International Journal of Scientific Engineering and Applied Science (IJSEAS) - Volume-1, Issue-6, September 2015 ISSN: 2395-3470 www.ijseas.com 476 Optimization and characterization of dextransucrase production by local Leuconostoc mesenteroides Asmaa Sabah Al-doori* Aswan Hamdullah Aboud* Ziad TariQ Sedrah** *Baghdad university/College of Agriculture/Food Science Dep. ** Diyala university/College of Agriculture/Food Science Dep. Abstract The dextransucrase production by local Leuconostoc mesenteroides was optimized and characterized to reach the optimum conditions of producing this enzyme which used in many food applications such as dextran production. The optimum conditions were using sugar as a carbon source with 20% concentration for giving the highest specific activity of dextransucrase, yeast extract as a nitrogen source, 25⁰C as incubation temperature,6.5 optimum production pH and 10 6 inoculum size. The crude enzyme was characterized for pH stability and heat stability, they were 4-5 and 30⁰C for an hour, respectively. The enzyme was purified by using sephadex G-100 with a fold of 4.56 and overall yield of 20.5% of activity, then precipitate by ethanol with a fold of 17.88 and overall yield of 20.64% of activity. Key Words: Dextransucrase, Leuconostoc mesenteroides, Optimization, Characterization. Introduction Dextransucrase (E. C. 2.4.1.5) from Leuconostoc species are used in industry for the production of oligosaccharides and dextran. Because of their desirable physiochemical properties in food and their prebiotics effect on intestinal bacteria, these oligosaccharides are very useful as food additives. Oligosaccharides produced by dextransucrase find several applications in food, feed, pharmaceutical, or cosmetic industries (5). Dextranucrase (glucansucrase or glucosyltranferase) is an extracellular enzyme that synthesizes dextran from sucrose (3). Many authors have described the effects of sucrose concentration, aeration rate, agitation speed, medium pH, incubation temperature, nature of the yeast extract and other nutritional requirements on the production of dextransucrase, dextran and fructose from sucrose using different strains of Leuconostoc mesenteroides (3,5). This enzyme is produced by many varieties of lactic acid bacteria, Leuconostoc and Streptococcus (6) Pediococcus, another lactic acid bacterium may also produce dextransucrase (9). Many authors purified this enzyme by different methods, The results confirmed the multimeric entity of this enzyme, which remains in single molecular form in the native state and separates into multiple bands when denatured by boiling, SDS or 2-mercaptoethanol (8). The aim of this study is to optimize the growth conditions for dextransucrase production by a local isolate of Leuconostoc mesenteroides from fermented cabbage.