Pages: (20-43 )
Abstract
Xanthan gum [(C35H49O29)n] is a microbial exopolysaccharide which consists of pentasaccharide repeat units comprising of glucose, mannose, glucuronic acid and it is produced via fermentation by Xanthomonas sp. Xanthan gum is used as a thickening or stabilizing agent in the food, cosmetics, pharmaceutical and oil recovery industries. The xanthan gum imported to Nigeria are chemically synthesized which can be detrimental to living organisms hence, the need for local bio polysaccharides exploration that are safe and eco-friendly. Xanthomonas sp was isolated from dark rot leaves and surrounding soils of banana, mango and pear plants by tenfold serial dilution and pour plate method using Nutrient agar, semi selective media and yeast malt agar at 37 oC for 24 hours. The isolates were screened on carbon-enriched medium and characterised using standard techniques. Xanthan gum was produced by the isolates through submerged fermentation using sucrose at 37 oC for 72 hours. Ban2, RU 1, RU3, RU 4, SFL3, PEAR 4, SPEAR1 were isolated from the samples and Sfl2 had the highest viscosity of 33.00 mPa.s in the screening medium. The biochemical characterisation of the isolates indicated Gram’s negative short rods, catalase positive, oxidase negative and starch hydrolysis positive. Sfl2 had the highest yield of xanthan gum (21.1 g/L).
Keywords: Exopolysaccharide, Xanthan gum, Xanthomonas sp, fermentation.,