Can algae soak up loads of carbon to help save the planet?

An international team of scientists, from the eastern shores of United States to the southern tip of Italy, has stumbled upon an exciting discovery – a new strain of cyanobacteria called Chonkus that thrives on carbon dioxide (CO2) and effortlessly settles in water.

This unique alga, affectionately called Chonkus, has been discovered off the Sicilian island of Vulcano, where marine CO2 is plentiful thanks to shallow volcanic vents.

The team was intrigued by the idea of what happens when regular CO2 limitations are removed, an environment in which organisms might have the potential to amplify their growth.

Algae thriving in carbon-rich environments

Dr. Max Schubert was a staff scientist at the Wyss Institute at Harvard University when the research was conducted and is now lead project scientist at Align to Innovate.

“Dissolved carbon is relatively dilute compared to all the other molecules in the ocean, and that limits the growth of photosynthetic organisms that live there,” noted Dr. Schubert.

“We decided to investigate what happens when you alleviate that limiting factor by going to a place with plenty of carbon, where some organisms could have evolved the ability to use it to galvanize their growth.”

However, the team uncovered an organism that defied this limitation. Dr. Schubert believes that Chonkus has exciting features that could be beneficial to humans.

Bringing the ocean to the lab

The story began nine years ago when Dr. Schubert and Dr. Braden Tierney shared a lab at Harvard Medical School (HMS) under the guidance of Dr. George Church.

Focused on creating tools for directed evolution of bacteria, Dr. Schubert expanded his research. In 2019, he won a proposal at the HMS Consortium for Space Genetics’ Symposium on Climate Change, allowing him to explore cyanobacteria.

Meanwhile, Dr. Tierney had his sights set on exploring microbes living in shallow seeps. He partnered with scientists at the University of Palermo in Sicily and drew upon Dr. Schubert’s expertise to understand the cyanobacteria.

What followed was an expedition that brought together a motley crew of scientists from institutions ranging from the Wyss Institute, HMS, and MIT to the National Renewable Energy Laboratory in Colorado, along with multiple Italian establishments.

A sea of possibilities

Venturing into the CO2-rich waters off the coast of Vulcano, the team collected water samples that were then shipped to Boston. Here, Dr. Schubert and his team isolated and studied the microorganisms living within.

The journey started by recreating an environment that would allow cyanobacteria to flourish – plenty of light, warmth, and CO2.

The outcome? Two strains of fast-growing cyanobacteria: UTEX 3221 and UTEX 3222. Chonkus, formally known as UTEX 3222, was selected due to its single-celled growth, making it easier to compare with existing strains.

Using algae to sequester carbon

Chonkus possesses several interesting traits, including carbon-rich storage granules within its cells, large colonies, higher carbon content, and – most notably – a natural tendency to sink fast in water.

“Many of the traits that we observed in Chonkus aren’t inherently useful in their natural environment, but are very useful to humans,” said Dr. Tierney.

“Aquatic organisms naturally grow at very low density, but being able to grow to a high density at higher temperatures is very helpful in the industrial environments that we use to manufacture many goods and products, and can help sequester more carbon.”

Potential beyond carbon sequestration

The team is excited about the potential applications of the algae beyond carbon sequestration. Due to its rapid and dense growth pattern, Chonkus could be used to more efficiently produce commodities like omega-3 fatty acids, the antioxidant astaxanthin, and spirulina.

By harnessing the ability of cyanobacteria to absorb carbon from their surroundings, the processes of carbon sequestration and biomanufacturing could be seamlessly linked.

The research has led to the founding of a non-profit organization called The Two Frontiers Project, which aims to study how life thrives in extreme environments and to explore potential applications in carbon capture, CO2 upcycling for sustainable products, and coral ecosystem restoration.

Dr. Church commends the potential of such naturally evolved cyanobacteria strains and stresses the importance of maintaining control over these experiments.

Significance of the study

Taking a cue from nature seems to be at the heart of remarkable innovation. Dr. Don Ingber, the founding director of the Wyss Institute, underlines this sentiment.

“I’m proud of this team for getting out of the lab and seeking nature’s best ideas where they’ve already developed,” said Dr. Ingber.

“This is a wonderful example of how our new Sustainable Futures Initiative is pursuing out-of-the-box approaches to confront climate change – the biggest challenge of our generation.”

The study is published in the journal Applied and Environmental Microbiology.

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