CONTINUOUS CULTURE SYSTEM FOR PRODUCTION OF BIOPOLYMER LEVAN USING ERWINIA-HERBICOLA

The optimal production of the fructan biopolymer levan by the bacterium Erwinia herbicola was investigated, including variations in nitrogen, carbon and phosphorous sources, pH, incubation time, culture methodology, and polymer processing. Levan yields up to 19% by weight were produced based on conversion of sucrose as the carbon source when grown in a continuous culture system and processed by tangential flow filtration. Product identity was confirmed with gas chromatography (GC) and C-13 nuclear magnetic resonance (NMR). Gel permeation chromatography (GPC) and low-angle laser light scattering (LALLS) determination of the molecular weight of the product showed a significant difference in molecular weight values dependent on the method of analysis. Analysis by GPC resulted in a molecular weight one order of magnitude lower than LALLS independent of sample, underscoring the unusual nature of this biopolymer.