Introduction Phycocyanin(PC) is a blue photopigment used for many applications, for example as a natural food colorant in the food industry (e.g. M&M and Gatorade). This pigment is produced by a natural mutant of the red microalgae G. Sulphuraria (strain 074G). This kind of algae can grow in various situations. It can produce in the dark, on various organic compounds and at various Ph. values. Phycocyanin is found only in cyanobacteria, Cryptophyceae and Rhodophyceae, is among the most important substances produced uniquely in cyanobacterial and microalgae cultures. The commercial production of PC is done in phototrophic cultures of the cyanobacterium Spirulina plantensis. The energy source for this is sunlight. Because these cultures depend on the sunlight, or externally supplied light it is very hard to scale up these cultures without losing productivity. This is because the surface area to volume ratio decreases at increasing scale and the light paths inside the cultures get longer. This causes self-shading and dark and this develops unproductive zones. (Eriksen J. K., 2005) The algae Galdieria Sulphuraria, can grow photo-, mixo and heterotrophically in warm acidic springs and can still produce PC. As told before the strain 047 G of G. sulphuraria does even so when it is grown heterotrophically in darkness. (Schnarrenberger, 1995) High rates of biomass which is possible in high-cell-density fed-batch cultures of G. sulphuraria 074G compensates for the relative low PC concentration in the algae; 3-4 mg g-1 of biomass dry weight in comparison to the phototrophic Spirulina platensis; 60-74 mg g-1 dry weight. Altough there is a big difference between the amount of PC per cell the total production of G. Sulphuraria 074G is 1.7-13.6 times higher than the rate of PC production found in outdoor S. platensis cultures. (Materassi, 1997) Following those findings we are going to look whether the production of PC by G. Sulphuraria 074G is applicable and profitable for commercial use. Also we’re going to look at what is the best way to produce PC. Methods Starting the project we had some trouble with our group members. At first the group only consisted of two group members, Coen and Bart. After two weeks Simon joined the group and then we we’re with three members. Coen and Bart already made a small start. Just after Simon joined Coen had to quit the study because of the lack of ECT’s so we were left with only two people. This caused a lot of trouble at first because Simon hadn’t spoken to professor van der Maarel and therefore Bart needed to introduce him to the project. After that we decided to divide the parts, but we kept a good communication about the progress of each other. Because we were with only two people it was easy to keep good communication and clarity about who was doing what. At the end we sat down together to put everything together and hand in the project. Theory Common Back Ground Information The current production of Phycocyanin is mostly done by light dependant micro-organisms. But this harvest itself is very low. This is because they depend on light, because light is a really hard variable to control it is really hard to get optimal production. When producing Phycocyanin with this light dependant micro-organism which is called Spirulina Platensis there are some other problems occurring. The amount of surface area is very low, because it is really hard to get as much surface in the light as possible. This means it is really hard to scale up the process of producing Phycocyanin. As an alternative of this there is an heterotrophic algae, called Galdieria Sulphuraria. This type of algae is able to live in extreme surroundings which have a lot of positive points. By a natural mutation of this algae on the strain 074G it is possible for it to produce Phycocyanin. For the sake of this paper we regard the production of Phycocyanin inside the algae as a black box and look at the production optimisation in a reactor instead of the biotechnological production of the Phycocyanin. As stated before, Galdieria Sulphuraria is able to survive in extreme surroundings. It can live at very acid locations with a ph of 1 and it does not need sunlight. Because Galdieria Sulphuraria does not need sunlight it needs an energy substitute for producing Phycocyanin. The energy source most used to function as energy source is suger (glucose/fructose) and this causes a decent output of Phycocyanin. Applications In this report the main focus is how to optimize the production of Phycocyanin in large quantities using the algae Galdieria Sulphuraria. Phycocyanin has a very broad range of applications which will be discussed in the following paragraph. The most common use of Phycocyanin is as a colourant in a diverse range of foods and drinks, think of blue M&M’s and blue Gatorade. Phycocyanin has a lovely deep light blue colour which enhances the looks of foods it’s processed in. Besides a merely cosmetic fun