A surprising discovery in Finland’s forests has revealed that some Norway spruce (Picea abies) trees can accumulate trace amounts of gold in the form of nanoparticles within their needles. These nanoparticles, invisible to the naked eye, are believed to form naturally in the presence of specific bacteria living inside the plant tissues. The findings suggest that trees may play a previously unrecognized role in biogeochemical processes, potentially offering a new, environmentally friendly way to locate gold deposits.
The discovery comes from a study titled “Biomineralized gold nanoparticles along with endophytic bacterial taxa in needles of Norway spruce (Picea abies)”, published in August 2025 in the journal Biological Research by Springer Nature. Led by Dr. Johanna M. Vepsäläinen and a team of European researchers, the study examined how endophytic bacteria within the spruce needles may contribute to the formation of gold nanoparticles and explored the interactions between plants, microbes, and metals in natural ecosystems.
Gold Inside Trees?
For decades, scientists and geologists have speculated whether trees could absorb and store metals such as gold. While visible gold nuggets inside plants have never been reported, the Finnish study provides strong evidence that nanoparticles of gold can indeed exist within plant tissues. The researchers collected 138 needle samples from 23 Norway spruce trees growing in areas known for gold mineralization. Using Field Emission Scanning Electron Microscopy (FE-SEM) combined with Energy-dispersive X-ray Spectroscopy (EDS), they detected gold nanoparticles in four of the 23 trees, representing approximately 17.4% of the sampled population.
These nanoparticles were primarily located in the intercellular spaces of the mesophyll, highlighting a subtle yet significant accumulation of metal within the plant structure. Their size, measured in tens of nanometers, renders them invisible to the human eye and detectable only through high-resolution electron microscopy.
One of the most intriguing aspects of the study was the association of gold nanoparticles with endophytic bacterial communities living inside the needles. The nanoparticles were often found embedded in bacterial biofilms, suggesting a potential role of microbes in facilitating the transformation of dissolved gold ions into solid nanoparticles.
To further investigate these microbial communities, the team performed 16S rRNA sequencing, a technique that allows precise identification of bacterial taxa. They found that trees with higher gold content exhibited lower bacterial richness, although the overall diversity and community structure were not significantly different from trees with little or no gold.
Specific bacterial taxa showed strong associations with gold presence, including members of the order Myxococcales (notably “P3OB-42”), and the genera Cutibacterium, Corynebacterium, and Methylobacterium. The researchers suggest that these bacteria may have metabolic mechanisms that facilitate biomineralization, converting ionic gold absorbed from the soil into stable nanoparticle form within the needle tissue.
“Plant biogeochemistry is far more complex than we previously appreciated,” said Dr. Vepsäläinen, lead author of the study. “Our findings indicate that microbes likely play a key role in forming gold nanoparticles, though further research is needed to understand the precise mechanisms.”
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Advanced Data Analysis
To determine which bacterial taxa were most indicative of gold presence, the research team employed machine learning models, including Random Forest, AdaBoost, and ExtraTrees. These analyses identified Myxococcales and Methylobacterium as the taxa most consistently associated with nanoparticle formation, providing evidence that specific microbes may be instrumental in the biomineralization process.
These findings also have implications for biogeochemical exploration, a method of locating mineral deposits using plants as biological indicators. If trees can reliably accumulate gold nanoparticles, scientists may develop more environmentally friendly techniques for identifying potential gold reserves without invasive drilling.
“This research represents an important step forward in understanding the complex interactions between plants, microbes, and metals,” Dr. Vepsäläinen added. “It opens the door for further studies on how these processes might be harnessed for sustainable mineral exploration.”
While the quantities of gold nanoparticles found are extremely small and not economically exploitable, the study highlights a novel natural phenomenon that bridges plant science, microbiology, and geochemistry. Future research may explore whether these processes occur in other tree species, in different regions, or at varying depths in the soil. Moreover, isolating and studying the specific bacteria involved could lead to a deeper understanding of microbe-assisted biomineralization and its potential applications in environmental monitoring or biotechnology.
European Distribution of Norway Spruce
Norway spruce is widely distributed across Europe, ranging from Scandinavia (Norway, Sweden, Finland) through Central Europe (Germany, Austria, Poland, Czech Republic) and into parts of Eastern Europe, including the Carpathian Mountains. Its natural range makes it highly suitable for biogeochemical studies across multiple regions, as its widespread presence allows researchers to compare metal accumulation in different environmental conditions.
Despite its common name, the “Norway spruce” does not grow exclusively in Norway. The name originates from historical timber trade in the 18th century, when Norway exported large quantities of this species to other European countries. The nomenclature persisted, and today, Norway spruce is one of the most widely planted coniferous species in Europe. Its symmetrical shape and dense, dark green needles have also made it a popular choice as a Christmas tree, further cementing its cultural and economic significance.
Norway spruce (Picea abies) is one of the most popular choices for a Christmas tree in Europe and beyond. Its naturally symmetrical, conical shape, dense dark green needles, and sturdy branches make it ideal for hanging ornaments and lights. Traditionally, Norway spruce has been used as a Christmas tree since the 19th century, especially in countries like Germany, Austria, and Finland, where it grows abundantly. Even today, it remains a classic symbol of the festive season, prized both for its aesthetic appeal and its cultural significance. (Sulung Prasetyo)
