Zhou J S, Gopal P K, Gill H S
Milk and Health Research Centre, Institute of Food, Nutrition and Human Health, Massey University, Palmerston North, New Zealand.
Int J Food Microbiol. 2001 Jan 22;63(1-2):81-90. doi: 10.1016/s0168-1605(00)00398-6.
The mucus layer (mucin) coating the surface of the gastrointestinal tract (GIT) plays an important role in the mucosal barrier system. Any damage or disturbance of this mucin layer will compromise the host's mucosal defence function. In the present study, the ability of three potential probiotic lactic acid bacteria (LAB) strains (Lactobacillus rhamnosus HN001, Lactobacillus acidophilus HN017, Bifidobacterium lactis HN019) to degrade mucin in vitro was evaluated, in order to assess their potential pathogenicity and local toxicity. The LAB strains were incubated in medium containing hog gastric mucin (HGM, 0.3%) at 37 degrees C for 48 h, following which any decrease in carbohydrate and protein concentration in the ethanol-precipitated portion of the culture medium was determined, using phenol-sulphuric acid and bicinchonic acid (BCA) protein assays, respectively. The change in molecular weight of mucin glycoproteins, following incubation with the test strains, was monitored by SDS-polyacrylamide gel electrophoresis (SDS-PAGE). In order to expose any ability of the test strains to degrade mucin visually and more directly, the test strains were also cultured on agarose containing 0.3% HGM and incubated anaerobically for 72 h at 37 degrees C. No significant change in the carbohydrate or protein concentration in mucin substrates was found following incubation with the test strains. No mucin fragments were derived from the mucin suspension incubated with test strains, and no mucinolysis zone was identified on agarose. These results demonstrate that the potential probiotic LAB strains tested here were unable to degrade gastrointestinal mucin in vitro, which suggests that these novel probiotic candidates are likely to be non-invasive and non-toxic at the mucosal interface.
覆盖在胃肠道（GIT）表面的黏液层（黏蛋白）在黏膜屏障系统中发挥着重要作用。该黏蛋白层的任何损伤或干扰都会损害宿主的黏膜防御功能。在本研究中，评估了三种潜在的益生菌乳酸菌（LAB）菌株（鼠李糖乳杆菌HN001、嗜酸乳杆菌HN017、双歧杆菌HN019）在体外降解黏蛋白的能力，以评估它们的潜在致病性和局部毒性。将LAB菌株在含有猪胃黏蛋白（HGM，0.3%）的培养基中于37℃孵育48小时，之后分别使用苯酚 - 硫酸法和二辛可宁酸（BCA）蛋白测定法测定培养基乙醇沉淀部分中碳水化合物和蛋白质浓度的任何降低情况。通过十二烷基硫酸钠 - 聚丙烯酰胺凝胶电泳（SDS - PAGE）监测与测试菌株孵育后黏蛋白糖蛋白分子量的变化。为了更直观、更直接地揭示测试菌株降解黏蛋白的能力，还将测试菌株在含有0.3% HGM的琼脂糖上培养，并于37℃厌氧孵育72小时。与测试菌株孵育后，未发现黏蛋白底物中碳水化合物或蛋白质浓度有显著变化。与测试菌株孵育的黏蛋白悬浮液未产生黏蛋白片段，并且在琼脂糖上未鉴定出黏蛋白溶解区。这些结果表明，此处测试的潜在益生菌LAB菌株在体外无法降解胃肠道黏蛋白，这表明这些新型益生菌候选菌株在黏膜界面可能是非侵入性且无毒的。
