属特异性T-RFLP技术在双歧杆菌群落分析中的应用

【目的】以双歧杆菌标准菌株为材料,构建双歧杆菌属特异性末端限制性片段长度多态性分析(T-RFLP)技术,用于微生物群落中双歧杆菌的特异性分析。【方法】采用16S rRNA基因的双歧杆菌属特异性引物,5′-端用HEX荧光标记,结合通用引物1510r进行双歧杆菌特异性PCR扩增,软件模拟酶切后选取Hae III和Alu I进行限制性酶切,对酶切消化产物的荧光标记末端测序得到T-RFLP峰谱图。同时将该技术与实验室已建立的乳酸杆菌属特异性T-RFLP技术相结合,建立多相T-RFLP技术应用于对市面上益生菌产品的时效性检测。【结果】建立的方法能够快速准确地对不同种的双歧杆菌及合生元产品中的益生菌进行定性或半定量分析。【结论】据此,成功搭建T-RFLP技术用于微生态环境中双歧杆菌的检测,并成功将多相T-RFLP技术用于市售益生菌产品的时效性检测。     

In vitro and in vivo evaluation of the prebiotic activity of water-soluble blueberry extracts

The prebiotic effects of water extracts of two blueberry (BBE) cultivars (‘Centurion’ and ‘Maru’) were studied using pure and mixed cultures of human faecal bacteria. The results demonstrated for the first time that addition of BBE from both cultivars to broth media containing pure cultures of Lactobacillus rhamnosus and Bifidobacterium breve resulted in a significant increase (P < 0.05–0.0001) in the population size of these strains. Batch fermentation system was used to monitor the effect of BBE addition on the mixed faecal bacterial populations (obtained from healthy human donors). Addition of BBE from both cultivars to batch cultures inoculated with mixed human faecal cultures resulted in a significant increase in the number of lactobacilli (P < 0.01–0.0001) and bifidobacteria (P < 0.05–0.0001). Furthermore, a significant influence on the population size of lactobacilli and bifidobacteria was observed after administration of extracts from both cultivars to rats daily for 6 days in comparison with the control group. In rats gavaged orally with 4 ml kg⁻¹ day⁻¹ of BBE for 6 days, the population size of lactobacilli (P < 0.05) and bifidobacteria (P < 0.05–0.01) was increased significantly. We hypothesize that BBE could modify the bacterial profile by increasing the numbers of beneficial bacteria and thereby improving gut health.     

国内双歧杆菌制剂预防小儿继发性腹泻临床疗效的Meta分析

目的系统评价国内双歧杆菌制剂临床预防小儿继发性腹泻的效果。方法按照系统评价的要求检索CBMd isc、VIP、CNK I以及万方数据库等,获得18篇符合纳入标准的文献,共计患儿4050例,对其进行M eta分析,并评价M eta分析结果的稳定性和发表偏倚。结果异质性检验χ^2=34.60,P=0.007〈0.05,采用随机效应模型进行M eta分析,合并RR=0.41,95%C I为0.35～0.49,总体效应检验,Z=10.39,P〈0.00001,差异具有非常显著性,固定效应模型RR值和95%C I与随机效应模型完全一致,剔除小样本报道后的合并RR=0.42,95%C I为0.35～0.50,与剔除前的结果基本一致,且本研究的发表偏倚得到了很好地控制。结论从现有的临床证据来看,双歧杆菌制剂能降低小儿继发性腹泻的发生率,对预防小儿继发性腹泻起到了满意的效果。     

Diet and bacterial colonization: role of probiotics and prebiotics

The intestinal mucosa functions as a defensive barrier that limits dietary antigen transport and microbial pathogens from colonizing enterocytes. The potential role of lactic acid bacteria, specifically Bifidobacteria, in probiotic and prebiotic functional food supplements is reviewed in the context of bacterial colonization, adherence, and disease prevention. This article reviews the mechanisms of action and optimization of methods that will lead to a new generation of biotic products with enhanced biologic properties and well-being foods.     

Synthesis of prebiotic galactooligosaccharides from lactose using bifidobacterial β-galactosidase (BbgIV) immobilised on DEAE-Cellulose,Q-Sepharose and amino-ethyl agarose

The bifidobacterial β-galactosidase BbgIV was immobilised on DEAE-Cellulose and Q-Sepharose via ionic binding and on amino-ethyl- and glyoxal-agarose via covalent attachment, and was then used to catalyse the synthesis of galactooligosaccharides (GOS). The immobilisation yield exceeded 90% using ionic binding, while it was low using amino-ethyl agarose (25–28%) and very low using glyoxal agarose (<3%). This was due to the mild conditions and absence of chemical reagents in ionic binding, compared to covalent attachment. The maximum GOS yield obtained using DEAE-Cellulose and Q-Sepharose was similar to that obtained using free BbgIV (49–53%), indicating the absence of diffusion limitation and mass transfer issues. For amino-ethyl agarose, however, the GOS yield obtained was lower (42–44%) compared to that obtained using free BbgIV. All the supports tried significantly (P < 0.05) increased the BbgIV operational stability and the GOS synthesis productivity up to 55 °C. Besides, six successive GOS synthesis batches were performed using BbgIV immobilised on Q-Sepharose; all resulted in similar GOS yields, indicating the possibility of developing a robust synthesis process. Overall, the GOS synthesis operation performance using BbgIV was improved by immobilising the enzyme onto solid supports, in particular on Q-Sepharose.