Martin Spalding, professor in the Department of Genetics, Development, and Cell Biology and associate dean for research and graduate studies in the College of Liberal Arts and Sciences, is leading a team that discovered a genetic method that can increase biomass in algae by 50 to 80%. Photo: Bob Elbert/ISU
Research at Iowa
has led to discovery of a genetic method that can increase biomass in algae by
50 to 80%.
The breakthrough comes from expressing certain genes in algae that increase
the amount of photosynthesis in the plant, which leads to more biomass.
Expressing genes means that the gene’s function is turned on.
“The key to this (increase in biomass) is combination of two genes
that increases the photosynthetic carbon conversion into organic matter by 50%
over the wild type under carbon dioxide enrichment conditions,” says
Martin Spalding, professor in the Department of Genetics, Development, and Cell
Biology and associate dean for research and graduate studies in the College of
Liberal Arts and Sciences.
Carbon enrichment conditions are those in which the algae has enough carbon
This patent-pending technology is available for licensing from the Iowa
State University Research Foundation, which also provided technology
This opens up possibilities for more and better biofuel development,
according to Spalding.
“There is no doubt in my mind that this brings us closer [to affordable,
domestic biofuel],” says Spalding.
In nature, algae are limited from growing faster because they don’t get
enough carbon dioxide from the atmosphere, says Spalding.
In environments that have relatively low levels of carbon dioxide, such as
air in earth’s atmosphere, two genes in algae, LCIA and LCIB, are expressed—or
turned on—to help capture and then channel more carbon dioxide from the air
into the cells to keep the algae alive and growing.
However, when algae are in environments with high carbon dioxide levels,
such as in soil near plant roots that are expiring carbon dioxide, the two
relevant genes shut down because the plant is getting enough carbon dioxide.
The process is similar to a car driving up a hill. The accelerator—these
two genes—is pressed and the engine works hard to climb a hill. But when going
down an incline, the driver often lets up on the accelerator since more gas
isn’t needed—the genes shut down.
The two genes are expressed—essentially keeping algae’s foot on the gas—even
when they are in a carbon dioxide-rich environment and don’t need additional
Research by Spalding’s group shows that algae can be made to produce
biomass with the accelerator floored, even in conditions where it would normally
just coast, Spalding says.
“Based on some prior research we had done, we expected to see an
increase, probably in the 10 to 20% range” he says. “But we were
surprised to see this big of an increase.”
In experiments to get the algae type (Chlamydomonas
reinhardtii) to produce more biomass, Spalding first expressed LCIA and
LCIB separately. Each effort granted a significant 10 to 15% increase in
When the two genes were expressed together, Spalding was surprised to see
the 50 to 80% biomass increase.
“Somehow these two genes are working together to increase the amount
of carbon dioxide that’s converted through photosynthesis into biomass by the
algae under conditions where you would expect there would already be enough
carbon dioxide,” says Spalding.
The excess biomass naturally becomes starch through the photosynthesis
process, and increases the biomass starch by around 80%.
By using some existing mutated
genes, Spalding can instruct the algae to make oil instead of starch. This
process requires more energy and the process results in around a 50% increase
in oil biomass.