Functional carbohydrates from the red microalga Galdieria sulphuraria

Microalga could be a very good alternative to traditional agricultural crops, in the search for renewable resources. Microalgae show a high productivity and only need water, sunlight and carbon dioxide to grow. An additional advantage for the large-scale production is the fact that they do not require arable agricultural land and thus do not interfere with food production. The red microalga Galdieria sulphuraria is a member of the family of red algae, to which also red seaweeds belong. It is a very special species, as it grows best under very hot and very acid conditions. Red microalga naturally live in acid hot springs and geysers in areas with volcanic activity. What makes the Galdieria alga even more special is that it can grow just like plants in the light using photosynthesis to convert carbon dioxide into biomass; while in the dark it uses various organic compounds such as glycerol, a byproduct from biodiesel production, to grow. The flexible way of growing and the special living conditions at which the Galdieria alga thrives, make large-scale production relatively easy. Besides pigments that can be used as natural colorants, the Galdieria alga also produces two functional carbohydrates. One is a highly branched glycogen that can possibly be used in sports drinks or a specific kidney dialysis fluid. The other is floridoside, or galactosylglycerol, that is similar to a carbohydrate that is added to cosmetic products as a moisturizer. This PhD thesis describes the research into the production of these two functional carbohydrates and their properties.