Colorful Algae — For Fun and Profit

Professor Juergen Polle is not in the dark for long. His experimental organisms need the light in order to grow properly, and Professor Polle would like to know how to help them.

Dunaliella are microalgae, relatives of the giant kelp that washes up on the shores of California, but very different in almost every other way. These tiny organisms consist of only one cell that floats and swims in waters all over the world, rarely noticed until their numbers increase to astronomic levels.

Each cell floats in its environment absorbing chemicals from the water and sunlight from above. The chemicals it absorbs are used as building blocks for more internal structures such as proteins, DNA and some very useful compounds such as pro-Vitamin A, while the sunlight is absorbed for the energy it carries. Since sunlight is free, it takes little more than a sunny day and a pool of water to grow Dunaliella in large amounts.

This makes the growth and harvesting of these microalgae a serious economic possibility that could generate large financial rewards — if scientists like Professor Polle can only sort out a few problems in advance.

One of these problems concerns the great morphological varieties of Dunaliella and its relatives; there are a lot of them. Sometimes they look different to one another — and at other times they all look the same (or similar). Are different looking cells the same species, changing shape and color as they age and grow, or are they different species that are hard to tell apart because of their small size and strong similarities? Who knows?

As Professor Polle knows, this interesting group of organisms are not yet well characterized at the species level, and he is trying to change that by looking beneath the surface of the cell. Instead of looking at the shape or color of different Dunaliella cells, he is extracting their DNA and asking if the genes one type carries on its chromosomes are the same or different from the genes carried on the chromosomes of a different looking cell.

This is proving to be a very profitable and rewarding set of questions and answers. Professor Polle is already developing a database that he and others can then use to recognize different species of Dunaliella when they are discovered or collected. An additional benefit from this work is that it can now be used to extend the studies of biodiversity on this planet and how that diversity changes with human impact.

Collecting light for energy is something plants and Dunaliella do very well, and Professor Polle would like to know more about how they do it. One branch of his research is into the complex area of light-harvesting and what kinds of mechanisms, pigments and chemical reactions are necessary before a shaft of blue light can become part of a sugar molecule.

This is by no means an easy research question to ask or answer, particularly with Dunaliella, as these little cells don't respond well to stress. When their environment turns hostile, becoming too hot, for example, the cells respond by making large amounts of pro-vitamin A. This may be a natural reaction which protects the cells in some way from the effects of higher temperatures. But how do the cells do this?

Professor Polle is trying to find out why and how. The regulation of the genes that make pro-vitamin A is another area of research that could yield great economic rewards if Dunaliella is to be grown commercially. Professor Polle is looking for mutants in which the unstressed cell also over produces pro-vitamin A; mutants which could then be grown in normal conditions yet still make large amounts of this product for their growers.

Helping growers get commercial quantities of Dunaliella and their products to flourish in their ponds is yet another application of Professor Polle's research and one which might one day result in microalgal "farms."