Algae Produces more Fat for Biofuels when Starved

Algae cells make fat quickly, a finding that means they could hold promise as a sustainable, environmentally sound source of oil.

Algal lipids from microalgae are one of the best sources for biofuels-algae grow quickly, tolerate extreme weather conditions, and don't pose the same issues as biofuel crops that are grown both for fuel and food.

But using it as fuel source comes with a vexing problem, scientists say. The conditions that promote algal growth aren't the same as the conditions that allow the algae to create the maximum amount of oil.

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If algae are deprived of nitrogen, the cells become stressed and begin to produce lipids, but their growth rate slows.

And if alga is ever to become a commercially viable fuel source, scientists must ensure that not only can it produce as many lipids as possible, but also that it can grow at the fastest rate possible.

For a new study published in the journal Planta, researchers decided to look into how nitrogen starvation stress induces lipid accumulation in green algae, also called chlorella.

Their findings show that lipid accumulation in algal cells begins just hours after they are starved of nitrogen-not days, as scientists previously believed.

They also found that about 30 percent of lipids produced under nitrogen stress occurred as the membrane began to degrade inside each cell, the cell recycling the membrane lipids to oil.

Related article: Algae Creeps Slowly Towards Viability

"Our hope is that what we have done will be helpful to understand what's going on in cells under nitrogen starvation and might help us to tweak the technique where we can use the cells to make lipids but not necessarily stop growth-that's our long-term goal," says Bala Rathinasabapathi, professor of horticulture science at the University of Florida.

The next step for the researchers is to begin looking at genes and proteins involved during the cellular-stress stage, he said.

"We're working to understand that genetic network, which is important for turning on lipid accumulation," he says. "That's our next goal."

By. Mickie Anderson