ABSTRACT:
Over the past few decades, microbial exopolysaccharide have been invaluable ingredients in the food industry as well as in many attractive pharmaceutical and chemical applications. The biopolymer gellan is a more addition to the family of microbial polysaccharide that is gaining much importance due to its novel property of forming thermo-reversible gels when heated or cooled. Gellan gum is a water-soluble anionic polysaccharide produced by the bacterium Sphingomonas clodea. The gellan-producing bacterium was discovered and isolated by the former Kelco Division of Merck & Company in 1978 from the lily plant tissue a natural pond in Pennsylvania, USA. A polymer chain of gellan consists of tetrasaccharide repeating unit of L-rhamnose, D-glucose & D-glucoronate. Due to the unique structure and beneficial properties, gellan is currently described as a potent multifunctional additive for various pharmaceutical products. Specific gelling properties in different media led to the development of controlled release forms based on gellan. The native gellan is partially esterified with acyl substituents per repeat unit Gellan has unique characteristics & has many applications particularly in the food, pharmaceutical industry & biomedical fields.