Caracterização de biopolímeros produzidos por Beijerinckia sp. 7070 em diferentes tempos de cultivo

Abstract

Biopolymers are microbial polysaccharides. The biopolymer produced by Beijerinckia sp 7070 has pseudoplastic behaviour and shows high viscosity at low deformation rates, giving to polymer excellent suspension characteristics. The objective of this work was to characterize the biopolymer produced at different culture times by Beijerinckia sp 7070 in relation to total production, production of short and long fiber polymers, productivity, viscosity and chemical composition. The polymers produced in liquid YM medium were recovered at different culture times, dried and weighted for determination of the production and productivity. Fiber type produced during the culture times was evaluated microscopically. Apparent viscosities of the 1% (w/v) aqueous solutions were determined at 6, 12, 30 and 60rpm, at 25º C, in a Brookfield viscosimeter. Biopolymer composition was determined by comparative thin layer chromatography. The highest total biopolymer productions was found at 30 and 72h, the highest productivity was at 48h and the highest viscosity was at 72h. The long fiber polymer showed a tendency of becoming longer with time. The viscosity of long fiber polymer was higher than the short fiber one. All polymers showed the same components (glucose, galactose, fucose and glucuronic acid) but at different concentrations.