Production of Biofuels in Eukaryotic
Algae offer the potential to produce liquid biofuels at a scale
and cost that can be competitive with existing fossil fuel production,
and biofuel production from algae will not compete with food crops
for arable land use. However, if we are to realize biofuel production
from algae in a time frame that coincides with our national needs,
we need to immediately begin the development of the molecular and
genetic tools that will allow algae to become an economically viable
biofuel source. We also need to train the young scientists whose
work will be essential to achieving the production of energy from
renewable sources. A key focus of work in my lab is to develop molecular
genetic tools in algal while training graduate students and post-doctoral
fellows in algal genetics and recombinant technologies, all of which
will be essential expertise for producing algae-derived biofuels
on a large scale.
With fossil fuel reserves dwindling, mandates requiring the reduction
of CO2 emissions, and a need for national energy independence, we
face the formidable challenge of developing sustainable forms of
carbon-neutral energy in an economically viable manner. Among these
new energy forms will surely be biofuels, fuels derived from organisms
that capture solar energy for conversion into useable forms of fuel.
Two first generation biofuels, ethanol, made by fermenting corn
or sugar cane, and biodiesel, made from vegetable oils are already
sold in the US. However, the row crops used to produce these biofuels
compete with food production and require large amounts of arable
land, water and fertilizer, making them less than ideal sources
of biofuel. Recently, attention has turned to a promising alternative:
single-celled algae. Algae grow quickly, need few added nutrients,
and get their energy from sunlight. They can be grown at a very
large scale and take CO2 from the air as part of their growth process.
Compared with crops normally used to produce vegetable oil such
as soybeans or palm, algae can produce 30 times the amount of oil
per acre . The US Department of Energy’s Aquatic Species
Program - Biodiesel from Algae” highlighted a number of advantages
of using algae as a source of biofuels and summarized their finding
with the statement “Put quite simply, microalgae are remarkable
and efficient biological factories capable of taking a waste (zero-energy)
form of carbon (CO2) and converting it into a high density liquid
form of energy (natural oil)” . Clearly, algae hold enormous
promise to become a major source of renewable energy, especially
as transportation fuels, and one that makes sense both economically
and environmentally. The challenge in realizing the potential of
algae as a biofuel source lies in our relatively limited knowledge
of algal physiology and genetics. By developing state of the art
molecular genetics tools, and by continuing to develop algal culturing
technologies, we hope to optimize algae to be an efficient and economical
source of biofuel.
To date, molecular genetic tools have been developed for only a
few algae, including the green algae Chlamydomonas reinhardtii,
and the diatoms Phaeodactylum tricornutum and Thalassiosira pseudonana.
Among these, only C. reinhardtii has well established systems for
recombinant protein expression from both the nuclear and chloroplast
genomes, and even in this species only a handful of recombinant
proteins have been expressed to any appreciable level . Importantly,
we have recently been able to demonstrate that C. reinhardtii can
be engineered to produce novel hydrocarbon molecules that are superior
biofuels, demonstrating the potential of microalgae as a biofuel
source. We are developing molecular genetic tools to allow for robust
recombinant protein expression in algae, and to engineer algae for
the production of biofuel molecules.
1. Sheehan, J., Dunahay, T., Benemann, J., Roessler, P. (1998) A
Look Back at the U.S. Department of Energy's Aquatic Species Program:
Biodiesel from Algae; Close-Out Report. U.S. Department of Energy.
2. Mayfield, S.P., et al., Chlamydomonas reinhardtii chloroplasts
as protein factories. Curr Opin Biotechnol, 2007. 18(2): p. 126-33.