Introduction:- In nature, cell wall polysaccharides fullfill a wide range of functions,eg

The cyanobacterial strain Phormidium tenue was subjected to different stress conditions like culture aging, phosphate and nitrate depleted condition, excess nitrate (10mM) and salinity (0.9M NaCl). Excess nitrate and salinity used were just the double amount, required for normal concentration. Growth was monitored by Chlorophyll content and total protein level in relation to polysaccharide production. Remarkable increase in EPS contents were noted in all stresses given, which were almost 1.7, 2, 3 and 4 times more in excess nitrate condition, phosphate depleted, nitrate depleted and high salinity respectively. It was also observed that aging is an important factor for increasing EPS production. Exocellular polysaccharide (EPS) from this marine cyanobacterium was characterized using GLCMS and stress induced variation in total production was studied in batch culture mode. The neutral sugar composition of Phormidium biomass was identified by gas liquid chromatography showing monosaccharide composition as Rhamnose, Fucose, Xylose, Mannose, Glucose and Galactose. It was evident from the study that the structural architecture of the extra cellular polysaccharide of Phormidium is highly complex in nature as common in algal system.