CCAC - Culture Collection of Algae at the University of Cologne: A new collection of axenic algae with emphasis on flagellates

The Culture Collection of Algae at the University of Cologne (CCAC) was formally established in spring 2001, when membership in the World Federation for Culture Collections was acquired (WDCM 807). However, the foundations of the collection were already laid in 1974, when microalgal cultures were first established from single cell isolates. Now approximately 1000 strains isolated from samples collected from diverse habitats and geographical regions are maintained in a research collection. From this collection a selection of axenic strains of algae has been transferred to CCAC. At present, 100 axenic cultures of selected strains of Bacillariophyceae, Chlorophyceae, Cryptophyceae, Dinophyceae, Euglenophyceae, Glaucocystophyceae, Haptophyceae, Mesostigniatophyceac, prasinophytes, Synurophyceae, Trebouxiophyceae and Zygnematophyceae are kept in CCAC. A strain list is included in the present paper. To increase the number of taxa in CCAC, purification of strains is performed continuously. For more robust cells, axenic cultures are obtained using well-established procedures such as washing with micro-capillaries, streak plating and spray plating on agar, if necessary in combination with low-intensity ultrasonication. However, for the purification of very small or delicate cells (in particular flagellates), fluorescence-activated cell sorting (FACS) has been the method of choice. FACS is routinely used for the purification of clonal/single cell-derived cultures, but promising results have also been obtained for one-step isolation and purification of algae from natural samples.