Gene Expression Boosts Algal Biomass by 50 - 80%

Martin Spalding
Scientists at Iowa State University have taught algae to rev its biomass production engines at full speed -- even in the presence of artificially high CO2 levels. They succeeded in boosting algal biomass production by between 50% and 80% in high CO2 environments, as a result. This is a revolutionary discovery, since algae is already the most prolific biomass crop available, and grows in salt water, brackish water, wastewater, as well as fresh water.

In nature, algal growth is governed by the amount of carbon dioxide available. In relatively low carbon environments [such as Earth's atmosphere], two genes — LCIA and LCIB — are expressed to capture more CO2 and direct it into the cells, promoting growth. However, when algae live in an environment with enough CO2 to promote growth, the two genes shut down. The researchers found that expressing them, even in carbon-rich environments, significantly increases growth.

“Based on some prior research we had done, we expected to see an increase, probably in the 10 to 20 percent range” researcher Martin Spalding (pictured) said in a statement. “But we were surprised to see this big of an increase.”

Spalding first tinkered with each gene individually to see what effect it had on the algae, Chlamydomonas reinhardtii. Expressing them individually yielded a 10 to 15 percent increase in biomass. Expressing them together boosted it 50 to 80 percent.

The excess biomass naturally becomes starch, increasing the biomass around 80 percent. Using existing mutated genes, Spalding can direct the algae to make oil instead. That requires more energy, increasing biomass just 50 percent.

Algae are attractive biofuel feedstock because it grows quickly and thrives in everything from seawater to irrigation runoff to sewage. _Wired

Earth's atmosphere possesses pitifully low levels of carbon dioxide. If the levels of CO2 were reduced very far, all plant life on Earth would die, the gas is so scarce. Plant life craves more CO2, and typically thrives in greenhouses with artificial CO2 levels up to 3X atmospheric CO2 or higher. If producers could nearly double the biomass production of algae by exposure to high CO2 environments, the area required for algal growth for any particular target of production, would be cut in half.

Most analysts assume that it is the lipid component of algae that must be maximised in order to make algal biofuels and chemicals viable, but that is not necessarily true. Using a process known as IH2 (integrated hydropyrolysis and hydroconversion), raw biomass can be converted to high value chemicals and fuels directly.

Eventually, it will become easier to tweak algae to produce very high volumes of oils and other particular chemicals directly. But that may take between 10 and 20 years. There is no need to wait for that, when IH2 technology can make algal fuels and chemicals affordable much sooner. Particularly when combined with augmented growth approaches such as devised by the Iowa State researchers.