Cyanobacterium and green algae, LM

DIC light micrograph (LM) of Light micrograph of a cyanobacterium (Anabaena sp.) and the green algae: Netrium and Zygnema sp. Anabaena sp. is a filamentous cyanobacterium. It has specialized cells called heterocysts that have the ability to fix atmospheric nitrogen in soil. Anabaena spp. are therefore valuable to farmers since they increases soil fertility and crop yields. Netrium sp. is a type of green alga (chlorophyte, Chlorophyta) called a desmid. Most desmids are unicellular, with a single nucleus and one or more chloroplasts. The cell walls all have a inner layer rich in cellulose and an outer, thickened pectin layer. Zygnema sp. is a filamentous green alga (chlorophyte, Chlorophyta) that often forms pond scum, also called 'flab' (floating algae beds). Zygnema has 2 star-shaped chloroplasts. Magnification: x100 when shortest axis printed at 25 millimetres.