J. P. DUBACQ
Laboratoire des Biomembranes
Ecole Normale Superieure
U.R.A. C.N.R.S. 311 Rue d'Ulm
75230 PARIS Cedex 05, FRANCE
In recent years the production of algae in the world has reached more than 2 million tons. Algae are used either directly as total foodstuff (i.e. Spirulina) or as the source of products for the food industry (i.e polysaccharides) or more specific material to get coloured proteins. However many other compounds appear very interesting such as proteins, lipids, pigments, and others.
In order to improve the productivity of the algae culture we support the idea that much more fundamental research is now necessary to reach a biotechnological approach of these goal. The objectives of such research depend on the product that we want to improve. For total consumption, mass production appears to be the main purpose. For polysaccharides, the quality of the product is much more important and mass production is less emphasized. For the more specific products found in the algae, two ways are offered: the specific algae is grown only for that product, or the compound can be a by-product of another industrial processing. In any of these cases improvement of the productivity must be carefully followed in order to obtain the maximum quality of both the main products and by-products.
This brief paper focuses on several aspects of fundamental research on microalgae which are presently intended by a group of laboratories in France with the final purpose of a biotechnological transfer to industry. The three main lines of fundamental research that are investigated are the following:
Analytical research with accurate technics which reveal details of the chemical composition and can assume purity of the products. (An example will be given by the HPLC-diode array spectrophotometric analysis of pigments in Spirulina which reveals traces of rare carotenoids). A lot of interest has now turned to phycobiliproteins, not only as a source of protein food for a complementary diet like in Spirulina but also for medical and immunological utilization. In fact phycobiliproteins are parts of protein complexes which contain different proteins associated with pigments with different properties. One can see from an example that the organization of this complex is very complicated and consequently any biotechnological manipulation of this structure in order to get a more specific composition in phycocyanin or phycoerythrin requires much more work on the synthesis and assembly of this structure. Such research on physiology and genetic control are beginning now. On the other hand new and very interesting products can appear such as the lipid polymer resistant cell walls which will be described.
Physiological studies are classical in literature. They concern essentially the modifications of the productivity relative to environment factors. However it seems also improtant to underline that in some cases such modifications can result only in negligible changes in the composition and productivity. Much more specific physiological studies can be done to improve the production of a specific product by growing the algae with the addition of a low-cost substrate. (Assays of lipid synthesis in Spirulina or other cells will be given). Another possibility of alteration of the composition of algae comes from studies of the photosynthesis process and more specifically, photo-inhibition. During photoinhibition some changes in the carotenoids can occur due to protective oxidation. One could use such physiological processes to get a specific increase of one or another product.
Molecular biology concerns the studies of the genetic control of cell composition and metabolism. Up to now it is a scientific domain welldeveloped for higher plants where, in combination with biotechnology, it has resulted in very interesting progress in food production. For work on algae, this is far less developed although the knowledge of the cyanobacterial (blue-green algae) genome is more advanced. This type of science is just beginning for brown and red algae. It reveals very interesting possibilities for fundamental research as well as for future applied works. For example it shows essential differences from higher plants for the localization and regulation of the synthesis of chloroplast proteins. This might be of great importance for the manipulation of the phycobiliprotein composition of cells. This type of work must be developed.
These three main lines of fundamental research are developed at the same time as applied research; they promote each other as often as possible. Application by industry of results from fundamental research needs biotechnology and industrial transfer, which are necessary in order to promote a favourable situation for the discoveries from the type of research mentioned above.
Biotechnology is under development. Two specific lines of efforts are described here. The first consists of preparing protoplasts from brown algae. As anyone knows this step is very important in realizing a programme of genetic manipulation and introduction of foreign genes in a living organism. It has been a clue for the use of in vitro technics in higher plants. We hope that it will develop rapidly in algae and that it will open a new field of possibilities. The second one consists of a culture technology which aim to be as much controlled as possible. In that way, assays of algae incorporated into alginate are successful. They can promote some lipid productivity. Another technology for controlled culture is the tubular system, which gives a high yield.
Industrial transfer is now realized for the production of some substance such as pigments, and protein preparation the quality of which is guaranteed by the previous efforts of fundamental research. Constant productivity and composition is reached by this technique. It leads to the preparation of large quantities of pure products. (An example will be given for the large scale production of Porphyridium in tubular cultures with extraction of coloured products).
In conclusion, we hope that more research will be done in the near future and that the coordination of these efforts with industrial purpose will soon promote the use of algae -- the initial primary producer of organic compounds -- as one of the main biological resources in the world.
