Optimization and Standardization of Cyst Formation in Azospirillum

The objective of the study was to determine the most suitable cyst forming media in liquid conditions. Encystation in Azospirillum brasilense Cd was observed by using routine laboratory staining and microscopy. Best encystment occurred in liquid or semisolid media containing fructose (8 mM) and KNO3(0.5 mM). The encysted forms consisted of a central body filled with poly-β -hydroxybutyric acid granules, an electrontransparent intine like region,and a thick outer layer. The polymer content of the cells increased sharply and reached maximum on the 2 day of growth followed by a gradual decline as the culture aged. Further they were subjected to heat treatment and stained to verify that these are cysts.