传统发酵牦牛酸乳中益生性乳酸菌的体外筛选

为获得具有潜在益生特性的乳酸菌,实验以抗人工胃液、胆盐中生长效率和细胞表面疏水性为筛选指标,对羊八井地区传统发酵牦牛酸乳中分离出的38株乳酸菌进行体外筛选。最终通过测定结果综合比较得出菌株编号为YBJ-3、YBJ-11、YBJ-15、YBJ-17、YBJ-30和YBJ-33乳酸菌的益生特性较好,其中4株乳酸菌抗人工胃液能力大于90%,在胆盐中良好生长。通过16S r DNA序列分析鉴定,菌株编号YBJ-3为屎肠球菌(Enterococcus faecium)、YBJ-11为发酵乳杆菌(Lactobacillus fermentum)、YBJ-15为耐久肠球菌(Enterococcus durans)、YBJ-17为植物乳杆菌(Lactobacillus plantarum)、YBJ-30为植物乳杆菌(Lactobacillus plantarum)、YBJ-33为干酪乳杆菌(Lactobacillus casei)。     

具有抑制肠道致病菌和黏附Caco-2细胞作用的益生性乳酸菌的筛选及鉴定

为了筛选具有肠道益生特性的乳酸菌,进一步开发益生菌资源,本文研究采用牛津杯、人工模拟胃肠液及体外黏附Caco-2细胞等方法,以鼠李糖乳杆菌GG(Lactobacillus rhamnosus GG,LGG)为对照菌株,对实验室保藏15株乳酸菌的益生特性进行筛选与评估。实验结果表明:15株乳酸菌对两株沙门氏菌都具有一定抑制效果,抑菌圈直径为10.95~22.06 mm;乳酸菌C174、D24、D599、C37、D512具有较好的耐酸耐胆盐能力,在人工胃液3 h内存活率达到60%以上,人工肠液4 h内存活率达到80%以上;在黏附试验中,C174对Caco-2细胞具有较强黏附能力,黏附数量为740 CFU/100细胞,略高于对照菌株鼠李糖乳杆菌(543 CFU/100细胞);通过对具有高黏附性的菌株C174进行生理生化和16S rRNA分子测序鉴定,结果表明菌株C174为植物乳杆菌(Lactobacillus plantarum),命名为Lactobacillus plantarum ZJ-174。Lactobacillus plantarum ZJ-174的抑菌能力强、能够耐酸耐胆盐,并具有很强的黏附能力,是一株潜在的益生菌,具有治疗或预防人和动物肠道疾病等应用价值。     

产ACE抑制肽乳酸菌的筛选、益生特性评定及应用

目的:筛选出富产血管紧张素转化酶（Angiotensin converting enzyme,ACE）抑制肽的乳酸菌并评定其益生特性。方法:依据蛋白水解度及ACE抑制率对乳酸菌进行初筛,然后依据模拟胃肠消化后的ACE抑制率最终筛出2株乳酸菌ZJUIDS09和ZJUIDS11,进一步评价其耐酸、耐胆盐、抗生素耐药性和抑菌活性等益生特性,最后评定两株菌对荷斯坦脱脂乳、荷斯坦乳清、水牛脱脂乳和水牛乳清发酵后产物ACE抑制率。结果:筛选出菌株ZJUIDS09和ZJUIDS11,其发酵乳的蛋白水解度分别为5.79%±0.14%和5.75%±0.10%,ACE抑制率分别为87.39%±2.44%和90.41%±0.99%,IC₅₀值分别为0.31和0.25 mg/mL,经人工胃肠液消化后ACE抑制率分别为70.13%±0.15%和76.39%±2.91%。菌株ZJUIDS09和ZJUIDS11都具有良好的耐酸耐胆盐、抗菌和抗生素敏感性,经16S rDNA鉴定分别为罗伊氏乳杆菌（Lactobacillus reuteri）和瑞士乳杆菌（Lactobacillus helveticus）。通过对比同一蛋白浓度下不同底物（荷斯坦脱脂乳、荷斯坦乳清、水牛脱脂乳和水牛乳清）经菌株发酵后的ACE抑制率,确定菌株ZJUIDS09和ZJUIDS11的最佳发酵底物为荷斯坦脱脂乳。结论:本研究筛选的罗伊氏乳杆菌ZJUIDS09和瑞士乳杆菌ZJUIDS11有较强的产ACE抑制肽能力,具有开发降血压功能发酵乳制品的潜力。     

低盐泡菜中耐酸性乳酸菌的筛选'鉴定及特性研究

目的:筛选出具有潜在益生特性的乳酸菌菌株。方法:从含盐量≤6%的12份低盐泡菜中筛选出5株耐酸性乳酸菌,进行16S rDNA分子鉴定,并对其益生特性进行研究。结果:5株耐酸性乳酸菌分别为肠膜明串珠菌(Leuconostoc mesenteroides)J2、副干酪乳杆菌(Lactobacillus paracasei)N6、类植物乳杆菌(Lactobacillu paraplantarum)F8、食窦魏斯氏菌(Weissella cibaria)M1和食窦魏斯氏菌(Weissella cibaria)M12。其中,L.paracasei N6、W.cibaria M1和W.cibaria M12在pH 4.0培养基中相对生长率分别为84.23%,78.32%,76.29%,具有较强的耐酸能力;经pH 3.0胃液和pH 8.0肠液消化后,其存活率分别为79.26%,50.65%,53.37%,具有较强的耐受胃肠液能力;在0.3%胆盐中培养8 h后,其存活率均在30%以上,具有较强的耐胆盐能力;疏水率及自凝集率均在60%以上,具有较强的疏水及自凝集能力。结论:试验筛选得到3株具有益生特性的耐酸性乳酸菌菌株L.paracasei N6、W.cibaria M1和W.cibaria M12,可用于复合益生菌菌剂的研究。     

奶豆腐来源植物乳杆菌的益生特性评价

以奶豆腐来源的3株植物乳杆菌(Lactobacillus plantarum)为研究对象,分析了菌株的耐酸耐胆盐能力、表面疏水性和体外抗氧化能力,旨在评价菌株的益生特性。结果表明:植物乳杆菌对强酸和高胆盐具有较好的耐受能力,能保持较高的活性;供试菌株均对二甲苯的疏水性作用较强,而对三氯甲烷的疏水作用较弱;3株菌株均具有较好抗氧化活性。     

青藏高原牦牛酸奶中具有抗氧化活性乳酸菌的体内外益生特性

目的:筛选出性状优良的具有抗氧化性的益生乳酸菌并研究其对D-半乳糖致衰老模型大鼠的抗氧化作用。方法:以从青藏高原牦牛酸奶中初步筛选的3株具高抗氧化活性乳酸菌为研究对象,通过耐受模拟胃肠道、耐胆盐和疏水能力实验评价3株乳酸菌的体外益生特性,并将体外益生特性优良的菌株饲喂D-半乳糖致衰老模型大鼠。通过检测各处理组大鼠的脏器指数,肝脏、脑组织和血清中的谷胱甘肽过氧化物酶(glutathion peroxidase,GSH-Px)、总超氧化物歧化酶(total superoxide dismutase,T-SoD)活力、总抗氧化能力(total antioxidant capacity,T-AoC)以及丙二醛(malondialdehyde,MDA)含量来评价乳酸菌的体内抗氧化益生特性。结果:植物乳杆菌(Lactobacillus plantarum)XM5具有较强的耐模拟胃肠液和耐胆盐能力,同时具有较强的疏水能力。植物乳杆菌XM5的摄入能有效缓解D-半乳糖对大鼠脑组织的氧化损伤;使衰老模型大鼠肝脏中的GSH-Px活力,血清中的GSHPx、T-SoD活力和T-AoC显著提高(P0.05);同时使肝脏、脑组织和血清中的MDA含量显著降低(P0.05)。结论:植物乳杆菌XM5是一株性能优良的抗氧化益生乳酸菌,具有潜在的应用价值。     

酸笋中具有抗炎活性乳酸菌的筛选及鉴定

从柳州采集的3 份酸笋发酵液样品中分离筛选得到46 株疑似乳酸菌菌株,通过耐酸、耐胆盐、模拟胃肠道实验以及体外黏附HT-29细胞和NO实验进行益生特性和抗炎活性研究,筛选得到1 株具有优良抗炎活性菌株SS-31,经16S rRNA基因序列测序鉴定为发酵乳杆菌（Lactobacillus fermentum）。结果表明：菌株SS-31具有较强耐酸能力,0.1%牛胆盐处理3 h后活菌数为107 CFU/mL,存活率高达90.02%;模拟人工胃液消化2 h后存活率为80.28%,模拟人工肠液处理2 h后存活率为3.63%;SS-31在体外对HT-29细胞有较高黏附性,黏附率为4.47%,略低于对照菌鼠李糖乳杆菌（Lactobacillus rhamnosus）LGG（4.95%）;在体外脂多糖刺激RAW264.7细胞炎症中,与模型组相比,SS-31组显著下调炎性物质NO分泌量（P＜0.05）;此外,SS-31能显著下调炎症因子白细胞介素（interleukin,IL）1β、IL-6的含量（P＜0.05）。从酸笋发酵液中筛选得到1 株具有优良益生特性的发酵乳杆菌SS-31,初步证明了乳酸菌SS-31在治疗炎症中具有潜在应用和开发价值。     

发酵酸菜来源乳酸菌的益生特性及其在发酵乳中的应用

通过pH值、胆盐耐受性实验从发酵酸菜中筛选性能优良的益生乳酸菌株,经16S rRNA序列分析鉴定得4 株植物乳杆菌A44、B51、B54、C53和2 株戊糖乳杆菌A16、B72。经疏水、黏附、自凝聚和溶血能力实验评价6 株乳酸菌的益生特性,其中植物乳杆菌A44对氯仿和二甲苯的疏水性均大于80%,对Caco-2细胞的黏附率为13.57%,放置5 h的自凝聚率超过60%,与其他菌株相比具有更好的益生特性且无溶血活性。因此选用植物乳杆菌A44进一步研究其在发酵乳中的功能特性,结果表明：植物乳杆菌A44作为辅助发酵剂添加后对4 ℃贮藏7 d期间发酵乳pH值、滴定酸度和持水性均无显著影响（P＞0.05）,但是可以显著提高发酵乳的活菌数和黏度（P＜0.05）,活菌数达到8.45（lg（CFU/mL））。本研究筛选得到的植物乳杆菌A44是一株性能优良的益生乳酸菌,具有作为发酵乳益生菌辅助发酵剂的潜在应用前景。     

黔东南地区传统发酵白酸汤中乳酸菌的益生特性及应用

本研究以发酵酸汤为试验原料,通过pH值、胆盐耐受性实验筛选性能优良的乳酸菌,经16S r RNA序列分析鉴定得菌株1-3、1-6、ST-2、ST-11,4 株为副干酪乳杆菌,ST-10和ST-12为植物乳杆菌。通过评价菌株的疏水性、黏附性、自凝聚能力,筛选出了6 株具有益生特性的乳酸菌,其中副干酪乳杆菌1-6和植物乳杆菌ST-10对二甲苯、氯仿的疏水性均大于70%,放置24 h的自凝聚率较其他菌株都较优;不同菌株对抗生素表现出的敏感性、耐药性不尽相同。结果表明：副干酪乳杆菌1-6作为发酵剂添加后对酸汤pH值、总酸度均无显著影响(P＞0.05),但是活菌数与传统老酸汤发酵效果接近。本研究筛选得到的副干酪乳杆菌1-6 是一株性能优良的益生乳酸菌,为后续酸汤发酵益生菌的开发奠定基础。     

具有ACE抑制活性乳酸菌菌株的筛选与鉴定

以ACE抑制活性和蛋白水解活性为检测指标,选择138株乳酸菌为出发菌株,筛选出具有强ACE抑制活性的乳酸菌菌株.结果表明,筛选出具有强ACE抑制活性的4株乳酸菌,其中3株菌为瑞士乳杆菌,1株菌为干酪乳杆菌.瑞士乳杆菌KLDS1.0485和干酪乳杆菌KLDS1.0486比例为1:1,制成的发酵乳ACE抑制活性可达到61.55%.因此,组合瑞士乳杆菌KLDS1.0485和干酪乳杆菌KLDS1.0486可作为制备乳源ACE抑制肽的优良菌株.     

Antagonistic activities of lactobacilli against Helicobacter pylori growth and infection in human gastric epithelial cells

Lactobacilli have positive effects on bowel microflora and health in humans and animals. In this study, the antagonistic activities of Lactobacillus gasseri Chen, and L. plantarum 18 were assessed by agar plate diffusion assay and tests that determined the growth and urease activity of Helicobacter pylori cocultured with lactobacilli and the adherence of H. pylori to human gastric epithelial cells in the presence of lactobacilli. The results showed that the 2 Lactobacillus strains had significant anti-H.pylori activity, and this activity may be contributed by the cell-free supernatants (CFS) of lactobacilli and live Lactobacillus strains in vitro. The antagonistic activity of the CFS against H. pylori depended on the pH and the presence of metabolites, such as organic acids and proteases. Our results also indicated that 2 Lactobacillus strains could inhibit H. pylori adherence human gastric epithelial cells. PRACTICAL APPLICATION: Helicobacter pylori causes chronic gastritis, peptic ulcer disease, and gastric cancer, and it infects about 50% of the world's population. Lactobacilli have been reported to have an inhibitory effect on H. pylori and can be used as probiotic to manufacture dairy products preventing H. pylori infection.     

In vitro screening of lactobacilli with antagonistic activity against Helicobacter pylori from traditionally fermented foods

Helicobacter pylori may cause stomach diseases such as chronic gastritis, peptic ulcer, and gastric cancer, and several studies reported that lactobacilli have inhibitory effects on H. pylori. In this study, 38 Lactobacillus strains were screened for anti-H. pylori activity using in vitro methods, including survivability under the simulated gastric conditions, agar plate diffusion, urease activity, coaggregation, autoaggregation, and hydrocarbon analysis. The results indicate that 2 Lactobacillus strains showed potential anti-H. pylori activity in vitro. Lactobacillus plantarum 18 had the largest zone of inhibition and markedly reduced the urease activity of H. pylori. Lactobacillus gasseri Chen had higher coaggregation rate (58.15%) and hydrophobicity (59.27%) compared with the other strains. Further research is needed to verify the activities of these strains against H. pylori.     

四川牦牛奶和曲拉中九株乳酸菌的分子鉴定

为准确鉴定分离自我国四川鲜牦牛奶和曲拉中9株乳酸菌到种水平,作者运用16S rDNA序列分析、recA基因特异扩增和hsp60-RFLP等多种分子技术对分离自我国四川地区鲜牦牛奶和曲拉中的9株乳酸菌进行分类鉴定。结果证实,16S rDNA序列分析法可将9株乳酸菌初步归类为植物乳杆菌群(4株),肠膜明串珠菌(4株),瑞士乳杆菌(1株)。由于16S rDNA序列分析法不能区分植物乳杆菌和戊糖乳杆菌,为了进一步鉴定植物乳杆菌群中的4株菌,继续采用recA基因特异扩增和hsp60-RFLP技术对其细分,结果表明recA基因特异扩增和hsp60-RFLP的方法均能很好地把植物乳杆菌群中的4株菌鉴定到种水平,且均为植物乳杆菌。     

驼乳制品中抑制α-淀粉酶和α-葡萄糖苷酶活性乳酸菌的筛选及益生特性研究

目的:本研究以新疆阿勒泰地区的驼乳制品为研究对象,筛选对α-淀粉酶和α-葡萄糖苷酶有抑制活性的优良乳酸菌。方法:采用稀释涂布法分离纯化菌株,DNS和pNPG法筛选对α-淀粉酶和α-葡萄糖苷酶有抑制活性的菌株,通过耐酸性、耐胆盐、模拟胃肠道环境耐受性、抑菌性、抗氧化活性实验评价菌株的益生特性。结果:从驼乳制品中共计获得34株菌株,其中6株对α-淀粉酶和α-葡萄糖苷酶有抑制活性,经过形态学和16S rRNA分子鉴定,确定有4株为植物乳杆菌Lactiplantibacillus plantarum,2株为副干酪乳杆菌Lactiplantibacillus paracasei。6株乳酸菌对α-淀粉酶的抑制活性都达到50%以上,其中X34对α-淀粉酶的抑制率最高达到88.59%。本实验中筛选的乳酸菌对α-葡萄糖苷酶的抑制率在11%~16%之间,X31抑制率最高为15.43%。6株乳酸菌在不同pH（1.0、2.0、3.0）和不同浓度胆盐（1、2、3 g/L）的培养基中均可存活。6株乳酸菌在模拟胃液和肠液中的存活率分别达到83%和90%以上。对羟自由基和超氧阴离子自由基的清除率超过90%以上,其中X29对羟自由基的清除率最高为92.43%,对超氧阴离子自由基清除率最强的是X33清除率达到94.04%。6株乳酸菌对大肠杆菌、沙门氏菌和金黄色葡萄球菌有一定的抑制作用,其中X31对大肠杆菌的最大抑菌圈直径为19.63 mm,X23对沙门氏菌抑菌圈最大达到19.85 mm,菌株X33对金黄色葡萄球菌的抑菌圈直径最大为19.17 mm。结论:从驼乳制品中筛选到6株具有潜在降糖活性的乳酸菌,对强酸、胆盐和胃肠液有一定的耐受性,抗氧化能力较强,具有抑制致病菌的效果,为后期研发功能性降糖饮品提供益生菌株。     

西部传统发酵乳品中乳酸菌筛分及其亚硝酸盐降解能力

为探究西部牧区传统发酵乳品中乳酸菌多样性及其优势菌种的亚硝酸盐降解能力,为工业化利用提供参考,应用16S rDNA技术鉴定分离菌株,并对分离菌株亚硝酸盐降解能力采用比色法进行分析,比较不同地区、不同发酵乳品中不同种类乳酸菌亚硝酸盐降解能力的差异。结果表明：1）104?份样品中共分离得到275?株乳酸菌,鉴定出6?个属23?个种,其中瑞士乳杆菌（Lactobacillus helveticus）为青海、甘肃、新疆、内蒙古、西藏传统发酵乳品中共有菌株,L. helveticus和植物乳杆菌（L. plantarum）为酸牦牛奶、酸马奶、酸驼奶、奶渣发酵乳品中共有菌株。2）275?株乳酸菌亚硝酸盐降解率在4.8%～99.9%之间波动,其中50%的菌株表现出较好的亚硝酸盐降解能力,平均在91.3%以上。3）降解能力因菌株来源和乳酸菌种类不同存在差异性,来源于西藏的菌株显著高于青海、甘肃、新疆的菌株（P＜0.05）;来源于奶渣中的菌株显著高于酸牦牛奶和酸马奶中的菌株（P＜0.05）;在分离出的8?种优势菌株中L. plantarum、副干酪乳杆菌（L. paracasei）、短乳杆菌（L. breris）显示了稳定高效的亚硝酸盐降解能力,其中L. plantarum降解能力最强,且部分菌种间降解能力存在显著性差异（P＜0.05）。     

Metabolic activities of Lactobacillus spp. strains isolated from kefir

A total of 21 strains of Lactobacillus species were isolated from Turkish kefir samples, in order to select the most suitable strains according to their metabolic activities including probiotic properties. As a result of the identification tests, 21 Lactobacillus isolates were identified as L. acidophilus (4%), L. helveticus (9%), L. brevis (9%), L. bulgaricus (14%), L. plantarum (14%), L. casei (19%) and L. lactis (28%). The amount of produced lactic acid, hydrogen peroxide, proteolytic activity, and acetaldehyde productions of Lactobacillus spp. were determined. Different amounts of lactic acid were produced by strains studies; however, lactic acid levels were 1.7-11.4 mg/mL. All strains produced hydrogen peroxide. L. bulgaricus Z14L strain showed no proteolytic activity, L. casei Z6L strain produced the maximum amount (0.16 mg/mL) of proteolytic activity. Acetaldehyde concentration produced in Lactobacillus strains ranged between 0.88-3.52 microg/mL.     

Screening of potential lactobacilli antigenotoxicity by microbial and mammalian cell-based tests

Antigenotoxicity is considered an important property for probiotic lactobacilli. The ability of non probiotic lactobacilli from dairy products and starters to inhibit two reference genotoxins: 4-nitroquinoline-1-oxide and N-methyl-N'-nitro-N-nitrosoguanidine was evaluated. The study was carried out using short-term assays with different targets, such as procaryotic cells (SOS-Chromotest for genotoxicity in Escherichia coli and Ames test for mutagenicity in Salmonella typhimurium) and eucaryotic cells (Comet assay for genotoxicity in Caco-2 enterocytes). A high proportion of strains inhibiting 4-nitroquinoline-1-oxide activity was found in Lactobacillus casei, Lactobacillus acidophilus, Lactobacillus rhamnosus, Lactobacillus delbrueckii subsp. bulgaricus and Lactobacillus plantarum. Inhibition of N-methyl-N'-nitro-N-nitrosoguanidine activity occurred in only one L. acidophilus strain. All the strains with antigenotoxic properties also demonstrated antimutagenic activity and produced modifications in genotoxin spectroscopic profiles. Strain viability during and after genotoxin exposure was confirmed. Concordance of the results obtained with microbial and mammalian cell-based tests is underlined.     

浙东腌冬瓜优势乳酸菌的分离及产酶特性分析

通过微生物分离和鉴定从浙东传统腌冬瓜中得到4株优势菌,分别为植物乳杆菌(Lz151)、发酵乳杆菌(Lz152)、棒状乳杆菌(Lz153)和戊糖乳杆菌(Lz154),通过酶学分析方法对4株乳酸菌的产生乳酸脱氢酶、亚硝酸盐还原酶、酯酶和转氨酶的特性进行研究。实验表明,4株乳酸菌都有乳酸脱氢酶、亚硝酸盐还原酶、酯酶和转氨酶活性,植物乳杆菌和发酵乳杆菌有较高的乳酸脱氢酶活力,分别达到122.34 U/m L和113.56 U/m L;发酵乳杆菌和戊糖乳杆菌有较高的亚硝酸盐还原酶活性,分别为17.62 U/m L和13.42 U/m L,而棒状乳杆菌具有最低的亚硝酸盐还原酶活力,为4.74 U/m L;植物乳杆菌和棒状乳杆菌比其他两种乳酸菌有较高的酯酶活性,达到11.53 U/m L和13.78 U/m L。此外,植物乳杆菌和戊糖乳杆菌有较高的转氨酶活性,分别为25.37 U/m L和23.19 U/m L。4株乳酸菌产酶的最适温度和p H存在菌种间差异,而且同一株菌产生各种酶的最适条件也不同,分离乳酸菌分别在30℃、35℃、40℃产各种酶的能力最高,而发酵乳杆菌、植物乳杆菌的最适产酶p H分别为6.0、7.0。