某些乳杆菌属细菌所产胞外多糖具有一些重要的益生功能.本研究优化菌株Lactobacillus plantarum-12培养基碳源、培养温度和时间,以增加该菌株胞外多糖表达量,并通过细胞增殖检测试剂盒(MTS Cell Proliferation Colorimetric Assay Kit,MTS)和末端脱氧核苷酸转移酶介导的dUTP缺口末端标记测定法(Terminal deoxynucleotidyl-transferase mediated dUTP nick end labeling,TUNEL)研究其胞外多糖对HT-29细胞增殖的抑制作用以及诱导细胞凋亡作用,并研究胞外多糖清除DPPH自由基的能力以评价其潜在的抗氧化能力.结果表明,乳杆菌菌株生物合成EPS最佳条件为:MRS培养基中碳源为40 g/L蔗糖、培养温度30℃、培养时间48 h时,L.plantarum-12 EPS产量为50 mg/L;随着胞外多糖(Exopolysaccharides,EPS)作用浓度的增加,对HT-29细胞的抑制率增大,当EPS浓度为500 μg/mL时HT-29细胞凋亡数可达50.3个,显著高于其它3个浓度(p<0.05);L.plantarum-12 EPS的DPPH自由基清除率也随EPS作用浓度的增加而增大,在0.5 mg/mL时高达49.13 %.L.plantarum-12 EPS的分子结构及其益生功能还有待进一步研究.%Exopolysaccharides(EPS)produced by some Lactobacillus bacteria have some important probiotic function. In this study, the carbon source, culture temperature and time of Lactobacillus plantarum-12 were optimized to increase the production of EPS;the effects of EPS on the proliferation and apoptosis of HT-29 cells were studied by MTS method and TUNEL method, and the DPPH radical scavenging ability of the EPS was studied to evaluate its potential antioxidant capacity.The results showed that the L.plantarum-12 EPS yield was up to 50 mg/L when the strain was cultured in MRS medium with sucrose as carbon source at the concentration of 40 g/L,at 30℃for 48 h;the survival rate of the HT-29 cells treated by L.plantarum-12 EPS decreased with the increase of the EPS concentration;when the EPS was at 500 μg/mL,the number of apoptotic HT-29 cells reached 50.3,significantly higher than those of the other groups(p<0.05);the DPPH radical scavenging rate of L. plantarum-12 EPS also increased with the increase of EPS concentration, up to 49.13 % at 0.5 mg/mL. However, the molecular structure of L. plantarum-12 EPS and its probiotic function remain to be further studied.
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