Pilot‐plant process for the isolation of a microbial polysaccharide with a quaternary ammonium compound

Abstract

Abstract Microbial polysaccharides which have many potential industrial applications are receiving more and more attention. One of the economic obstacles to the commercialization of these polysaccharides has been the cost of isolating them from fermented broth. To reduce this cost a recycling process was developed. The polyanionic polysaccharide synthesized from glucose by the activity of the bacterium Xanthomonas campestris NRRL B‐1459 is precipitated from the fermented broth with a quaternary ammonium compound (QAC). QAC is removed from the precipitate with methanol leaving the water‐soluble polysaccharide. Evaporation of the methanol wash removed the methanol and substantially all the QAC was recovered in the concentrate. This was recycled for subsequent precipitations. Chemical assay and the viscosity of water solutions of the isolated polysaccharide indicate no adverse effects on it from recycled QAC. The cost to make this polysaccharide by the described procedure is estimated to be $1.14/lb. This cost estimate includes land, buildings, raw materials, equipment, labor and supervision, utilities, factory supplies, working capital, and plant overhead.