I understand that you're leaving the country this week? Where are you going?
I'm going to the United Kingdom. I'll be on sabbatical at Glasgow University and then a little later at The University of Sheffield.
Your work addresses photosynthesis and light harvesting in a variety of photosynthetic bacteria. What is your lab like? I'm picturing lots of brightly-litincubators churning away.
In this picture (see right) you can see cultures growing in the lab. We like to grow big cultures. That big one in the middle is 80 L. We have one lab that's set up to do cultures like the ones in the picture. We grow a whole range of different types of photosynthetic organisms, including green sulfur bacteria, purple bacteria, cyanobacteria, and some algae. But most of our focus is on the bacterial phototrophs, particularly the anoxygenic phototrophs.
You're the Founding Director of the Photosynthetic Antenna Research Center (PARC), a DOE Energy Frontier Research Center. What are photosynthetic antennas and what have you learned about them lately?
For light to be utilized, it first has to be absorbed by a molecule. An antenna is like a big satellite dish—a collection of molecules that serve to absorb the light then focus the energy to a central complex called a reaction center, which does electron transfer. These all happen on the molecular scale.
We have a lot of different projects going on in PARC. Its research portfolio is divided into three themes: one is natural antennas—the ones found in natural organisms, which is where most of my work is focused. We also have biohybrid antenna systems, and which is where we take a natural complex, isolated from an organism, and then use it with an inorganic substrate to make a device that will do electron transfer or energy transfer of some sort. The third theme is bioinspired antennas, where we have things that we make completely synthetically, which oftentimes involves making synthetic proteins and attaching laboratory-designed pigments to them.
In terms of new developments there, one of the projects that I'm involved in is using native mass spectrophotometry to investigate antenna complexes. You can measure the mass of the entire protein complex including its subunit structure and the associated cofactors, such as chlorophylls. That gives us a lot of insight into how these complexes are put together and possibly how they're assembled.
In one of your recent papers, you and your co-authors compared the efficiency of photosynthetic and photovoltaic processes. Each process takes in sunlight energy, but photosynthesis produces biomass or chemical fuels, while photovoltaics produces nonstored electrical current. This seems like apples and oranges. What is the point of these comparisons and what did you find?
They're both solar conversion processes—they both take sunlight and convert it to energy that can be used for some other purpose. So they have a general similarity. They’re quite different in terms of the mechanism and the details. They produce different forms of energy. An organism will produce biomass, whereas the photovoltaic process mainly produces electricity, but you can make a comparison of the energy conversion efficiencies of the systems if you're careful to do as much as you can to use the same methods and the same definitions of efficiency.
So that’s what this paper was about—to take the broad view of photosynthetic and photovoltaic organisms. The interesting thing is that photosynthesis is not as efficient as a solar cell. In a corn field, typically about 1% of the energy that falls on the field is converted to energy that can be captured as biomass. One of the points of the paper was to identify why photosynthesis is so inefficient and propose ways to modify the process with modern techniques. There's a lot of interest and excitement in that area right now. A number of people have identified steps in the process that are losses and can possibly be remedied by doing intelligent sorts of manipulations.
You've been working in photosynthesis for some time now. How has the field changed since you got your start?
It's changed a lot in the years since I've been involved. The field is now much more molecular in focus in that most everything we think about goes down to the molecular level. We probe individual molecules in the complex with spectroscopic techniques or genetic techniques, etc. When I first started it didn't involve nearly so much emphasis on the molecular level. I think that's a good change—it gets us to the level where things really happen in the system and gives us a deeper understanding.
And to what extent has growing public awareness of renewable modes of energy generation changed the field?
It has put a lot more emphasis on research in terms of biofuels and so on. I think it’s a great time to study photosynthesis. There's more money available now from places like the Department of Energy and there are lots of start-up companies doing things with photosynthesis. I think it's a golden age of research in this area.
Where do you see your field in 10 years?
I think in 10 years we will have made real strides in improving the efficiency of energy capture. I think this will have a huge impact in energy production and bioenergy, but I think the biggest impact may come in agriculture. Improving the efficiency of crop plants has the potential to bring a second green revolution. You could get significantly higher crop yields and that could, of course, have a huge impact.
If you had to change careers today and you could do anything, what would you do?
I dream about that sometimes. I might want to be a geologist. One of the things we do a lot of is work with geologists to study the fossil record and biogeochemistry. Another part of me would like to be an x-ray crystallographer—I think that’s a fantastically important area. But I wouldn't change anything—I don't regret my choices.
What’s your favorite science book?
I just read a book that I found really interesting. It's really made an impression on me—it's called Darwin's Sacred Cause. I've read lots of books about Darwin, I'm very much a Darwin fan, but this one talks about how a hatred of slavery shaped his views on human evolution.
What is something about you that most people don’t know?
Perhaps my greatest claim to fame is that I appear for a very short period in the Grateful Dead movie. When I was grad student in Berkeley in the 70's we would go over and watch the Grateful Dead in San Francisco. One time they were filming for the Grateful Dead movie and I'm there in a scene in the snack bar—I'm kind of the background, and I have on a UC Berkeley t-shirt.