploration methods. Similar approaches could also be applied to other minerals and in plants beyond spruce. “Metals can, for example, precipitate within moss tissues. Studying biomineralisation also allows us to explore how bacteria and microbes living in aquatic mosses could help remove metals from water,” Dr Lehosmaa describes another ongoing study.

The new study Biomineralized gold nanoparticles along with endophytic bacterial taxa in needles of Norway spruce (Picea abies) was published on August 28, 2025, in the internationally recognised journal Environmental Microbiome. The research was supported by the Geological Survey of Finland (GTK), the Academy of Finland, and the K.H. Renlund Foundation.

Learn more:

• A study sheds light on the symbiosis of trees, and the interactions with microbes in Chornobyl Red Forest
• Climate change and forest management can threaten blueberry microbes
• Oulu Mining School at the University of Oulu studies mineral exploration in surface layers. Read more about the methods

 

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Journal

Environmental Microbiome

TWO

10.1186/s40793-025-00770-x 

Article Title

Biomineralized gold nanoparticles along with endophytic bacterial taxa in needles of Norway spruce (Picea abies)

 

Using AI to optimize hydrogen fuel production and reduce environmental impact: Worcester Polytechnic Institute research published in Nature Chemical Engineering

Worcester Polytechnic Institute

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image: 

Fanglin Che, Associate Professor in the Department of Chemical Engineering at Worcester Polytechnic Institute

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Credit: Worcester Polytechnic Institute

To increase energy efficiency and reduce the carbon footprint of hydrogen fuel production, Fanglin Che, associate professor in the Department of Chemical Engineering at Worcester Polytechnic Institute, is leveraging the power and potential of machine learning and computational modeling. The multi-university team she leads has completed a research study that was just published in Nature Chemical Engineering. The study utilized artificial intelligence to identify catalysts with the potential to facilitate cleaner and more efficient hydrogen production.

In the paper, Che and the team present a new strategy to overcome two challenges:

• Production hurdles that prevent greater adoption of hydrogen, a fuel that does not emit carbon dioxide
• The length of time it takes to identify materials that are optimal catalysts for cleaner hydrogen production

Hurdles to hydrogen

Efforts to improve environmental sustainability and increase the availability of clean energy have long been focused on hydrogen. However, hydrogen is often produced using fossil fuels, which generate carbon dioxide.

An alternative method to produce hydrogen is to use a catalyst to break down carbon-free ammonia into its elements, which include hydrogen. However, this approach as currently designed requires very high temperatures, which are often achieved by using a lot of energy produced by fossil fuels, as well as ruthenium, an expensive rare metal that is used as a catalyst.
 

Clearing the hurdles

Che’s team proposes to reduce the carbon footprint of hydrogen production by decomposing ammonia using plasma technology, which can be done at lower temperatures than traditional chemical reactions. The researchers also propose using more commonly found and affordable metal alloys, such as iron-copper or nickel-molybdenum, as catalysts. Their analysis found this method would use less energy and perform just as well as current approaches to hydrogen production.

 

Identifying the catalysts

With more than 3,300 bimetallic alloys to consider as possible catalysts, testing each in a laboratory using traditional experiments would take a lengthy trial-and-error period. By leveraging computer models and artificial intelligence, Che’s team developed interpretable machine learning algorithms to identify earth-abundant metal alloys that outperform ruthenium catalysts in plasma-assisted ammonia decomposition. This combination of simulations and machine learning streamlined the process by quickly eliminating unsuitable materials and identified six candidates from abundant and easily sourced noncritical minerals. Laboratory tests validated the anticipated performance of the metal alloys and ultimately the researchers selected four alloys as the best catalysts.

 

Potential applications

Che’s team believes this new approach to producing hydrogen has the potential to be more affordable and cleaner than current methods. Additionally, because ammonia is easy to store and transport, this process could enable on-site hydrogen production on ships, allowing for maritime vessels to be powered by hydrogen fuel cells.

 

The research team

Che’s MAC (Modeling and AI in Catalysis) Lab at WPI combined multi-scale simulations with interpretable machine learning to develop predictions. Their work on the project is funded by the U.S. Department of Energy.

“Being published in Nature Chemical Engineering is a milestone for our lab,” says Che. “We are making great progress using computational and AI techniques to make chemical processes more energy efficient and environmentally friendly.”

Researchers at Dalian University of Technology in China conducted laboratory-based validation experiments. Researchers at Northeastern University conducted economic and environmental analysis that suggests plasma technology reduces costs and carbon emissions in hydrogen production when implemented in small, modular reactors.

 

About Worcester Polytechnic Institute 
Worcester Polytechnic Institute (WPI) is a top-tier STEM-focused research university with an R1 classification by the American Council on Education and the Carnegie Foundation for the Advancement of Teaching, recognizing the highest level of research activity. Founded in 1865, WPI was established on the principle that students learn most effectively by applying classroom theory to the practice of solving real-world problems. 

WPI’s project-based curriculum engages students in addressing pressing scientific, technological, and societal issues—both in the classroom and at more than 50 project centers across the globe. 

Today, WPI offers more than 70 bachelor’s, master’s, and doctoral degree programs across 18 academic departments in science, engineering, technology, business, the social sciences, and the humanities and arts. To help improve lives, address global challenges, and build a more sustainable world, WPI faculty and students pursue groundbreaking research in areas such as the life sciences, smart technologies, advanced materials and manufacturing, and global innovation.

Learn more at www.wpi.edu.

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Journal

Nature Chemical Engineering

Method of Research

Computational simulation/modeling

Subject of Research

Not applicable

Article Title

Interpretable machine learning-guided plasma catalysis for hydrogen production

Article Publication Date

3-Oct-2025

 

Trust more important than cost in climate policy

How do Europeans want to fight climate change? Comparing and explaining public support for a wide variety of policies

Uppsala University

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Malcolm Fairbrother, Professor at Uppsala University Conflicting Objectives Research Nexus (UUniCORN)

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Credit: Mikael Wallerstedt

How much people trust politicians affects their support for climate policies. The less trust we have in politicians, the less likely we are to accept climate policies that mean paying a price as individuals. And people are especially resistant towards taxes. These are the results of a new survey of over 6,000 respondents in four European countries.

“When people have low political trust, they are more likely to overestimate the costs of climate policies,” says Malcolm Fairbrother, Professor of Sociology, who led the study. “This explains the particularly low support for fossil fuel or carbon taxes—a policy that many economists consider the most cost-effective climate policy of all, but which, paradoxically, is least popular with the public.”

Tackling climate change requires broad popular support. Although most people think that climate change is a serious problem and want governments to act, many promising policies for addressing it encounter strong public opposition. In a new survey, researchers investigated the views of 6,000 people in Germany, Poland, Spain and Sweden and analysed their support for a wide range of climate actions. The results, published in the Journal of Public Policy, reveal clear differences in support.

“We found that regulations, such as energy efficiency requirements for cars and buildings and increased nature protection, are relatively popular measures. Subsidies and bans get a more mixed reception. Environmental taxes are generally the least popular type of policy,” Fairbrother says.

The study found, consistent with prior research, that people who have the most trust in politicians are more likely to support most climate policies. In the study, the researchers investigated why certain measures meet with such strong resistance.

According to the study, many people want ambitious climate policies, but they are reluctant to pay a high personal cost. They are also willing to support more of some kinds of measures, especially those related to regulations and energy efficiency requirements for buildings and vehicles. Support for these measures is stronger because their costs are less visible. The authors of the study suggest that policymakers should make more use of such measures, though they also stress that politicians should be honest about the costs of different potential climate policies.

“The success of climate policy depends not only on economic efficiency, but also on public support. There are strategies that are more promising for politicians to follow. More could be done simply to communicate that many climate actions, including carbon taxes, have lower costs than many people think, and are more effective. If politicians can communicate that, people will be more favourably inclined,” says Fairbrother.

The findings are relevant for several target groups. For politicians and decision makers, they provide guidance on how to design and mainstream climate action more effectively. For public authorities, organisations and opinion-makers, they show how communication can strengthen trust and thus acceptance. For the public, they can provide a better understanding of why some measures are politically feasible while others meet with resistance.

Overall, the study suggests that the path to a more ambitious climate policy depends not only on economic calculations, but also on strengthening the relationship between citizens and decision-makers.

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Journal

Journal of Public Policy

TWO

10.1017/S0143814X25100822 

Method of Research

Survey

Subject of Research

People

Article Title

How do Europeans want to fight climate change? Comparing and explaining public support for a wide variety of policies