鲈鱼肠道来源降胆固醇乳酸菌分离筛选及其益生功能评价

该研究探讨了从健康鲈鱼肠道中筛选分离出高效降胆固醇的乳酸菌,通过菌株鉴定、耐酸、耐胆盐、疏水性、自凝聚力和代谢物抑菌性评价的测定,评价并考察其体外益生作用。采用胆盐水解酶测定和体外降胆固醇试验,筛选分离得到一株高效降胆固醇的菌株ZG2YLu05,其胆盐水解酶（BSH）粗酶活和胆固醇去除率分别为0.82 µmol/(h?mL)和50.09%;在pH 3.0的培养条件下培养8 h,菌株的耐酸存活率为83.33%;在胆盐浓度0.3%的培养条件下培养8 h,菌株的耐胆盐存活率高达89.31%;在二甲苯中菌株的疏水性为46.82%,静置24 h后菌株的自凝聚力为92.93%,说明菌株具有良好的黏附潜力;菌株代谢物对大肠杆菌、金黄色葡萄球菌和沙门氏菌都有明显的抑制作用;经形态学观察和16S rDNA鉴定为戊糖乳杆菌（Lactiplantibacillus pentosus）。该菌株能够作为潜在降胆固醇乳酸菌用于开发辅助降脂益生菌制剂的生产。     

高效降胆固醇降甘油三酯乳酸菌的分离鉴定和功能分析

筛选出高效降胆固醇降甘油三酯(Triglyceride,TG)菌株,为新型药物、保健食品的研制提供优良菌株。从6种西北特有样品中筛选分离出乳酸菌,采用磷硫铁比色法测定菌株降胆固醇能力,并测定菌株降甘油三酯能力,通过抑菌实验、耐酸、耐胆盐及小鼠体内毒性试验研究菌株各项性能,利用生理生化及16S rDNA法对菌株进行鉴定。结果表明,本试验筛选出3株高效降胆固醇降甘油三酯乳酸菌,其中菌株ZL010降胆固醇、降甘油三酯效果最强,蛋黄中胆固醇的降解率为73.65%,高纯度胆固醇降解率为40.06%,甘油三酯降解率为5.10%。3株菌都具有很好的抑菌、耐酸、耐胆盐能力,菌株经生理生化及16S rDNA鉴定ZL005为耐久肠球菌(Enterococcus durans),ZL010为植物乳杆菌(Lactobacillus plantarum),ZL016为戊糖乳杆菌(Lactobacillus pentosus)。小鼠毒性试验表明,菌株无毒副作用,小鼠各脏器一切正常,菌株可用于降脂降胆固醇保健药品及功能食品的制备。     

传统发酵肉源乳酸菌介导NPC1L1、ABCG5/G8基因表达对胆固醇代谢的影响

过高的胆固醇摄入可能会导致机体心脑血管出现健康问题。通过乳酸菌可以调控小肠中胆固醇代谢相关基因的表达,调节机体内胆固醇的吸收代谢,从而影响体内胆固醇含量。对15株传统发酵肉制品中分离筛选的乳酸菌进行体外降胆固醇能力和耐酸耐胆盐能力筛选,将筛选到的乳酸菌用于动物实验。结果表明,15株乳酸菌中有4株乳酸菌(CM6、CM9、CM28、CM42)具有良好的体外降胆固醇能力,平均降解率为52.92%。对它们进行耐酸和耐胆盐试验,在pH 2和0.3%胆盐添加量的条件下菌株CM6活菌数达到106 CFU/mL,选择CM6进行后续动物实验。乳酸菌灌胃小鼠30 d后,乳酸菌组小鼠血清中总胆固醇含量和甘油三酯含量乳显著低于对照组(P＜0.05);乳酸菌组小鼠小肠中NPC1L1基因相对表达量显著低于对照组(P＜0.05),ABCG5/G8基因表达量显著高于对照组(P＜0.05)结论:乳酸菌CM6具有调控胆固醇代谢相关基因表达的能力,从而降低体内胆固醇含量。     

两株乳酸菌对高脂模型大鼠的益生作用

为探究两株筛选自青藏高原传统发酵牦牛酸奶乳酸菌高脂模型大鼠体内的益生作用。通过前期体外实验发现,菌株BX-1是一株产胆盐水解酶的瑞士乳杆菌,而BX56是一株不产胆盐水解酶的罗伊氏乳杆菌。大鼠体内灌胃实验结果显示,灌胃瑞士乳杆菌BX-1能够显著降低大鼠血清和肝脏胆固醇及甘油三酯水平(P0.05),同时能够减少脂类物质在大鼠肝脏组织内的沉积,促进体内脂质的排泄,而灌胃罗伊氏乳杆菌BX56在大鼠体内降血脂的效果并不明显。结果表明瑞士乳杆菌BX-1具有良好降胆固醇效果,具有潜在的治疗高脂血症的作用。     

一株高效降解胆固醇乳酸菌的筛选鉴定及其益生潜能初探

从新鲜牛粪中分离出的5株乳酸菌中筛选得到一株具有高效降胆固醇能力的乳酸菌,其体外胆固醇脱出率达到50.83%。经API50CHL系统及16S rRNA序列比对鉴定为发酵乳杆菌Lactobacillus fermentum,命名为发酵乳杆菌DF-4。模拟胃液中的低pH和小肠中的胆汁盐浓度进行了耐受性试验,结果表明该菌株具有较强的耐酸和耐胆盐的性能,对致病大肠杆菌和金黄色葡萄球菌均有显著抑制作用,是一株具有开发前景的高效降胆固醇的益生菌。     

贵州泡菜中乳酸菌的分离鉴定及其在泡菜发酵中的应用

以贵州遵义市采集的不同家庭自制的11份发酵泡菜制品为材料,从中筛选产酸量较高的乳酸菌,通过形态观察、生理生化试验及分子生物学技术对其进行鉴定,并对其耐酸、耐胆盐、耐盐及抑菌性能进行测定,筛选性能优良的乳酸菌,最后将其应用到发酵泡菜中。结果表明,筛选得到11株产酸量较高的乳酸菌,产酸量均＞1.89 g/L,经鉴定5株为植物乳杆菌（Lactobacillus plantarum）,6株为副植物乳杆菌（Lactobacillus paraplantarum）,其中菌株A50f7和A50b9的耐酸、耐胆盐、耐盐及抑菌性能优良。人工接种这两株乳酸菌发酵泡菜,能显著缩短泡菜发酵周期,改善泡菜的品质。     

酸浆中高产酸乳酸菌的筛选及其发酵黄浆水风味特征研究

针对贵州酸浆的优势产酸微生物菌株特性及其风味成分不明晰的现状。本研究通过比较产酸乳酸菌的耐酸、耐胆盐、氨基酸脱羧酶活性、抑菌性、生长曲线及产酸速率等特性,旨在筛选出高产酸乳酸菌,并借助GC-MS分析菌株对酸浆中挥发性风味成分的影响。结果表明,从分离纯化出的70株乳酸菌中,获得18株高产酸的乳酸菌。其中植物乳杆菌L4和发酵乳杆菌L6在发酵36 h时pH值降至3.67和3.71,具备耐酸、耐胆盐及较好的抑菌性等特点。两株菌协同接种发酵,酸浆的主要风味物质为酸类和酮类,赋予了酸浆独特的风味,有望开发作为工业化生产酸浆的发酵剂。本研究在指导企业标准化、规模化生产酸浆方面具有比较重要的理论和实践指导意义。     

一株降胆固醇乳酸菌的筛选、鉴定及在发酵泡菜中的应用

对降胆固醇乳酸菌进行了筛选和鉴定。采用MRS培养平板从泡菜中筛选出99株接触酶试验为阴性、革兰氏染色为阳性、有明显透明钙圈的菌株,并分别测定它们的降胆固醇作用。胆固醇降解率大于30%的有8株,其中I4的降解率为37.3%±1.50%(n=3)。通过生理生化试验和16SrRNA序列分析法,鉴定菌株I4为植物乳杆菌(Lactobacillus plantarum)。对植物乳杆菌I4进行了耐酸、耐胆盐试验的研究,实验表明植物乳杆菌I4具有很好的耐酸能力和一定的耐胆盐能力。对降胆固醇植物乳杆菌I4菌制剂在发酵泡菜中的应用进行研究。实验表明:与未添加I4菌种的发酵泡菜对比,泡菜成熟时间缩短,亚硝酸盐含量降低,总酸与总氨基态氮没有差异,感官检验没有差异,并进行了微生物指标测定,符合国家GB 2714-2003《酱腌菜卫生标准》。     

植物源益生乳酸菌的筛选及其特性

为筛选具有益生特性的植物源乳酸菌,以传统发酵蔬菜中分离的1 000 株乳酸菌为出发菌株,进行了耐酸性、耐胆盐能力、抑菌性、体外抗氧化能力、药敏性、溶血性和氨基酸脱羧酶活性等特性研究,并对筛选菌株进行了16S rDNA 鉴定。经pH 3.0 MRS培养得乳酸菌82 株,再经pH 2.5 MRS培养得乳酸菌49 株;49 株菌经0.3%胆盐测试,均具有耐胆盐能力;根据镜检形态结合发酵植物源的不同从中挑选19 株乳酸菌进行药敏性、溶血性、抑菌性、氨基酸脱羧酶活性和1,1-二苯基-2-三硝基苯肼自由基清除实验。结果表明,19 株菌对所选20 种抗生素多数表现敏感,其中4 株菌对20 种抗生素都较敏感;19 株菌对供试致病菌都有不同程度抑制能力且都无溶血性;经氨基酸脱羧酶活性试剂盒结合聚合酶链式反应扩增检测表明,19 株菌无产生物胺的潜在威胁;有5 株菌体外抗氧化能力高于40%。可见19 株菌均具有益生菌的基本特性。经16S rDNA鉴定,7 株为发酵乳杆菌、6 株为植物乳杆菌,嫩江杆菌、戊糖片球菌、利莫西杆菌、戊糖乳杆菌、屎肠球菌、短乳杆菌分别各1 株。     

产胆盐水解酶BSH乳酸菌的鉴定及发酵条件优化

目的:鉴定降胆固醇和产胆盐水解酶的乳酸菌菌株,并通过优化发酵条件提高胆盐水解酶酶活.方法:对初步筛选的乳酸菌菌株Lp-1进行体外降胆固醇试验,采用PCR方法鉴定菌株中的胆盐水解酶基因,用16SrRNA方法鉴定该菌株,并对该菌株发酵培养基和发酵条件进行优化.结果:乳酸菌菌株Lp-1具有体外降胆固醇功能,基因组中含有胆盐水解酶基因,其脱氧核糖核苷酸序列与已发表的胆盐水解酶基因同源性为98.9%;该菌株与已发表的植物乳杆菌16S rRNA同源性为99%;通过发酵条件优化,以葡萄糖为碳源,蛋白胨、酵母粉为氮源,碳氮比1∶1,初始pH 6.5,接种量7%,在37 ℃下培养14 h,胆盐水解酶酶活最高达到11.2 U/mL.结论:鉴定到1株植物乳杆菌Lp-1(Lactobacillius plantarum Lp-1),该菌含有胆盐水解酶基因,并产胆盐水解酶;发酵条件优化后该菌产胆盐水解酶活力比优化前提高6倍.     

发酵风干肠中乳酸菌的发酵性能

对从自然发酵风干肠中分离的6 株乳酸菌的发酵性能进行评价,主要包括测定菌株的生长曲线、产酸能力、对NaCl及NaNO2的耐受能力,同时通过吲哚实验和抗生素敏感性测定对菌株的安全性进行初步评价。结果表明：6 株乳酸菌生长趋势接近,均在8 h左右进入生长稳定期,pH值在0～8 h下降最快,清酒乳杆菌和发酵乳杆菌的产酸能力更强;所有菌株均可在6 g/100 mL NaCl和0.015 g/100 mL NaNO2条件下生长,植物乳杆菌和弯曲乳杆菌的NaCl耐受能力最优,清酒乳杆菌和发酵乳杆菌则对NaNO2具有最强的耐受能力;吲哚实验中6 株乳酸菌的反应结果均为阴性,对实验所选抗生素无耐药性,说明6 株乳酸菌具有较好的发酵性能和安全性,可作为功能性发酵剂用于发酵肉制品的生产。     

Identification of lactic acid bacteria in traditional fermented yak milk and evaluation of their application in fermented milk products

In this study, 53 strains of lactic acid bacteria (LAB) isolated from Xueo, a traditional fermented yak milk in the western Sichuan Plateau of China, were identified and their use in fermented milk was evaluated. All gram-positive and catalase-negative strains were divided into 6 groups at the level of 87% similarity using amplified ribosomal DNA restriction analysis. These groups were identified as 6 species using 16S rDNA sequence analysis and atpA gene analysis. The dominant LAB strains in Xueo were Enterococcus durans, Lactobacillus fermentum, and Lactobacillus paracasei, accounting for 45.3, 22.6, and 17.0% of isolates, respectively. Milk fermented with most of the representative strains was high in quality, exhibiting relatively high viscosity, moderate acidity, good sensory quality, and high counts of viable LAB. Fermented milk of E. durans SCA16 and L. fermentum SCA52 achieved the highest scores for overall sensory quality. Most strains displayed antimicrobial activity against at least 1 of 9 spoilage microorganisms. Lactic acid was the main factor inhibiting the growth of spoilage bacteria, and H(2)O(2) was also inhibitory to some extent. Excluding the influence of acid and H(2)O(2), strains SCA52 (L. fermentum) and SCA7 (Lactobacillus plantarum) were antagonistic against some of the indicators, suggesting that the 2 strains may produce a bacteriocin-like substance. Therefore, the development of superior strains isolated from Xueo to ferment milk with similar flavor and texture to Xueo is expected.     

Identification and Characterization of Lactic Acid Bacteria Involved in Natural and Lactic Acid Bacterial Fermentations of Pastes of Soybeans and Soybean-Maize Blends Using Culture-Dependent Techniques and Denaturing Gradient Gel Electrophoresis

Pastes of soybeans and soybean-maize blends were fermented with inoculum through back-slopping using lactic acid bacteria (LAB) fermented cereal gruel, thobwa and without inoculum (naturally). LAB involved in the fermentations were characterized using culture-dependent and culture-independent analyses. Decreases in pH from 6.4 to 3.9–4.2 and from 6.9 to 5.4–5.8 after 72 h were observed in LAB fermented pastes (LFP) and in naturally fermented pastes (NFP), respectively. LAB increased from 5.0 to 8.7–9.6 log₁₀ cfu/g in NFP and from 8.1 to 9.3 log₁₀ cfu/g in LFP. LAB in both fermentations were heterofermentative lactobacilli (82.4%) and homofermentative cocci (17.6%), of which 44.7% and 42.9% were exopolysaccharide producers, respectively. Principal component analysis based on carbohydrate fermentation, CO₂ production and arginine hydrolysis showed four clusters dominated by Lactobacillus fermentum, Weissella confusa, Lactobacillus brevis 1 and Pediococcus pentosaceus, respectively. Sequencing of 16S rDNA gene confirmed Lb. fermentum, W. confusa/W. cibaria, and P. pentosaceus as identities of species in three clusters. Denaturing gradient gel electrophoresis (DGGE) confirmed these species as the dominant microbiota. DGGE showed higher similarity in microbial profiles of LFP throughout fermentation and low similarity in NFP during early and late stages of fermentation.     

降胆固醇乳酸菌的筛选及其益生元干预生长作用分析

本研究从传统自然发酵的酵素饮品中分离筛选出一株高效降胆固醇菌株,该菌株具有较好的胆盐耐受性和耐酸能力。在pH3的酸性环境下,耐酸率为71.53%,该菌株能够长时间耐受胆盐环境,培养16h的胆盐耐受率为42.09%。以二甲苯为吸附剂,疏水率为35.91%,有较好的黏附特性;益生元不仅能够促进菌株生长,而且可显著提高降胆固醇能力。4种益生元中乳果糖促进生物量增加幅度最大,培养至16 h时生物量达到最高。乳果糖对菌株产酸性能影响最显著,pH值可降至3.56,胆固醇去除率达41.10%。该菌株对菊粉的利用率低,说明菌株对不同益生元具有选择性代谢。菌株经形态学观察和16S rDNA鉴定为副干酪乳杆菌,并命名为Lactobacillus paracasei S0940。本研究为进一步研究体内降脂能力以及开发功能性乳酸菌食品提供理论依据。     

Evaluation of Probiotic Potential of Lactic Acid Bacteria Isolated from Different Sources in Western India

Lactic acid bacteria isolated from unconventional sources are often attractive targets in the quest for obtaining better probiotics. In the present study, 16 members of the genus Lactobacillus, isolated from 3 different sources in western India, viz., plants, fermented foods and beverages, and human feces, were evaluated for their probiotic and bioactive properties. The isolates were closely related to Lactobacillus fermentum, Lactobacillus pentosus, and mainly Lactobacillus plantarum. The isolates were tolerant to bile salt, acidic pH and pancreatin, although pancreatin tolerance was generally low. Cellular extracts of several isolates displayed antioxidant activity, while cell-free supernatants displayed antibacterial activity against human pathogens. Antioxidant activity of Lactobacilli of human origin was higher than those from vegetables or fermented foods and beverages. L. plantarum AG40V prevented spoilage of fresh-cut fruits, vegetables and sprouted mung-beans. Lactobacilli from all sources displayed equal probiotic potential and those of human origin displayed superior antioxidant activity over others.     

自然发酵豆酱中嗜盐四联球菌的分离筛选及生长特性研究

以采集自不同地区的14份自然发酵豆酱为试材,对其中的嗜盐四联球菌（Tetragenococcus halophilus）进行分离鉴定及益生特性研究,同时进一步探讨优良菌株的最佳生长条件,并通过单因素试验及响应面试验对其增殖培养基进行优化。结果表明,分离鉴定得到10株嗜盐四联球菌。其中,嗜盐四联球菌YSJ-5具有良好的耐酸、耐胆盐特性及抑菌特性,其最适培养条件为接种量3%、NaCl含量5%、培养温度33 ℃、初始pH值8.0。在此最适培养条件下,最适增殖培养基成分为葡萄糖2.70%,蛋白胨2.36%,黄豆浆4.41%,嗜盐四联球菌YSJ-5的活菌数为2.20×109 CFU/mL。     

利用16S rDNA序列及tuf-RFLP鉴定蒙古国发酵乳中的乳酸菌

运用16S rDNA序列分析和tuf-RFLP技术对采于蒙古国扎布汗省的25份发酵乳样中分离出的110株乳酸菌进行鉴定。首先将分离的110株乳酸菌的16S rRNA基因进行扩增,测序并构建系统发育树,初步鉴定为41株嗜热链球菌,40株瑞士乳杆菌,11株德氏乳杆菌保加利亚亚种,2株发酵乳杆菌,1株乳明串珠菌,2株肠膜明串肠膜亚种,1株乳酸乳球乳酸亚种和12株属于干酪族的菌株。由于干酪乳杆菌族的16S rDNA序列差异很小,故采用tuf-RFLP技术对这12株进行了进一步的验证,通过分离菌株与模式菌株tuf-RFLP图谱的比较分析,结果表明这12株菌均为干酪乳杆菌。     

Functional characteristics of Lactobacillus spp. from traditional Maasai fermented milk products in Kenya

In this study functional characteristics of 23 representative Lactobacillus strains isolated from the Maasai traditional fermented milk 'Kule naoto' were determined. The Lb. acidophilus group strains showed resistance to gastric juice and bile. In addition, some Lb. acidophilus strains expressed bile salt hydrolase activity, and had ability to assimilate cholesterol in vitro. In-vitro adhesion to HT29 MTX cells of up to 70% was recorded. Lb. fermentum strains showed almost 100% survival under simulated stomach acidic conditions and physiological salt concentrations of bile salts, hydrophobicity values were over 80%. Most strains of the Lb. casei and Lb. acidophilus groups showed aggregation abilities of above 50%. Many strains expressed a protective effect against N-methyl-N'-nitro-N-nitrosoguanidine induced DNA damage according to the 'comet assay' and none was virulent. The antibiotic minimum inhibitory concentration of selected strains was established. According to these results, the Lactobacillus spp associated with 'Kule naoto', contain potentially probiotic (functional) strains.     

具有降胆固醇能力的人源乳酸菌筛选

分离筛选出长寿人群肠道中具有益生功能的乳酸菌,并研究其体外降解胆固醇能力。结果表明分离获得的80株乳酸菌中,9株菌在模拟胃液中培养3 h的存活率较高,分别为26.60%、24.30%、22.50%、16.72%、46.61%、16.10%、19.80%、19.60%、17.80%,在0.30%、0.50%及1.00%的胆盐培养基中存活率最高的菌株为o2,存活率分别为21.31%、13.35%及12.43%;9株菌对氨苄青霉素、青霉素G、氯霉素敏感,对四环素、利福平、环丙沙星敏感或中度敏感;9株菌对三株致病菌均有抑制作用,其中V9、o2分别对沙门氏菌、金黄色葡萄球菌抑制能力较强,抑菌圈直径分别为12.00 mm、11.40 mm,9株菌对大肠杆菌的抑制作用普遍较强,抑菌圈直径均大于7.00 mm;9株菌中f10、o2、T1及V9的胆固醇降解率较高,分别为45.85%、40.76%、41.70%、42.87%,经生理生化试验及16S rDNA测序鉴定分别为屎肠球菌、食窦魏斯氏菌、干酪乳杆菌及发酵乳杆菌,是良好的辅助降血脂候选菌株。     

泡菜源乳酸菌的分离筛选及其对小鼠氧化应激水平的改善作用

为筛选具有较好体外抗性以及体内抗氧化效果的乳酸菌,本研究从重庆农家自然发酵泡菜中分离得到12株菌株,经16S rDNA种属分析表明,其中植物乳杆菌（Lactobacillus plantarum） 4株,发酵乳杆菌（Lactobacillus fermentum） 7株,短乳杆菌（Lactobacillus brevis） 1株。采用pH 3.0人工胃液和0.3%胆盐对乳酸菌进行体外抗性筛选,发现12株乳酸杆菌具有较好的体外抗性,其中10株乳酸杆菌在pH 3.0人工胃液中处理3 h后的存活率超过80%;2株乳酸杆菌在0.3%胆盐中的存活率超过60%。选取体外抗性好且为食品可用菌种的Lactobacillus fermentum CQPC-11（L. fermentum CQPC-11）为实验菌株,评价其对活性炭冰水诱导氧化应激损伤小鼠的改善作用,结果表明H-LF CQPC11组小鼠血清中总超氧化物歧化酶（T-SOD）、谷胱甘肽过氧化物酶（GSH-Px）和过氧化氢酶（CAT）的酶活力分别为67.73 U/mL、2742.35酶活力单位、136.59 U/mL,显著高于模型组（p<0.05）,而丙二醛（MDA）的含量为1.99 nmol/L,显著低于模型组（p<0.05）。综上所述,L. fermentum CQPC-11不仅具备良好的耐胃酸和耐胆盐能力,还能降低氧化应激模型小鼠的氧化应激反应,可通过后续进一步的实验探讨该菌株抗氧化作用的具体机理,为新型微生态制剂以及功能性乳酸菌食品的开发提供理论依据和可用菌株。