Colonial variation in Xanthomonas campestris NRRL B-1459 and characterization of the polysaccharide from a variant strain

Abstract

Stock cultures of Xanthomonas campestris NRRL B-1459 require special attention to maintenance and propagation to assure consistent production in good yields of the extracellular polysaccharide xanthan. Under customary conditions of propagative maintenance on agar slants, variant colony types develop that are smaller in size than the normal type. The rate of regression of the normal to the variant forms was diminished when the D-glucose content of the stock medium was sufficient to avoid depletion during storage and when transfer to fresh medium was reduced to 14-day intervals. Under conditions for polysaccharide production, the normal large-colony type gives crude culture liquors after 48 h of 7000 centipoise (cp) viscosity; the predominant variant form gives only 4000 cp. On the basis of 2.1% initial D-glucose, biopolymer yields for the normal and variant strains were 62 and 43%, respectively. Polysaccharide produced by the variant (small-colony type) differs adversely in solution properties from that of the parent strain (large-colony type); it differs also in its lower content of pyruvic acid and O-acetyl substituents. The molar ratios of constituent sugars (D-glucose, D-mannose, and D-glucuronic acid), however, were identical in polysaccharides with the normal and variant strains. Exclusion of colonial variants from fermentations is prerequisite to production of xanthan optimum in properties and yield.

Xanthan Induces Plant Susceptibility by Suppressing Callose Deposition

“…Xcc strains 8004 (wild type), 8397 (gum::Tn5lac; EPS minus), and 8396 (gum::Tn5lac; truncated EPS ) were described previously (Cadmus et al, 1976;Daniels et al, 1984;Tang et al, 1991;Slater et al, 2000) and characterized (Vojnov et al, , 2002. Xcc strains were cultured in a 28°C shaker in PYM medium as reported by Cadmus and collaborators (1976).…”

“…Bacterial suspensions (OD 600 5 0.05) were prepared from 24 h/28°C PYM-liquid Xcc cultures (Cadmus et al, 1976) with 10 mM MgCl 2 , and Silwet L-77 was added (200 mL/L). Plant pots (nine seedlings each) were submerged upside down in the bacterial solution for 30 s and then covered with a transparent lid.…”

Rheological Properties of Deacetylated Xanthan in Aqueous Media

“…About one-half or one-third of the terminal mannose residues bear a pyruvic acid, depending on the culture conditions. 7 ) The acetyl residues of xanthan have been suggested to contribute to its intramolecular association,S) though this has not been discussed with regard to its rheological properties. Deacetylation can be done without further modification of the polymeric structure by mild alkaline treatment.…”

Effect of virulence and serial transfers of Xanthomonas campestris on xanthan gum production

“…A problem arising in screening microorganisms for polysaccharide production is the lack of suitable techniques for selection of potential strains. Cadmus et al (1) reported that some morphological characteristics of colonies of Xanthomonas could be correlated with polymer production and pyruvic acid content. Kidby et al (4) found that small colony variants produce gums of lower quality whereas large colonies produce higher quality gums; virulence and infrared spectra of polymers and penicillin G sensitivity were also suggested (7,12).…”