Title
Effects of culture medium composition on biosynthesis of exopolysaccharides
Authors
ANCA ROXANA PETROVICI IRINA ROSCA GIANINA DODI ALINA NICOLESCU MIHAELA AVADANEI CRISTIAN DRAGOS VARGANICI and DIANA CIOLACU

Received In memory of Acad. Cristofor I. Simionescu, for his contributions to the chemistry of cellulose and the creation of this journal
Published Volume 51 Issue 9-10 September-December
Keywords lactic acid bacteria, exopolysaccharide, GPC, TGA/DSC, FTIR, NMR

Abstract
The study investigated the influence of culture medium composition on the amount and structure of exopolysaccharides produced by the fermentation of lactic acid bacteria. It was established that the most favorable culture medium composition was the standard MRS prepared in milk supplemented with sucrose. Dynamic conditions were found more suitable for the biosynthesis of exopolysaccharides. An amount of 9 g dry polymer/L of culture medium was obtained. Gel permeation chromatography highlighted the presence of multiple exopolysaccharide fractions, mainly with a low degree of heterogeneity. FTIR, 1H and 13C-NMR analyses showed that dextran was the main biosynthesis product. The thermal stability of the obtained biopolymers was determined by TGA and DSC analyses. Both methods indicated a pure and stable polymer, comparable with dextran.