OPTIMAL CONDITIONS OF LEVAN AND FRUCTOOLIGOSACCHARIDES PRODUCTION BY A NEWLY ISOLATED THERMOPHILIC BACTERIUM
Hafedh Mejdoub, Dahech, I., Belguith, H. and Belghuith, K.
Science Faculty of Sfax, University of Sfax, Tunisia
Abstract: Levan and fructooligosaccharides had several applications in the domain of medicine, cosmetic, agroalimentary, pharmacia. In this work we investigate the production of levan and fructooligosaccharides by a newly isolated thermophilic bacterium and the synthesis of levan by levansucrase at high temperature. This bacterium was identified as being Bacillus sp. The best nitrogen and carbon source that permitted good enzyme production were sodium nitrate with yeast extract and sucrose correspondingly. The optimal temperature and pH of culture was 50°C and 6.5 respectively. The levansucrase activity was very thermostable since it lost only 30% after one hour of incubation at 90°C. Oligosaccharides (fructooligosaccharides) were obtained by acidic hydrolysis of levan produced by this bacterium or by enzymatic way, while acting on times of synthesis and/on sucrose concentrations used, finally by hydrolysis of levan. Determination of the polymer content was done through RMN analysis, which indicates that we have a fructose polymer. This result was confirmed by CCM analysis after a total hydrolysis of the polysaccharide.
Keywords: Levan, fructooligosaccharides, thermophilic bacterium, enzyme and production.