Scientists at UMass Amherst engineer plant-based method of 'precious' mineral mining

Scientists at UMass Amherst Engineer Plant-based method of Precious Mineral Mining

Their research manipulates the superplant Camelina sativa to accumulate nickel, provide oil for biofuel and clean contaminated soil

 

AMHERST, Mass. — As unassuming plant—considered a noxious weed by some—may be the key to fueling a green economy in the U.S. University of Massachusetts Amherst scientists are working with Camelina sativa, a member of the mustard family, to enhance a trio of the plant’s superpowers: absorbing trace amounts of the critical mineral nickel from the soil and improving the soil’s fertility, storing that nickel in its biomass where it can be harvested and extracted for use, and, in its seeds, providing a rich source of the oil needed for biofuels.

While we may know what technology we need to transition the U.S. to a green economy, having the raw materials to do so is another matter entirely, especially when it comes to the critical materials and minerals that are the backbone of energy-efficient batteries and electrical vehicles.  All plants absorb nutrients and minerals from the soil and incorporate them into their leaves and stems, but there are some, known as “hyperaccumulators,” that have evolved the ability to accumulate specific minerals in staggering quantities.

These hyperaccumulators are the specialty of Om Parkash Dhankher, professor of molecular biology and phytoremediation in UMass Amherst’s Stockbridge School of Agriculture, who has spent the last few decades studying how plants can be used to absorb toxic elements from the soil, cleaning it through a technique called phytoremediation.

It’s only a short step from phytoremediation to phytomining, which is when the hyperaccumulated mineral is then harvested from the plant for use in industrial or manufacturing applications.

One plant in particular, Odontarrhena (formerly Alyssum murale), is known to hyperaccumulate nickel, a critical electrical component that is in short supply in the U.S. There is currently only one company actively mining nickel in the states in a conventional mine, despite the fact that nearly one million acres contain trace amounts of nickel in the topsoil. The vast majority of nickel comes from Indonesia and is processed elsewhere in the world. Because nickel is a low-level toxin, the soils in which it occurs are typically barren.

While it might seem that growing Alyssum in the U.S. would be an obvious fix — up to 3% of the plant’s biomass can be made up of nickel — Dhankher notes that it is slow-growing, low biomass, difficult to manage and takes a comparatively long nine months until it is ready to harvest. The upshot is that it takes an awful lot of Alyssum to yield a useful amount of nickel, and Alyssum is also considered an invasive species.

None of this is true of Camelina sativa, a plant that is already in wide cultivation in the U.S. Two to three crops of Camelina can be grown and harvested in the time it takes to grow a single crop of Alyssum, and its seeds are a rich source of the oil that is a core ingredient in biofuels. Thanks to Dhankher’s previous research, we now know how to enhance Camelina’s oil-producing capabilities.

“Our idea” says Dhankher, “is to determine which genes and proteins are responsible for Alyssum’s nickel hyperaccumulation, then re-engineer Camelina so that it, too, can hyperaccumulate nickel. We also want to determine which soil amendments will optimize the engineered Camelina’s ability to pull even more nickel from the soil.”

“The availability of nickel in the soil available for plant-uptake is determined by soil factors and soil health,” says Dhankher’s co-investigator, Baoshan Xing, Distinguished Professor and director of the Stockbridge School at UMass Amherst. “We will characterize these nickel-bearing soils in detail and improve the soil conditions accordingly to enhance the availability of nickel and improve the plant’s uptake of the element for hyperaccumulation.”

The result would be a minimally invasive way to extract trace amounts of nickel, returning the soil’s arability, and providing increased stocks for biofuel, all without relying on a complex and ever-evolving geopolitical situation.

“We believe that there is currently enough nickel in the barren soil in the U.S. to supply us for 50 years of phytomining,” says Dhankher. “We won’t be able to supply all of the nickel the economy needs,” he adds, “but our method could account for 20 to 30 percent of the projected demand.”

Dhankher and Xing have been awarded $1,297,055 by the U.S. Department of Energy’s Advanced Research Project’s agency to develop this new strain of nickel-loving Camelina.

“As we know, we are in the era of renewable energy,” says Dhankher. “Conventional mining in monumentally destructive, but phytomining can give us a sustainable, domestic supply of nickel to help fuel the green transition.”

A media kit, with images and all credit and caption info is available here.

 

Contacts: Om Parkash Dhankher, parkash@umass.edu

                 Daegan Miller, drmiller@umass.edu

 

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