A researcher shows how to get rid of mercury from soil and water by using a common fungal species
Researchers at the University of Maryland found that the fungus Metarhizium robertsii is able to remove mercury from the soil around plant roots and from fresh and saltwater
The researchers genetically engineered the fungus to produce higher levels of the mercury-cleansing enzyme
Mercury pollution of soil and water is a worldwide threat to public health.
This new research suggests that a species of fungus found in soil could provide an effective method for protecting crops grown in polluted areas
Plants are unable to take up mercury due to the presence of Metarhizium. Despite being planted in polluted soil, the plant grows normally and is edible
Metarhizium is a nearly ubiquitous fungus, and previous work has shown that it colonizes plant roots and protects them from herbivorous insects.
No one had previously determined how the fungus survived in mercury-contaminated soil, or if that had implications for the plants it usually lives with.
No one had previously determined how the fungus survived in mercury-contaminated soil, or if that had implications for the plants it usually lives with.
A group of researchers had previously sequenced the genome of Metarhizium, and noticed that it contains two genes that are very similar to genes present in a bacterium known to detoxify, or bioremediate, mercury
For the current study, the researchers ran a variety of laboratory experiments and found that corn with Metarhizium grew just as well in either clean soil or mercury-laden soil
The plant tissues of corn grown in polluted soil were free of mercury. The two genes that were similar to those in mercury remediating bacteria were removed by the researchers
the genes for mercury protection were causing the corn to detoxify, they inserted them into another fungus that does not normally protect corn from mercury.
A micro-biological analysis found that the genes in question expressed enzymes that broke down highly toxic forms of mercury into less toxic forms of mercury
The only ways to clean up polluted soils are to remove the toxic chemicals from the soil or to stop the harmful effects of the chemicals. It can take a long time and can cost a lot of money
In order to prevent the plants from taking up the toxin, the soil around the plant roots needs to be detoxifying. There is only one known bacterium capable of using mercury.