Algae tricked into staying up late to produce biomaterials

By Chris Hanson | November 19, 2013

Researchers at the J. Craig Venter Institute in Rockville, Md. and Waseda University in Tokyo have modified cyanobacteria’s biological clock to remain in its daytime state.

“We have shown that manipulating cyanobacteria’s clock genes can increase its production of commercially valuable biomolecules,” said Carl Johnson, professor of biological sciences at Vanderbilt University and one of the researchers on the project. “In the last 10 years, we have figured out how to stop the circadian clocks in most species of algae and in many higher plants as well, so the technique should have widespread applicability.”

During the study, researchers discovered two proteins act as switches that toggle the algae’s daytime and nighttime genes on and off. When the protein KaiA was produced in larger amounts than the KaiC protein, 95 percent of the cell’s genes that are active during daylight are turned on. The paper’s concept was to inactivate the biological clock at peak byproduct production time so that the cyanobacteria can be put in constant light for continuous production, explains Johnson.

To examine the effects of a locked biological clock, the researchers inserted genes that are used to produce commercially important compounds. They found cells with locked clocks produced 200 percent more hydrogenase, 500 percent more insulin and 700 percent more luciferase when grown in constant light than cells with normal unaltered biological clocks.

“I’m confident that the principle we introduced in this paper would also improve the production of those lipids and oils that are potential for biofuels,” Johnson said. “The way we got into this is that we were collaborating with a group that was trying to make hydrogen.”

The next phase of the study might extend research into oils produced from cyanobacteria for biofuel production and manipulating the biological clock of higher plants, Johnson said. “I think hydrogenase pathways probably are just too complicated, but some of these other kind of biofuels oils are some of the things we anticipate looking at to see if we can apply the same concept and just confirm that it would work,” he said. “The other thing I’m really interested in is people are using higher plants, as well for bioreactors. Higher plants have the same kind of issue that they have a biological clock that regulates their expression of things and that there are ways to manipulate the biological clock in higher plants. We’d like to see if we can try to apply the same principle to that situation as well.”