Lactic acid bacteria are fully recognized for their industrial applications among which the production and release of exopolysaccharides. In the present investigation, we screened fifteen Lactobacilli in order to find ropy strains, quantify exopolysaccharides and detect proteins specifically associated with the ropy-exopolysaccharide production. The highest ropy-exopolysaccharide producer (L. helveticus 6E8), was grown in stimulating and basal condition (10% and 2% lactose) and subjected to comparative proteomic analysis. The levels of 4 proteins were found significantly increased in the membrane fraction under stimulating conditions: a specific exopolysaccharide biosynthetic protein, a stress-induced protein, a protein involved in secretion and an ATP-synthase subunit. Conversely, several enzymes involved in anabolism and protein synthesis were decreased. These results suggest a general shift from growth to exopolysaccharide-mediated protection from the hyperosmotic environment. Due to the great interest in exopolysaccharides with novel features, the identification of these proteins could have implications for future improvements of industrial strains.

乳酸菌因其工业应用而得到充分认可，其中胞外多糖的产生和释放。在本研究中，我们筛选了15株乳酸杆菌，以发现罂粟菌株，定量胞外多糖并检测与该多糖相关的蛋白质。最高的ropy-外多糖生产者（L. helveticus6E8）在刺激和基础条件下生长（10％和2％乳糖），并进行比较蛋白质组学分析。在刺激条件下，发现膜部分中的4种蛋白质水平显着增加：一种特定的胞外多糖生物合成蛋白，一种应激诱导蛋白，一种参与分泌的蛋白和一个ATP合酶亚基。相反，参与合成代谢和蛋白质合成的几种酶减少了。这些结果表明，从高渗环境到生长由胞外多糖介导的保护已普遍转变。由于对具有新颖特征的胞外多糖的极大兴趣，这些蛋白质的鉴定可能对工业菌株的未来改进有影响。