University of Minnesota: A sweeter side of algae

Imagine a crop that has potential to produce near-infinite harvests. A crop that needs minimal fertilizer, no seeds to replant fields after the harvest, and no specific growing season or climate. Imagine that crop is algae, the green gooey stuff we see growing in ponds. This is what Bioproducts and Biosystems Engineering professor Brett Barney and his research team are investigating.

“When you think about crops that produce sugar, you think about sugar cane, and you think about sugar beets,” says Barney. “Most people don’t think about algae.”

This isn’t just any algae though. This is a specific strain of algae that develops a symbiotic relationship with a microbe called Paramecium bursaria. Paramecium bursaria is found in marine water and higher-salinated fresh waters. The algae live inside the Paramecium and provide it with food (sugar), while the Paramecium gives the algae a free ride and protection.

This strain of algae first piqued Barney’s interest when the European Space Agency (ESA) published a paper on using it as a potential food source. The ESA was interested in finding methods of feeding astronauts in space for multi-year missions. That research didn’t go much further. Decades later, Barney and his team have characterized the algae and sequenced the genome to enable further studies behind the mechanism of creating sugar.

This symbiotic relationship between the Paramecium and the algae has been recognized for more than 100 years. What makes this novel are the potential uses of this sugar-excreting algae.

“We have [algae] strains that have been in culture collection for over 30 years and they still excrete sugar,” says Barney. “That symbiotic relationship has evolved and it’s stable.” He saw an opportunity for further research.

Barney and his team are interested in this sugar-creating algae for two primary reasons. First, they’d like to use the sugars to fuel bacteria used in creating fertilizer.

“If we know we have algae that produces sugar, we can do some things like grow these together [with bacteria] on agar plates,” Barney says. “They could form a symbiotic relationship together where one gives the other something in return.”

That relationship between algae and bacteria has the potential to create nitrogen, a necessary chemical for fertilizers.

There is also the potential to use the algae for carbon-capture, or removing CO2 from the atmosphere. “If you convert that carbon to something that isn’t a gas but into a commodity like sugar, that has value,” says Barney. “Then you have another driver besides just trying to pull CO2 out of the atmosphere; you’re making a new crop.”