413 Bulletin UASVM Animal Science and Biotechnologies, 66 (1-2)/2009 Print ISSN 1843-5262; Electronic ISSN 1843-536X The Influence of Carbon Source and of the Conditions for Fermentation on the Production of Exopolysaccharides Emanuel VAMANU 1,2 , Adrian VAMANU 1,2 , Diana SMARANDACHE 3 , Ovidiu POPA 1,2 , Narcisa BĂBEANU 1 , Sultana NIłĂ 4 , Florin MARIN 1 , GheorgiŃă DANCIU 1 1 University of Agronomic Sciences and Veterinary Medicine, Faculty of Biotechnology, 59 Mărăşti Bv, Bucharest, Romania; email@emanuelvamanu.ro 2 Applied Biochemistry and Biotechnology Center–Biotehnol, 59 Mărăşti Bv, Bucharest, Romania; 3 University of Bucharest, Faculty of Biology, 91-95 Spl. IndependenŃei, Bucharest, Romania; 4 National Institute of Chemical-Pharmaceutical Research-Development–ICCF Bucharest, 112 Vitan Road, Bucharest, Romania Abstract. The synthesis of exopolysaccharides was determined for the strains Lactobacillus sp. IL1, Lactobacillus sp. IL4 in MRS medium having glucose, lactose and sucrose as carbon sources. From the results obtained it was highlighted the fact that, by using sucrose as carbon source, the biggest quantity of exopolysaccharides is obtained, namely 41 mg/L and, respectively, 74 mg/L. The influence of different concentrations of sucrose (5, 10, 15, 20%) on the production of exopolysaccharides was tested. It resulted that for a concentration of 15% sucrose, a maximum of the quantity of synthesized exopolysaccharides is obtained. Also, the influence of temperature and pH on the capacity to synthesized exopolysaccharides for the used strains was tested. From the determinations made it resulted that a temperature of 37 0 C and a pH of 7 represent the ideal parameters so as to obtain a maximum quantity of exopolysaccharides, in the case of using MRS with 15% sucrose. 55 mg/L are obtained, for the strain Lactobacillus sp. IL1 and 145 mg/L, for the strain Lactobacillus sp. IL4. Keywords: Lactobacillus, exopolysaccharides, sucrose INTRODUCTION Lactic bacteria from Lactobacillus type are frequently used in alimentary fermentations due to their ability to improve the organoleptic characteristics of food. They are also used due to the conservation capacity of some perishable raw materials, meat and vegetables. These bacteria are capable to normally produce quantities of exopolysaccharides of approximately 150 – 200 mg/l [1]. The strains of lactic bacteria synthesize two types of exopolysaccharides: homopolysacharides and heteropolysacharides. In the case of homopolysacharides, there is a glucide, which repeats, and for heteropolysacharides different monoglucides repeat. A special importance is granted to homopolysaccharides that contain fructose. This is due to the fact that it acts like a prebiotic compared to other microbial strains [2]. Some exopolysaccharides produced by the strains of lactic bacteria have an important role in the stimulation of the immune system, the decrease of the cholesterol level or against ulcer [3]. The polysaccharides produced by the strains of lactic bacteria have an important role in alimentation as thickening, jellification agents or water-binding agents. [4] Also, the effect of their synthesis is the increase of the rheologic properties of food. Besides all these, the role