Scientists find gold growing in spruce tree needles
The new research suggests that substances like gold can accumulate and solidify in plant tissues and form part of its defense mechanisms.
Scientists have found a connection between bacteria in Norway spruce needles and the development of gold nanoparticles, a discovery that could one day lead to more environmentally friendly ways to study gold.
The findings are detailed in a paper in the journal Environmental Microbiome.
For their paper, experts from the University of Oulu and Geological Survey Finland analyzed 138 needle samples from 23 spruce trees situated on the Kittilä gold mine in Finland. They found gold nanoparticles surrounded by bacterial biofilms in four of them.
Scientists have known for some time that through oxidation, mineral deposits release ions and bacterial activity that migrate to the soil. Because of this, traces of different types of metals can be found in plants and snow.
Plants also host microbes. It’s believed the microbes help with a plant’s biomineralisation — i.e., the process in which a plant creates minerals that help it survive.
The new research suggests that during biomineralisation, substances like gold can accumulate and solidify in plant tissues and form part of its defense mechanisms, although this process is not fully understood.
“Our recent study provides preliminary evidence of how gold moves into plant shoots and how gold nanoparticles can form inside needles,” lead author and Postdoctoral Researcher Kaisa Lehosmaa from the University of Oulu, Finland, says in a statement.
“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.”
The gold is invisible to the naked eye -- measuring a millionth of a millimetre. That makes it too small to be harvested for commercial use. But the discovery could benefit geologists.
“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.
“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.”
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