title: Microbial production of levanase for specific hydrolysis of levan.
abstract: A newly isolated bacterial strain from Tunisian thermal source was selected for its ability to produce extracellular levanase when grown on levan substrate. The optimization of carbon source, nitrogen source, temperature and initial pH of the growth medium in submerged liquid cultures were investigated. In fact, levan was found to be a good inducer of levanase enzymes. The optimal temperature and pH of the levanase activity were 40 °C and 6.4, respectively. This enzyme exhibited a remarkable stability and retained 75% of its original activity at 55 °C for more than 1 h at pH 6.4. Crude enzyme of the strain rich in levanase was established for the hydrolysis of levan in order to produce fructooligosaccharides with variable degrees of polymerization which could be used in important fields such medicine, food-processing industry and cosmetic. The extracellular levanase of the strain was then, partially purified as determined by SDS-PAGE. The purification was achieved by ammonium sulfate precipitation, gel filtration and DEAE cellulose chromatographies.
authors.affiliation: Biochemistry Laboratory, Department of Life Science, Faculty of Science, University of Sfax, PB 802, 3018 Sfax, Tunisia. imenbiologie@yahoo.fr
authors.forename: Imen
authors.initials: I
authors.lastname: Dahech
authors.forename: Hanen
authors.initials: H
authors.lastname: Ben Ayed
authors.forename: Karima Srih
authors.initials: KS
authors.lastname: Belghith
authors.forename: Hafedh
authors.initials: H
authors.lastname: Belghith
authors.forename: Hafedh
authors.initials: H
authors.lastname: Mejdoub
mesh_terms: D001419:Bacteria / Q000201:enzymology* / Q000254:growth & development; D002244:Carbon / Q000378:metabolism; D003902:Detergents; D004789:Enzyme Activation; D005630:Fructans / Q000378:metabolism*; D006026:Glycoside Hydrolases / Q000302:isolation & purification / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007477:Ions; D008670:Metals; D009584:Nitrogen / Q000378:metabolism; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D003902:Detergents; D005630:Fructans; D007477:Ions; D008670:Metals; D002244:Carbon; C072599:levan; D006026:Glycoside Hydrolases; C021512:levanase; D009584:Nitrogen
keywords: Fructooligosaccharides; Levanase; Purification