Courtesy of Bryce Brownfield/Cornell University

Researchers genetically manipulated Vibrio natriegens to improve its ability to adsorb rare earth elements

January 25, 2024

Cornell Researchers Improve On Ability of Bacteria To Efficiently Extract Rare Earth Elements

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Cornell researchers recently used genetic engineering to improve the extraction of rare earth elements using a bacteria called Vibrio natriegens.

Rare earth elements are a group of metallic elements with chemical similarities including scandium, yttrium and the lanthanides. According to the paper, published in the journal ACS Synthetic Biology, bacteria can provide a positive alternative to outdated and environmentally harmful methods of REE extraction. 

According to co-lead author Sean Medin grad, REEs are components of sustainable technology like magnets, electric vehicles and wind turbines. However, the methods used to obtain high purity REEs often involve toxic solvents, high temperatures and a significant carbon impact. In their paper, Medin and co-lead author Anastacia Dressel ’24 demonstrated genetic engineering to make V. natriegens better suited for extracting the elements without emitting such pollutants. 

“I’m interested in finding any way we can use synthetic biology to solve problems to do with climate change, and that involves reinventing our world’s energy system,” said Prof. Buz Barstow, biological and environmental engineering, who leads the lab which oversees the research, in an interview with the Sun. “Rare earths are something that just really took off for us.” 

V. natriegens is a good candidate for extracting REEs from the environment due to many natural qualities of the bacteria useful to lab research. According to co-author and postdoctoral associate David Specht M.Eng. ’18 Ph.D. ’21, V. natriegens has a number of advantages that make it easy to work with. Not only is V. natriegens the fastest growing organism on earth, but it also grows at room temperature and can be engineered with many of the same genetic tools used with E. Coli, conventionally one of the easiest organisms to work with.

The natural process at the heart of extracting REEs with bacteria is biosorption, a passive process that occurs when a substance from the environment, like REEs, sticks to the outside of a bacteria. V. natriegens is one of the bacteria capable of biosorbing REEs.

Barstow was inspired by previous research which suggested that biosorption could be selective — meaning certain bacteria appeared to prefer sticking to some elements over others. This selectivity made biosorption a potential tool in element processing. 

In the planned application of this research, after biosorption, the researchers would wash the bacteria and dissolve the REEs into a solution. Then, by exposing the bacteria to that new solution, the biosorption process would repeat. Due to this selectivity for certain elements, the paper predicts that a repetition of the process results in a REE solution of high purity. According to Barstow, biosorption causes REEs to stick to bacteria but not that well — like a sticky note — making this purification process very easy.

The researchers genetically engineered V. natriegens by inducing random mutations — a necessary process that allows the bacteria to mutate into a more selective version with a greater capacity to adsorb REEs.

“It’s very unlikely that we’re going to find organisms that really selectively interact with one rare earth metal. We’re trying to do something that doesn’t exist in nature,” Specht said in an interview with the Sun. 

Throughout three rounds of mutations, the researchers selected samples of bacteria and screened them to determine the extent of biosorption. One version of V. natriegens improved biosorption by 210 percent for the REE dysprosium, a common component of magnets. 

The researchers also observed an increase in selectivity between the lightest and heaviest REEs, indicating further potential to improve V. natriegens’ capability as an REE separator.

However, despite improving the biosorption capacity and selectivity, the researchers remain unsure exactly how particular genes contributed to the change.

“I explored a little bit of the genetics here, but it’s very circumstantial,” Medin said in an interview with the Sun. “[After scaling up and optimizing] I might actually be able to see — What’s the actual genetic basis? How can I actually mess with this a little bit better? That’s something that I’m looking forward to.” 

Medin is continuing to research biosorption as a method of REE extraction at REEgen, a startup company in Cornell’s Praxis Center for Venture Development, where he is also working on the technology to separate the REEs from the bacteria. REEgen, co-founded by Medin and Alexa Schmitz Ph.D. ’18, is dedicated to utilizing biology to extract rare earths without the environmental cost, thus providing sustainably sourced materials to create more sustainable energy technologies.

“I think that biology is going to help us build a revolutionary new sustainable energy infrastructure,” Barstow said. “I would be even more surprised if [by the end of the century] there wasn’t at least one or two important energy technologies that were based on syn[thetic] bio[logy].”