PARC Presents Practical Possibilities

Robert Blankenship, director of PARC, has more than 40 years’ experience researching photosynthesis, and he is one of the world’s most esteemed photosynthesis experts. He came to Washington University in 2006 with appointments in both biology and chemistry in Arts & Sciences, after 21 years at Arizona State University, where he was chair of chemistry and biochemistry. Through the years, Blankenship has revealed the complex evolutionary histories of this metabolic process in analyzing whole bacterial genomes. Combining genomic and molecular evolution techniques and biochemical analyses, he also has identified and characterized previously unknown enzyme complexes with novel activities.

Expanding the solar spectrum of photosynthetic plants and bacteria is a prime goal of PARC, which focuses on basic scientific research. In less than three years of existence, PARC researchers have made important strides toward improving light harvesting with potential impacts in agriculture, solar energy and green chemical manufacturing, while lessening reliance on non-renewable fossil fuels.

Harvesting solar power through plants or other organisms that would be genetically altered with the chlorophyll d gene could make them solar power factories that generate and store solar energy. A seven-foot-tall corn plant genetically tailored with the chlorophyll d gene to be expressed at the very base of its stalk, for instance, would absorb “red edge” light, while the rest of the plant synthesized chlorophyll a, absorbing short wave light. The base could store energy without competing with any other part of the plant for photosynthesis, as the rest only makes chlorophyll a. This altered corn using the chlorophyll d gene could become a super plant because of its enhanced ability to harness energy from the sun.

In agriculture, improved sunlight harvest could lead to faster crop maturations, and, in northern hemisphere countries, where light is weaker, tapping into the red spectra could enhance crop production.

The production of useful chemicals today is overly reliant upon crude oil as feedstock, which is finite and polluting. PARC PI Himadri B. Pakrasi has worked for decades with cyanobacteria, which use additional wavelength red light in photosynthesis and can produce a biodiesel fuel that can power vehicles and heat and cool buildings. His PARC research group of 10 scientists is looking at many different natural antenna systems. He believes that cyanobacteria will find their first practical niche in making useful chemicals for the production of such staples as nylon and polyester, for example, and, before the middle of this century, will provide alternative fuels for the American public.

Blankenship says that there are a dozen different classes of antennas across the plant and photosynthetic bacteria domains, and they vary widely in structure and composition. Yet, amazingly, they all do the same thing. Even more amazing is the fact that the research team led by Dewey Holten, PARC associate director, is able to produce analogs of the native chlorophylls that utilize many more colors of the solar spectrum. This sets the stage for breakthroughs in solar cells and devices such as electrolysers that split water, for instance — energy systems that show great promise.

“We’re coming to grips with the basic science of the antenna system the way that researchers grew to understand nuclear magnetic resonance, which ultimately blossomed into magnetic resonance imaging (MRI),” Blankenship says. “MRI, which touches millions of lives daily, was largely unanticipated, and it’s likely future developments based on PARC research will be too.”


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