Formation, sedimentation and germination properties of Anabaena akinetes

The formation and sedimentation of akinetes of Anabaena cylindrica were analyzed quantitatively to identify practical strategies for removing or harvesting akinetes. The critical iron concentration for development of vegetative cells of this cyanobacterium into akinetes was between 0.060 0.240 mg/l. Before germination, approximately 10% of the total akinetes that were formed in trichomes settled down, being separated from the floating algal mat on the water surface. The effects of drying processes, which are inevitably involved in the production of biofertilizers, on the germination ability of the akinetes were also examined. Akinetes demonstrated tolerance against severe drying processes, i.e., heat-drying in an oven at 60 degreesC for 50 h and drying under sunlight for 10 h, suggesting that they can be used as a biofertilizer after drying processes. It was also shown that dried akinetes can be stored in a dried state for at least several weeks. (C) 2002 Elsevier Science B.V. All rights reserved.