乳酸菌胞外多糖的生物合成和结构特性

Biosynthesis and Structural Properties of Extracellular Polysaccharides Produced by Lactic Acid Bacteria

微生物可分泌多糖于细胞表面形成荚膜多糖、或分泌多糖于细胞周边培养基中形成粘液多糖。乳酸菌产胞外多糖在发酵乳的流变学特性、产品的结构和质地以及口感等方面起到重要作用。有的胞外多糖还具有抗癌、抗溃疡、免疫调节或降胆固醇等活性。近十年来，有关乳酸菌胞外多糖生物合成的分子生物学、生物化学、多糖的化学分析和结构特性等方面是乳品科学研究的一个热点。本文拟着重讨论乳酸菌产胞外多糖基因簇的结构和功能、多糖的生物合成和结构特性。

Micro-organisms may produce polysaccharides on the cell surface to form capsules, or secrete into their surrounding medium to form extracellular polysaccharides. Production of exopolysaccharides by lactic acid bacteria plays an important role in the theological properties, consistency and texture, as well as the mouthfeel of the products. Some exopolysaccharides may be biologically active against cancers and ulcer, with immunomodulating and cholesterol lowering activity. In the last 10 years, studies on the molecular biology of biosynthesis, biochemistry and chemical structure of exopolysaccharides produced by lactic acid bacteria have gained considerable interest in dairy research. The present paper focuses on discussion of the structure and function of the gene clusters related to exopolysaccharide biosynthesis, mechanism of biosynthesis and molecular structure of the exopolysaccharides produced by lactic acid bacteria.