Metalloproteins? Breakthrough Could Speed Algae-Based Fuel Research

Mimicry of newly discovered chemical processes in microbes opens new possibilities

Biomimicry is the big buzz word in cleantech these days, referring to the scientific effort to copy the systems and processes of nature to solve human problems. Now researchers at Lawrence Berkeley National Labs have found a new treasure trove of metal-driven chemical processes in microbes that have the potential to speed the pace of clean energy breakthroughs.

According to a study released Monday, there are many more metal-containing proteins in microbes than previously recognized, which means that there is a broader and more diverse array of chemical processes that scientists can now consider mimicking.

"The implication is that evolution has produced many more ways to do chemistry than we previously thought, and that really opens doors," Steve Yannone, a member of the research team from Berkeley Lab's Life Sciences Division, told SolveClimate.

It's an important piece of basic science that points the way to a more complete understanding of the under-appreciated role of metals in microbiology as well as the Earth's climate. The hope is that it could be instrumental in cracking the code for next-generation biofuels, and other innovations.

The study surveyed three microbes to pinpoint their chemical makeup and the processes taking place within each organism. What's important is not just what the scientists found—many more chemical processes and metalloproteins than were previously thought to exist—but how they found it.

The traditional route for studying a microbe, according to Yannone, is first to sequence it genetically, and then to pinpoint interesting proteins within its structure for further study. That process can be complicated and time-consuming. By combining two study techniques, the LBL researchers were able to identify far more in the microbes in far less time.

Biochemical fractionation first enabled them to take apart a microbe while keeping its proteins intact and stable, allowing proteins to be analyzed in their natural state. Researchers then used a form of mass spectrometry to identify the makeup of the proteins, in some cases revealing extremely low quantities of individual metals within the proteins.

These new techniques could have meaningful implications for a number of clean technologies. The success of algae-based biofuel, for example, relies in large part on pinpointing algal strains that are high in lipids and thus suited to producing biodiesel.

But there are thousands of algal strains on the planet, and streamlining the process of sorting through them, short of mapping every single one, would be of great benefit to the algae-based fuel industry. The new tools LBL researchers developed would allow scientists to more easily survey, say, several hundred algal strains and immediately eliminate those that are obviously poorly suited feedstocks for biofuel. The others could be studied in greater depth for evidence of further promise. This approach could also be applied to cellulosic ethanol.

"If you want to degrade cellulose to make biofuel, and you know the enzymes involved require a specific metal-driven chemistry, then you can use this technique to find those enzymes in microbes," Yannone said.

The possible applications of this basic science are far-ranging, but given that the research is being funded by the Department of Energy,  for the time being the focus of the research team's work is targeted at renewable energy generation, carbon sequestration and remediation of contaminated sites.

The study is part of DOE's investment in foundational science, so the eventual applications are likely still a long way off. Nonetheless, the team's discoveries are important.  

"We found that they [microbes] are a lot more active than we thought and that what they do is more complicated than we thought," Yannone said.

"Microbes have evolved amazingly clever solutions to do different biochemical processes to live in the many environments they occupy— much of this biochemistry relies on metalloproteins. We found metals we didn't even know were used in biological processes, so we need to look at these strange metalloproteins and see what they do."

As scientists document more chemical processes, new potential applications will emerge. "Evolution has done an amazing job of refining and fine-tuning chemical processes, but those processes are focused on what is best for the organism—in the case of microbes, that's producing more microbes to ensure their survival," Yannone said. "Oftentimes we can mimic some of the chemical processes but adapt or modify them to our goals."

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