Microorganisms that produce exopolysaccharides have currently gained broad attention and are a subject of great concern for modern-day biotechnologists and microbiologists. Sphingomonas paucimobilis is a Gram-negative rod-shaped bacterium isolated from the Elodea plant tissue. The effect of the culture conditions on gellan gum production by recombinant S. paucimobilis ATCC 31461 in a stirred-type bioreactor was investigated. The products of fermentation were characterized by Fourier transform infrared (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The FTIR spectrum revealed characteristic peaks of different functional groups in the gellan. SEM was carried out to observe the morphology of the gellan gum, while the thermal stability of the biopolymer was determined by TGA and DSC analysis. The compositional analysis of the purified gellan showed that it is a heteropolymer containing glucose, rhamnose, and glucuronic acid. The compression test of the gellan revealed its textural property. Maximum gellan gum was attained after 48 h of incubation at 30°C with a pH of 6.5, 500 rpm, and 100% dissolved oxygen. The rheology study indicated the non-newtonian nature of gellan gum. The solubility of gellan gum in different polar and non-polar solvents was also investigated. The findings in this study showed that gellan gum produced by recombinant S. paucimobilis ATCC 31461 has a high potential to be utilized in the pharmaceutical and food industry.

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Gellan gum is an anionic polysaccharide produced by the bacterium Sphingomonas paucimobilis. Kaneko and Kang discovered the biopolymer in the laboratory of the Kelco Division of Merck and Co., California, USA. It is composed of tetrasaccharide repeating units of two residues of D-glucose, one of D-glucuronic and one of L-rhamnose. The functional properties of gellan gum make it one of the industrially useful exopolysaccharides. Sphingomonas paucimobilis ATCC 31461 is the bacterium used for the industrial production of gellan gum. The gellan gum has potential applications in food, pharmaceutical, biomedical and other industries. The gellan gum finds uses in the bioremediation field. Bioaugmentation of contaminated aquifers, biodegradation of hydrocarbons and the removal of dyes from wastewater are a few of its applications. This review provides an overview of the characteristics, production of gellan gum and recent bioremediation applications.