Cyanobacterium (Anabaena sp.), SEM

Coloured scanning electron micrograph (SEM) of Anabaena sp., Gram-negative, oxygenic, photosynthetic, nitrogen fixing, filamentous cyanobacterium (prokaryote). Note the larger cells in the filament called heterocysts which are involved in nitrogen fixation. Anabaena is a genus of filamentous cyanobacteria (formerly known as blue, Green algae). It found as planktonic cyanobacterium (all types of water) and is known for its nitrogen fixing abilities. Blooms or massive growths can occur in waters with a lot of nutrients. These blooms discolour the water and give it a bad odour when the cells die and decay. Anabaena is one of four genera of cyanobacteria that produce neurotoxins. These toxins are harmful to local wildlife, as well as farm animals and pets. Production of these neurotoxins is part of its symbiotic relationships it forms with certain plants. Some species of Anabaena are endophytes. Magnification: x660 when shortest axis printed at 25