Xanthan Biopolymer Semipilot Fermentation

Abstract

Using standard microbiological techniques in a semi pilot plant-scalable fermenter, xanthan-specific culture techniques developed by the U.S. Dept of Agriculture's Northern Regional Research Laboratory (NRRL) were used at Marathon Oil Co.'s Denver Research Center (DRC) to obtain improved and reproducible high conversions and yields of xanthan biopolymer broth. Practical nutrients and fermenter parameters were studied to define and improve the viscosity performance and economics of xanthan broth production for thickening water in the Marafiood™ enhanced oil recovery process.

Mixing in the Fermentation and Cell Culture Industries

“…Xanthan gum is an extracellular polysaccharide produced by Xanthomonas campestris and is commercially the most important bacterial polysaccharide. It has widespread applications as a viscosity-enhancing agent and stabilizer in the food, pharmaceutical, and petrochemical industries (Jeanes et al, 1976;Norton et al, 1981). Since the cost of downstream processing determines whether or not the manufacture of the gum is commercially feasible, a high product concentration (>25 g/L) is essential (Pace and Righelato, 1980;Galindo, 1994).…”

Reproducibility of Pilot Scale Xanthan Fermentations

“…Since the end application of the gum is mainly dependent on this parameter (Suh et al, 1988), it is also desirable to obtain reproducible gum rheological characteristics. Inconsistency of results in Xanthan fermentations have been reported by Norton et al (1981). These authors used a complex medium and performed five replicate experiments with both inocula grown from agar slopes as well as from the paper strip technique recommended by Jeanes et al (1976).…”

“…Strain Instability. There are several reports in the literature regarding the genetic instability of X. campestris (Silman and Rogovin, 1972;Cadmus et al 1976;Jeanes et al, 1976;Kidby et al, 1977;Norton et al, 1981). Jeanes et al (1976) and Kidby et al (1977) stated that repeated culturing of X. campestris was unsuitable for maintaining the desired genetic characteristics.…”

“…Xanthan gum is an extracellular polysaccharide produced by Xanthomonas campestris. It has widespread commercial applications as a viscosity enhancing agent and stabilizer in the food pharmaceutical and petrochemical industries Norton et al, 1981). During the course of the fermentation, the excretion of the polysaccharide results in a highly viscous and shear thinning broth.…”