(ORDO NEWS) — Mercury is poisonous to almost all living organisms, but there are species of bacteria, fungi and plants that can grow and even thrive in polluted soil and water.
Now scientists are proposing to use one of these species – a common parasitic fungus – to clean contaminated places from dangerous metal.
Mercury pollution is a global public health threat. Scientists are constantly looking for new ways to regulate the content of this heavy metal in soils and water bodies.
This time, an international team of researchers from China and the United States has proposed an effective and inexpensive way to bioremediate soils using a parasitic fungus.
The entomopathogenic fungus Metarhizium robertsii has attracted the attention of scientists before. It was considered as a biological means of pest control in agriculture.
Among the latter, by the way, were not only insects: Metarhizium robertsii was able to suppress the activity of other fungi, including those dangerous to cultivated plants.
Now one more item has been added to the list of useful properties of the mushroom. It turned out that in his presence, corn grown on mercury-contaminated soil does not differ in composition from ordinary corn.
After studying the genome of the fungus, scientists found two genes in it, very similar to the genes of bacteria, capable of neutralizing mercury compounds.
To make sure that these genes give the fungus the desired properties, the researchers removed them from the genome of Metarhizium robertsii , after which they planted corn again on contaminated soil.
This time, the fungus failed to save the plants: they died, poisoned by mercury. On the contrary, the transfer of Metarhizium robertsii genes into the genome of another fungus gave it the desired properties, and corn survived.
After studying the action of genes, scientists found that they encode enzymes that break down highly toxic organic mercury compounds into less toxic inorganic ones.
By introducing several copies of these genes into the fungus genome, the authors of the work obtained a highly effective tool for cleaning mercury pollution: in just 48 hours, the modified fungus was able to clean samples of fresh and salt water from dangerous mercury compounds.
In the future, scientists plan to conduct field trials and test how effective the use of a beneficial fungus is for growing crops on mercury-contaminated lands.
Since Metarhizium robertsii readily colonizes the roots of a wide variety of plant species, adding it to the soil may become a routine part of preparing a new field for planting in the near future.
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