Growth and accumulation of polysaccharide by Xanthomonas campestris

✍ Scribed by Dr. U. Behrens; M. Klima; S. Fiedler

• Book ID: 102389466
• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 252 KB
• Volume: 20
• Category: Article
• ISSN: 0233-111X
• DOI: 10.1002/jobm.19800200307

✦ Synopsis

The synthesis of bacterial exopolysaccharides is favoured by a high carbon : nitrogen ratio and generally stimulated by nitrogen limitation (SUTHERLAND 1972). For xanthan accumulation with Xanthomonas campestris in a medium containing both yeast extract and nitrate as nitrogen sources, BEHRENS et at. (1977) found diauxic growth. Separated by a transition period, the first period with logarithmic growth is followed by a second in which accumulation of the exopolysaccharide occurs. The authors proposed nonbalanced growth as one essential condition for xanthan overproduction. We investigated whether diauxic growth is caused by the mixed nitrogen source, and attempted to elucidate the influence of growth on xanthan accumulation.

Fermentation: Strain and methods of cultivation were the same as described previously with the exception of the nitrogen source (BEHRENS et al. 1977). Instead of a mixture of nitrate and yeast extract, nitrate or peptone alone were used.

Analytical: Bacterial cells were counted. The bacterial mass was determined gravimetrically and by optical-density measurements as described previously (BEHRENS et al. 1977). Peptone and