How 'Iron Man' bacteria could help protect the environment


by Michigan State University





This Geobacter cell—which looks a bit like a gray peanut in this microscope image—is speckled with a dark coating of cobalt minerals that would be toxic to many organisms. Credit: Hunter Dulay, MSU

这个地球细菌细胞在显微镜图像中看上去有点像灰色的花生,上面散布着深色的钴矿物质,对许多生物体都有毒。图片来源:MSUHunter Dulay


When Michigan State University's Gemma Reguera first proposed her new research project to the National Science Foundation, one grant reviewer responded that the idea was not "environmentally relevant."

当密歇根州立大学的杰玛·雷格拉(Gemma Reguera)首次向国家科学基金会提出她的新研究项目时,一位拨款审查员回应说,这一想法与环境无关。

As other reviewers and the program manager didn't share this sentiment, NSF funded the proposal. And, now, Reguera's team has shown that microbes are capable of an incredible feat that could help reclaim a valuable natural resource and soak up toxic pollutants.


"The lesson is that we really need to think outside the box, especially in biology. We just know the tip of the iceberg. Microbes have been on earth for billions of years, and to think that they can't do something precludes us from so many ideas and applications," said Reguera, a professor in the Department of Microbiology and Molecular Genetics.


Reguera's team works with bacteria found in soil and sediment known as Geobacter. In its latest project, the team investigated what happened to the bacteria when they encounter cobalt.


Cobalt is a valuable but increasingly scarce metal used in batteries for electric vehicles and alloys for spacecraft. It's also highly toxic to livings things, including humans and bacteria.


"It kills a lot of microbes," Reguera said. "Cobalt penetrates their cells and wreaks havoc."

雷瓜拉说:它杀死了许多微生物。” “钴穿透细胞并造成严重破坏。

But the team suspected Geobacter might be able to escape that fate. These microbes are a hardy bunch. They can block uranium contaminants from getting into groundwater, and they can power themselves by pulling energy from minerals containing iron oxide. "They respire rust," Reguera said.


Scientists know little about how microbes interact with cobalt in the environment, but many researchers—including one grant reviewer— believed that the toxic metal would be too much for the microbes.


But Reguera's team challenged that thinking and found Geobacter to be effective cobalt "miners," extracting the metal from rust without letting it penetrate their cells and kill them. Rather, the bacteria essentially coat themselves with the metal.


"They form cobalt nanoparticles on their surface. They metallize themselves and it's like a shield that protects them," Reguera said. "It's like Iron Man when he puts on the suit."

Reguera说:它们在其表面形成钴纳米颗粒。它们会自身金属化,就像是保护它们的屏蔽层。” “就像钢铁侠穿上西装一样。

The team published its discovery in the journal Frontiers in Microbiology, with the research article first appearing online in late November, 2020.

该小组在《微生物学前沿》(Frontiers in Microbiology)中发表了这一发现,该研究文章于202011月下旬首次在线发表。

The Spartan team included Kazem Kashefi, an assistant professor in the Department of Microbiology and Molecular Genetics, and graduate students Hunter Dulay and Marcela Tabares, who are "two amazing and relatively junior investigators," Reguera said.

斯巴达团队的成员包括微生物学和分子遗传学系的助理教授Kazem Kashefi以及研究生Hunter DulayMarcela Tabares,他们是两个令人惊叹且相对初级的研究者,” Reguera说。

She sees this discovery as a proof-of-concept that opens the door to a number of exciting possibilities. For example, Geobacter could form the basis of new biotechnology built to reclaim and recycle cobalt


from lithium-ion batteries, reducing the nation's dependence on foreign cobalt mines.


It also invites researchers to study Geobacter as a means to soak up other toxic metals that were previously believed to be death sentences for the bacteria. Reguera is particularly interested in seeing if Geobacter could help clean up cadmium, a metal that's found in industrial pollution that disproportionately affects America's most disadvantaged communities.


"This is a reminder to be creative and not limited in the possibilities. Research is the freedom to explore, to search and search and search,"


Reguera said. "We have textbook opinions about what microbes can and should do, but life is so diverse and colorful. There are other processes out there waiting to be discovered."







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