A groundbreaking study from the University of Oulu and the Geological Survey of Finland has revealed that bacteria living inside Norway spruce needles can help convert dissolved gold into solid nanoparticles, according to of theMicroBiologist. This biomineralisation process, driven by endophytic microbes, could lead to more environmentally friendly methods of gold exploration. Researchers found gold nanoparticles surrounded by bacterial biofilms in spruce trees near Finland’s Kittilä gold mine. The discovery may also support future efforts to remove metals from mining-impacted waters using mosses and other plants. They write:
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. […]
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. […]
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.
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.
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