Characterisation of Lactobacillus fermentum SM-7 isolated from koumiss, a potential probiotic bacterium with cholesterol-lowering effects

BACKGROUND: Lactic acid bacteria (LAB) have been demonstrated to have cholesterol‐reducing effects in many studies. RESULTS: Lactobacillus fermentum SM‐7 screened from ten LAB strains isolated from koumiss, a fermented milk drink, reduced cholesterol by 66.8%. It also showed acid and bile tolerance as well as antimicrobial activity against pathogenic Escherchia coli and Staphylococcus aureus. Lactobacillus fermentum SM‐7 cells assimilated 61.5% and co‐precipitated and absorbed 38.5% of the cholesterol in the media. Co‐precipitation of cholesterol with cholic acid increased rapidly at pH levels below 6. In vivo experiments using L. fermentum SM‐7 on artificially induced hyperlipidaemial ICR mice significantly decreased serum total cholesterol and total triglyceride levels, low‐density lipoprotein cholesterol concentrations and atherogenic index (P < 0.01), while serum high‐density lipoprotein cholesterol concentrations did not increase significantly (P > 0.05). The body weight and liver weight/body weight ratio of SM‐7 groups were lower than those of mice on a high‐cholesterol diet that were not given lactobacilli. There was no bacterial translocation in the liver, spleen or kidney of experimental mice. CONCLUSION: The results suggested that L. fermentum SM‐7 is a potential probiotic bacterium with cholesterol‐lowering effects. Copyright © 2010 Society of Chemical Industry     

发酵乳杆菌CQPC04减轻小鼠血栓形成和调节肠道菌群的效果

本研究通过给小鼠注射0.01 mL/(g mb·d)质量分数0.2%的角叉菜胶建立血栓形成模型,分析以0.2 mL/(g mb·d)不同浓度(1×10⁸ CFU/mL和1×10⁹ CFU/mL)发酵乳杆菌(Lactobacillus fermentum)CQPC04(以下简称LF-CQPC04)菌悬液干预10 d对小鼠凝血情况、氧化应激水平、炎症水平及肠道微生物组成的影响。分别采用生化试剂盒、苏木精-伊红染色切片观察、定量聚合酶链式反应分析小鼠血清和组织的相关指标,并通过高通量测序分析小鼠肠道微生物组成。结果表明,LF-CQPC04干预可以缩短血栓性小鼠的黑尾长度、凝血酶原时间、凝血酶时间,同时减少血液中纤维蛋白原质量浓度,延长血栓性小鼠的活化部分凝血活酶时间。LF-CQPC04干预还可降低血栓性小鼠血清中丙二醛、肿瘤坏死因子(tumor necrosis factor,TNF)-α、白细胞介素(interleukin,IL)-6、核因子(nuclear factor,NF)-κB和IL-1β的水平,并提高超氧化物歧化酶和过氧化氢酶(cata...     

酸菜中降胆固醇功能植物乳杆菌的体外筛选

以分离自东北家庭自制酸菜中的9株植物乳杆菌为研究对象,采用邻苯二甲醛法筛选具有降胆固醇功能的乳杆菌,并通过耐酸、耐胆盐及抗生素敏感性实验,分析菌株的益生特性。结果表明,多株植物乳杆菌具有良好的降胆固醇功能,其中菌株S56的脱除胆固醇的量最高,达到22.40μg/mL。实验菌株均能耐受pH 3.0的酸度和10 g/L的牛胆盐。其中菌株S2-6、S2-5、S4-1和S56在pH 2.0的环境中能保持生长1 h,具有较强的耐酸性。     

老年人肠道乳酸菌的分离与鉴定及其来源发酵乳杆菌的遗传进化分析

首先对湖北襄阳和恩施地区的健康老年人肠道乳酸菌进行分离与鉴定,然后从中选择发酵乳杆菌（Lactobacillus fermentum）进行多位点序列分型（multilocus sequence typing,MLST）分析。结果显示,基于可培养方法,湖北襄阳与恩施地区老年人肠道乳酸菌可以鉴定为以乳杆菌属（Lactobacillus）为主的5 个菌属,15 个种。总的来说,发酵乳杆菌和唾液乳杆菌（L. salivarius）占老年人肠道源乳酸菌分离株总量的55%左右,表明人体肠道可以作为发酵乳杆菌的重要分离来源。基于8 个持家基因的MLST分析表明,25 株来源于肠道的发酵乳杆菌可以划分为25 个序列型,具有极高的遗传多样性;基于选择压力分析与phi-test,选用的8 个持家基因均受到纯化选择作用,且其中仅基因rpoB显著经历了基因重组事件;另外,基于Prim’s和goeBURST的进化分析表明,一半左右的肠道源发酵乳杆菌倾向于形成单独的分支,表明它们具有一定的宿主特异性,可能的原因是为适应肠道环境,这些发酵乳杆菌经历了有异于发酵食品生境的进化历程。     

5株植物乳杆菌生物学特性及安全性评价

通过对不同分离源的5株植物乳杆菌进行产酸、抑菌、耐酸耐胆盐、耐药性、溶血性、产生物胺能力测定,结果显示:5株菌的产酸及抑菌能力较强,差异显著（p<0.05）;耐酸性能较强,2 h的存活率在85.67%⁹8.00%,PBIL1-002与其他各菌株之间差异显著（p<0.05）;耐胆盐能力相对较弱,2 h的存活率在21.17%⁵1.20%,除PBIL1-002与PBIL1-006外,其余各菌株间差异显著（p<0.05）;5株菌均对链霉素和万古霉素耐药,PBIL1-009和PBIL1-018对复方新诺明耐药;PBIL1-006和PBIL1-009对庆大霉素耐药;菌株不具溶血性能;定性检测菌株产生物胺能力显示,PBIL1-009代谢产生精胺,PBIL1-018代谢产生精胺和酪胺。说明不同分离源的菌株特性及安全性有一定差异,生产应用时需选择生物学特性佳且无安全隐患的菌株。      

产CLA乳酸菌体内、体外抑菌活性的研究

采用体内和体外抑菌法研究产CLA乳酸菌对大肠杆菌、金黄色葡萄球菌和沙门氏菌的抑菌作用。体外抑菌实验表明,乳酸菌发酵上清液对大肠杆菌的抑制作用最强,对沙门氏菌和金黄色葡萄球菌的抑制作用相对较弱。体外研究还发现,乳酸菌发酵液在pH<5.0时,抑菌效果较好,并且具一定的热稳定性,对过氧化氢酶和蛋白酶的抗性较高。体内抑菌实验表明,该乳酸菌能够有效降低以上三种致病菌引起的小鼠死亡率,且体内抑菌效果随剂量的增加而增强。结论:产CLA乳酸菌在体内和体外均有较好的抑菌效果。      

In vitro and in vivo assessment of the effect of Laurus novocanariensis oil and essential oil in human skin

Laurus novocanariensis is an endemic plant from the Madeira Island forest that derives a fatty oil, with a strong spicy odour, from its berries that has been used for centuries in traditional medicine to treat skin ailments. This work aimed to investigate the effect of the application of both the oil and its essential oil on normal skin, to assess their safety and potential benefits. Diffusion studies with Franz cells using human epidermal membranes were conducted. The steady‐state fluxes of two model molecules through untreated skin were compared with those obtained after a 2‐h pre‐treatment with either the oil or the essential oil. Additionally, eleven volunteers participated in the in vivo study that was conducted on the forearm and involved daily application of the oil for 5 days. Measurements were performed every day in the treated site with bioengineering methods that measure erythema, irritation and loss of barrier function. Slightly higher steady‐state fluxes were observed for both the lipophilic and the hydrophilic molecule when the epidermal membranes were pre‐treated. Nevertheless, such differences had no statistical significance, which seems to confirm that neither the oil nor the essential oil impaired the epidermal barrier. Results collected with the Chromameter, the Laser Doppler Flowmeter and the visual scoring are in agreement with those established in the in vitro study. They indicate that the repeated application of the oil did not cause erythema, because the results observed in the first day of the study were maintained throughout the week. Application of the oil did not affect the skin barrier function, because the transepidermal water loss remained constant throughout the study. The stratum corneum hydration was slightly reduced on days 4 and 5. This work shows that both the oil and the essential oil were well tolerated by the skin and did not cause significant barrier impairment or irritation.     

Effects of natural compounds on microbial safety and sensory quality of Fior di Latte cheese, a typical Italian cheese

This work presents a preliminary study to assess the efficiency of plant essential oils as natural food preservatives in Fior di Latte cheese. Selected compounds were directly dissolved into Fior di Latte brine. Packaged Fior di Latte samples were stored at 10°C for about 6 d. The cell loads of spoilage and useful microorganisms were monitored to calculate the microbial acceptability limit. Results show that some tested compounds were not acceptable by the panel from a sensorial point of view. Most compounds did not affect the microbial acceptability limit value to a great extent, and only a few such as lemon, sage, and thyme markedly prolonged the microbial acceptability limit of the investigated fresh cheese. Moreover, the above active agents exerted an inhibitory effect on the microorganisms responsible for spoilage without affecting the dairy microflora.     

Interaction of probiotic Lactobacillus and Bifidobacterium strains with human intestinal epithelial cells: adhesion properties, competition against enteropathogens and modulation of IL-8 production

The human intestinal microbiota plays a pivotal role in human nutrition and health by promoting the supply of nutrients, preventing pathogen colonization and shaping and maintaining normal mucosal immunity. The depletion of the individual microbiota can result in a higher susceptibility to enteropathogenic bacteria infection. In order to reduce this risk, the use of food supplements containing probiotic bacteria has been recently addressed. In this paper, we investigate the protective role toward enteropathogen infection of probiotic strains belonging to Lactobacillus and Bifidobacterium. According to our experimental data, Lactobacillus acidophilus Bar13, L. plantarum Bar10, Bifidobacterium longum Bar33 and B. lactis Bar30 were effective in displacing the enteropathogens Salmonella typhimurium and Escherichia coli H10407 from a Caco-2 cell layer. Moreover, L. acidophilus Bar13 and B. longum Bar33 have been assessed for their immunomodulatory activity on IL-8 production by HT29 cells. Both strains showed the potential to protect enterocytes from an acute inflammatory response. These probiotic strains are potential candidates for the development of new functional foods helpful in counteracting enteropathogen infections.     

Ration formulations containing reduced-fat dried distillers grains with solubles and their effect on lactation performance,rumen fermentation,and intestinal flow of microbial nitrogen in Holstein cows

Sixteen multiparous lactating Holstein cows were used in 2 experiments to evaluate the effects of reduced-fat dried distillers grains with solubles (RFDG) on milk production, rumen fermentation, intestinal microbial N flow, and total-tract nutrient digestibility. In experiment 1, RFDG was fed at 0, 10, 20, or 30% of diet dry matter (DM) to 12 noncannulated Holstein cows (mean ± standard deviation: 89 ± 11 d in milk and 674 ± 68.2 kg of body weight) to determine effects on milk production. In experiment 2, the same diets were fed to 4 ruminally and duodenally cannulated Holstein cows (mean ± standard deviation: 112 ± 41 d in milk; 590 ± 61.14 kg of body weight) to evaluate the effects on rumen fermentation, intestinal flow of microbial N, and total-tract nutrient digestibility. In both experiments, cows were randomly assigned to 4 × 4 Latin squares over 21-d periods. Treatments (DM basis) were (1) control (0% RFDG), (2) 10% RFDG, (3) 20% RFDG, and (4) 30% RFDG. Feed intake and milk yield were recorded daily. In both experiments, milk samples were collected on d 19 to 21 of each period for analysis of milk components. In experiment 2, ruminal pH was measured; samples of rumen fluid, duodenal digesta, and feces were collected on d 18 to 21. Microbial N was estimated by using purines and DNA as microbial markers. Milk yield was not affected by treatment and averaged 34.0 ± 1.29 kg/d and 31.4 ± 2.81 kg/d in experiments 1 and 2, respectively. Percentage of milk protein tended to increase in experiment 1; estimates were 3.08, 3.18, 3.15, and 3.19 ± 0.06% when RFDG increased from 0 to 30% in the diets. However, milk protein concentration was not affected in experiment 2 and averaged 3.02 ± 0.07%. Percentage of milk fat was not affected and averaged 3.66 ± 0.05% and 3.25 ± 0.14% in experiments 1 and 2, respectively. Total ruminal volatile fatty acids and ammonia concentrations were not affected by treatment and averaged 135.18 ± 6.45 mM and 18.66 ± 2.32 mg/dL, respectively. Intestinal microbial N flow was not affected by treatment; however, purines yielded higher estimates of flow compared with DNA markers. When averaged across treatments, intestinal flow of microbial N was 303 and 218 ± 18 g of N/d, using purines and DNA as the markers. Dry matter, organic matter, neutral detergent fiber, and nonfiber carbohydrate digestibility tended to increase with increasing inclusion of RFDG. Results from these experiments indicate that dairy rations can be formulated to include up to 30% RFDG while maintaining lactation performance, volatile fatty acids concentration, and intestinal supply of microbial N.