耐热型罗伊氏乳杆菌液态微胶囊的制备及其体外模拟消化特性

为了提高罗伊氏乳杆菌的耐热性,该研究以麦芽糊精与磷脂作为复合壁材,对其进行包埋处理形成罗伊氏乳杆菌液态微胶囊。结果表明：随磷脂、麦芽糊精浓度增加及乳化时间的延长,微胶囊的包埋率、EAI、ESI及电位绝对值呈先增加后减小的趋势（P<0.05）,平均粒径呈先减小后增加的趋势（P<0.05）。通过响应面设计得到该微胶囊最佳制取工艺：磷脂添加量14.83%（m/m）,麦芽糊精溶液质量分数15%（m/m）,乳化时间86.39 min,包埋率为99.11%。罗伊氏乳杆菌微胶囊热处理后其活菌数明显提高（P<0.05）。体外模拟消化试验显示,胃消化阶段,肠消化阶段活菌数随时间逐渐增多（P<0.05）,2 h后微胶囊活菌数达到1.85×108 CFU/mL。综上,由麦芽糊精、磷脂复合壁材制备的罗伊氏乳杆菌液态微胶囊包埋效果良好,提高了罗伊氏乳杆菌的耐热性和胃肠道存活率。研究结果为罗伊斯乳杆菌微胶囊的生产应用提供理论依据。     

Influence of sodium glycocholate on production of conjugated linoleic acid by cells of Lactobacillus reuteri ATCC 55739

ABSTRACT:  The possible influence of a bile salt on production of conjugated linoleic acid (CLA) by Lactobacillus reuteri ATCC 55739 was evaluated. Cells of the lactobacilli grown in MRS broth with and without linoleic acid (LA, 0.2%) were harvested and washed. The washed cells were added to buffer containing 0.2% LA and incubated 18 h at 37 °C. The cells, which had been grown without LA, transformed LA into CLA (mainly c9t11-C18:2) better than did those cells grown with it. When sodium glycocholate (0.3%) was added to the washed cell suspensions, about the same level of CLA was formed as in its absence regardless of whether or not the cells had been grown in broth supplemented with free LA. Thus, glycocholate that occurs in humans did not influence production of CLA by resting cells of the lactobacilli.     

罗伊氏乳杆菌的益生特性及安全性分析

本研究对一位128岁老人源罗伊氏乳杆菌进行了体外益生特性和安全性分析。采用模拟胃肠液对49株罗伊氏乳杆菌进行耐受筛选,得到了3株存活率都大于90.00%的菌株,分别是LT018、LT037、LT046。对上述3株罗伊氏乳杆菌进行表面特性、抑菌活性和安全性分析,结果表明,LT018具有较好的粘附繁殖能力(疏水性为54.65%,凝集性为67.20%),菌株的表面疏水性和凝集性之间存在负相关(R=-0.869);非酸性抑菌活性物质在酸性条件下才发挥作用,它们的上清液对大肠埃希氏菌、金黄色葡萄球菌、蜡样芽胞杆菌、伤寒沙门氏菌和福氏志贺氏菌均有较明显的抑制作用,其中对金黄色葡萄球菌的抑制效果最佳,抑菌圈直径均大于15.00 mm;它们都不具有产生物胺有害物质的活性,除氯霉素外,对其他4种临床常用抗生素(红霉素、四环素、庆大霉素、万古霉素)敏感。综合上述结果,认为这些菌株具有良好的开发潜力。     

Spray-drying microencapsulation using whey protein isolate and nano-crystalline starch for enhancing the survivability and stability of Lactobacillus reuteri TF-7

Decrease of survivability and stability is a major problem affecting probiotic functional food. Thus, in this study, Lactobacillus reuteri TF-7 producing bile salt hydrolase was microencapsulated in whey protein isolate (WPI) or whey protein isolate combined with nano-crystalline starch (WPI-NCS) using the spray-drying technique to enhance the survivability and stability of probiotics under various adverse conditions. Spherical microcapsules were generated with this microencapsulation technique. In addition, the survival of L. reuteri TF-7 loaded in WPI-NCS microcapsules was significantly higher than WPI microcapsules and free cells after exposure to heat, pH, and simulated gastrointestinal conditions. During long-term storage at 4, 25, and 35 °C, WPI-NCS microcapsules could retain both survival and biological activity. These findings suggest that microcapsules fabricated from WPI-NCS provide the most robust efficiency for enhancing the survivability and stability of probiotics, in which their great potentials appropriate to develop as the cholesterol-lowering probiotic supplements.     

罗伊氏乳杆菌培养基优化及其生长代谢研究

罗伊氏乳杆菌的MRS 培养基是富培养基,简化培养基组分,优化培养基组成和培养条件是微生物工业化培养的重要基础。本实验在传统MRS 培养基基础上,首先对氮源进行单因素优化,然后采用Plackett-Burman 和中心组合试验设计对影响罗伊氏乳杆菌CG001 生长的MRS 培养基和培养条件进行筛选优化,并在最优条件下研究该菌的生长代谢情况。结果表明：酵母膏质量浓度、葡萄糖质量浓度、硫酸锰质量浓度和温度是影响菌体质量浓度的4 个关键因素;经响应面法分析确定该菌的最优培养条件为：酵母膏质量浓度20g/L,葡萄糖质量浓度20g/L,醋酸钠质量浓度7g/L,柠檬酸铵质量浓度1g/L,磷酸氢二钾质量浓度3g/L,硫酸镁质量浓度0.2g/L,硫酸锰质量浓度为0.23g/L,吐温-80 质量浓度1g/L,初始pH6.2,培养温度38.6℃,最终菌体质量浓度达0.984g/L,相对优化前提高1.102 倍。发酵罐中菌体生长曲线呈S 型,4～12h 菌体处于对数生长期,之后趋于平衡,葡萄糖的代谢与菌体的生长速率相对应。     

热激处理罗伊氏乳杆菌(Lactobacillus reuteri)增强其抗逆性的研究

为了研究热激对益生菌抗逆性的影响,本研究以罗伊氏乳杆菌(Lactobacillus reuteri)为实验对象,以存活率、抗性基因表达为指标,采用平板计数法研究了热激处理对罗伊氏乳杆菌在后续高温和高盐逆境下存活率提高的效果,并用q PCR方法检测基因表达水平。结果表明:热激预处理(40℃,30 min)罗伊氏乳杆菌之后,能显著(p<0.05)提高其在后续高温(45、48、51℃),高盐(0.1%、0.3%、0.7%Na Cl,m/v)以及氧化逆境(H2O2,0.3、0.6、1.2 mmol/L)下的存活率。此外,热激预处理(40℃,30 min)还能显著(p<0.05)提高巯基过氧化物酶(thiol peroxidase)和抗氧化蛋白(peroxiredoxin)的转录表达水平。说明热激处理通过提高罗伊氏乳杆菌抗逆基因的表达,增强其对于后续逆境的抗性。该研究结果为益生菌的规模化应用提供了理论依据。      

冷胁迫对冷冻干燥罗伊氏乳酸杆菌细胞膜流动性的影响

以DPH(1,6-二苯基-1,3,5-己三烯)为荧光探剂,优化了测定罗伊氏乳酸杆菌细胞膜流动性的条件,其最佳测定条件为:激发波长360nm,发射波长430nm,菌浓度OD0.8,30℃孵育时间为20min。同时研究冷胁迫处理对冷冻干燥存活率。细胞活力及细胞膜流动的影响,研究表明冷胁迫能改善乳酸菌的冷冻干燥存活率,同时在一定的条件下,冻干后细胞的流动性也有所改变,说明经过一定的冷胁迫处理后,增加了细胞的抗性,从而提高细胞的冷冻存活率。     

具有降胆固醇功能的罗伊氏乳杆菌的筛选及其益生作用

为获得具有较强降胆固醇功能的益生菌株,试验从内蒙古呼伦贝尔满洲里通达牧场制作的奶豆腐中筛选分离菌株,并采用邻苯二甲醛法测定菌株降胆固醇的能力,从中选出降胆固醇能力强的菌株,通过形态学鉴定、生理生化及16S rDNA对菌株进行鉴定,并测定了其耐受酸、胆盐和胃肠液的能力。结果筛选分离出5株具有降胆固醇功能的菌株,其中一株菌对胆固醇降解能力最强,降解率达50.60%,经鉴定此株菌为罗伊氏乳杆菌（Lactobacillus reuteri）,将其命名为HCS02-001（CGMCC No. 19746）;经对酸、胆盐及胃肠液的耐受试验,该株菌在pH 3.0和pH 2.0的环境中培养17 h后存活率分别为86.80%和85.52%;在0.30%、0.50%的胆盐浓度环境中培养17 h后存活率分别为97.42%和95.17%;在人工胃液中作用3 h,存活率为96.74%;在人工肠液中作用4 h,存活率高达98.41%。该研究筛选出了一株具有较好降胆固醇功能的罗伊氏乳杆菌（Lactobacillus reuteri）,其具有较强的耐受酸、胆盐环境和胃肠液的能力,对关于降胆固醇功能方面的产品研究开发具有重要意义。     

Lactobacillus reuteri IMAU10240增殖培养基及高密度培养工艺优化

Lactobacillus reuteri IMAU10240(L.reuteri IMAU10240)是一株具有潜在益生特性的乳酸菌,为实现产业化应用,对其培养工艺进行优化以提高其活菌数。本研究以MRS培养基为基础,通过单因素筛选试验、正交试验和响应面优化试验对该菌株的培养基以及培养条件进行优化。通过实验确定L.reuteri IMAU10240最适培养基:蔗糖100.00 g/L,大豆蛋白胨13.25 g/L,酵母粉8.84 g/L,酵母蛋白胨13.25 g/L,Na_2HPO_4 19.85 g/L,柠檬酸2.58 g/L,MnSO_4·5H_2O 0.12 g/L,MgSO_4·7H_2O 0.40 g/L,甘油2.76 g/L,吐温-80 1.00 g/L,L-半胱氨酸盐酸盐0.50 g/L。初始pH 6.5,通入氮气37℃恒pH 5.5培养7~8 h。利用优化好的配方工艺进行5 L/50 L/200 L发酵罐的小试及中试试验,验证L.reuteri IMAU10240的发酵工艺,活菌数为7.57×10~9 CFU/mL,冻干菌粉活菌数为2.59×10~(11) CFU/g,可以进行生产验证。     

Effect of reuterin,produced by Lactobacillus reuteri on the surface of sausages to inhibit the growth of Listeria monocytogenes and Salmonella spp.

Reuterin is a bacteriocin produced by some strains of Lactobacillus reuteri. The strain used in this study was isolated from raw milk from a dairy farm nearby Ankara. Beef sausage is a long years produced bratwurst style meat product in Turkey, as well as in some other countries in the Mediterranean region. Sausages are produced by raw meat; sometimes lactic starter cultures are added or spontaneous fermentation is employed. The production and storage conditions of the product promotes the growth of Listeria monocytogenes and Salmonella spp. Although nitrate is added as an antimicrobial substance against many pathogens, sometimes however nitrate application is not preventive enough on the surface because of the natural film around the sausages. Since most of the contaminations take place at post production steps, pathogenic growth is more effective on the surface of the sausages in refrigerated conditions. In this study, reuterin was applied to the surface of the sausages in order to prevent the growth of these two pathogens along with nitrate used as an additive in the product. Reuterin has inhibited the growth of L. monocytogenes considerably but not of Salmonella spp. on the surface of the sausages.     

罗伊氏乳杆菌LT018高密度培养生长因素的研究

罗伊氏乳杆菌LT018是经过筛选的源自巴马百岁老人粪便中的优良益生菌株。为优化出适合其高密度生长的培养基,本研究以TPY为基础培养基,采用单因素方法确定增值培养基的成分为胰蛋白胨、酵母粉、麦芽糖、柠檬酸、柠檬酸钠、西红柿汁和L-半胱氨酸。采用Plackett-Burman实验设计方法得出胰蛋白胨、柠檬酸和L-半胱氨酸对菌株LT018的生长影响显著,继而进行最陡爬坡实验,通过RSM确定显著因子的最优组合为:胰蛋白胨含量12.13 g/L,柠檬酸0.4 g/L,L-半胱氨酸0.6 g/L。在上述培养基的基础上,利用单因素方法确定培养最佳条件为:接种量为4%,温度为37℃,初始p H为7.0,静置培养。此时该菌株的活菌数可达到7.13×1010cfu/m L,是未优化前的10.7倍。      

产Reuterin罗伊氏乳杆菌的定向筛选及其生物学特性

依据菌株宿主适应性特点,从健康家禽新鲜粪便中定向筛选具有开发潜力的罗伊氏乳杆菌.经16S rDNA序列分析和pduC基因筛查,获得3株产抗菌物质Reuterin的罗伊氏乳杆菌,对其耐受模拟胃肠道环境、抗生素敏感性、甘油发酵上清液抑菌活性及肠上皮细胞黏附能力等生物学特性进行系统评价.结果 表明,罗伊氏乳杆菌WLRE01、...     

人工神经网络结合遗传算法优化保护剂提高罗伊氏乳杆菌抗冻性能

为提高新筛选的罗伊氏乳杆菌LTR1318冷冻干燥过程中的抗冻性能,通过单因素试验先筛选出影响乳酸菌冻干存活率的4个主要因素:脱脂乳、谷氨酸、低聚果糖和山梨糖醇.再利用Box-Behnken试验设计不同保护剂组合下的菌株冻干存活率为训练集和测试集,构建径向基函数人工神经网络模型,模型拟合度可达0.9844.结合遗传算法对...     

罗伊氏乳杆菌发酵液中具有降胆固醇能力蛋白的分离、纯化和鉴定

罗伊氏乳杆菌DSM122460无细胞上清发酵液（cell-free supernatant,CFS）具有较高的胆固醇移除能力,经初步鉴定有效成分为蛋白质。通过超滤浓缩、硫酸铵分级沉淀、DEAE Sepharose F.F阴离子交换层析进一步对该活性成分进行分离纯化。纯化后,其比活力达到61.6 U/mg,纯化倍数为32.4。经SDS-PAGE检测,样品达到电泳级纯,分子量约为60 ku。通过质谱鉴定初步认定该活性蛋白为一假设蛋白,其功能尚待进一步研究。      

具有抑制腐败菌能力的罗伊氏乳杆菌筛选及在酸乳生产中的应用

以青霉菌作为酸乳腐败菌筛选具有抑制该菌能力的罗伊氏乳杆菌,并通过排除实验确定优势菌株的主要抑菌物质,再将优势菌株作为辅助发酵剂用于酸乳发酵,并对酸乳进行理化性质和感官品质的评定以及优势菌株在酸乳中生物防腐作用的探讨。结果表明,罗伊氏乳杆菌CICC6121是具有抑制青霉菌能力的优势菌株,其无细胞上清液中抑制青霉菌的主要活性成分为罗伊氏乳杆菌素;罗伊氏乳杆菌CICC6121在酸奶发酵过程中不会对保加利亚乳杆菌和嗜热链球菌产生拮抗作用,且所生产的酸乳与未接种CICC6121时的酸乳在理化性质和感官品质方面几乎无差别,在21 d的低温贮藏过程中,能够抑制酸乳中青霉菌的生长,减少因污染而造成酸乳的腐败变质。     

Influence of pH on the Formation of Glucan by Lactobacillus reuteri TMW 1.106 Exerting a Protective Function Against Extreme pH Values

Lactobacillus reuteri TMW 1.106, a dominant type II sourdough bacterium, produces glucan from sucrose in vitro and in situ. Exopolysaccharides positively affect the texture and mouth feel of foods and their in situ production in fermented foods could be an alternative to the addition of hydrocolloids from plants or non-GRAS microorganisms. The aim of this study was to elucidate a probable function of the EPS for the bacterium. Lb. reuteri TMW 1.106 harbors two glucosyltransferases, Gtf106A and Gtf106B and produces a dextran. Gtf106B exhibited hydrolysis but no transferase activity. Enzymatic production of dextran with the heterologously expressed, N-terminally truncated ΔN Gtf106A was highest at a pH of 4.0, whereas dextran formation in pH static fermentations was optimal between pH 4.7 and 5.4. The dextran synthesised at these pH values had the highest molecular mass (1.2 × 10⁷) and 15% α–(1–4) linkages. A protective effect of this EPS on Lb. reuteri TMW 1.106 against low pH, explaining the low pH-production maximum, could be demonstrated through the delay of cell death.     

一株罗伊氏乳杆菌的生物学特性研究

研究了一株完达山乳业和润盈生物菌种研究项目组分离的罗伊氏乳杆菌LR-G100的耐胃酸、耐胆盐、降胆固醇和抑制肠道有害菌的生物学特性。结果表明,罗伊氏乳杆菌在pH值为2.5～4.5条件下,具有较强的生存能力;在胆盐质量分数为0.1%～0.5%环境中,活菌数能保持在106mL-1以上;在反应16 h后,同化胆固醇百分率能达到50%以上;对肠道有害菌的抑制效果也非常显著。     

瑞士乳杆菌MG9-2微胶囊的制备工艺优化及其性能分析

以乳蛋白为壁材,利用内源乳化法制备瑞士乳杆菌MG9-2微胶囊,对其进行工艺优化,并比较添加不同钙盐作为交联剂(CaCl_2和CaCO_3)对微胶囊性能的影响。结果显示制备瑞士乳杆菌MG9-2微胶囊的最佳工艺参数为:乳化搅拌速率800r/min、水油比1∶10、脱脂乳质量浓度0.35g/mL、钙盐浓度1.5mol/L。在此条件下以CaCO_3、CaCl_2为交联剂制得MG9-2微胶囊的包埋率分别为(78.4±3.6)%和(75.7±4.9)%,无显著性差异。但与CaCl_2为交联剂制得的MG9-2微胶囊相比,CaCO_3制得的微胶囊粒径较小,表面较致密、形状较规则、分散性较好,且具有较好的肠液释放性和耐胃酸性。结果表明,以CaCO_3为交联剂在室温制备瑞士乳杆菌MG9-2微胶囊的工艺简单且性能较好。     

4种多糖益生元对鼠李糖乳杆菌微胶囊稳定性的影响

为提高鼠李糖乳杆菌（Lactobacillus rhamnosus GG,LGG）的稳定性,采用复合凝聚法制备LGG微胶囊,探究菊糖、低聚果糖、普鲁兰多糖和水苏糖4种益生元对LGG微胶囊性能的影响,并结合扫描电镜和差示扫描量热仪分析微胶囊的微结构和热稳定性。结果表明：益生元对LGG微胶囊的性能均有积极影响。模拟胃肠液处理后,菊糖活菌数存活率最高,达9.5(lg(CFU/g));水苏糖对LGG微胶囊在胆盐和高温下的保护能力最强,75℃、30 min后活菌数达8.7(lg(CFU/g));水分活度0.75条件下低聚果糖的加入提高了LGG微胶囊的贮藏稳定性;差示扫描量热分析结果表明益生元提高了LGG微胶囊的热稳定性,水苏糖的微胶囊熔融温度达172℃,但低聚果糖降低了LGG微胶囊的熔融温度;扫描电镜分析表明添加益生元后微胶囊结构没有变化。本研究为后续添加益生元对LGG微胶囊性能的影响研究提供理论基础。     

Isolation and characterization of Lactobacillus species having potential for use as probiotic cultures for dogs

ABSTRACT:  The need to control pathogenic microorganisms in the intestinal tract of dogs is a growing concern. There is interest in using probiotics such as species of Lactobacillus to help control canine intestinal infections. For successful use as a probiotic, the bacterial species should be of canine intestinal origin since these species exhibit host specificity. Serial dilutions of freshly voided dog feces were plated on Lactobacillus selection (LBS) agar to isolate the cultures. Isolates were identified based on Gram stain, catalase test, and fermentation patterns using API 50 CH kits. All potential isolates were compared for bile resistance based on relative ability to grow in broth containing 0.3% Oxgall, the ability to inhibit Salmonella Typhimurium in associative broth cultures, and the production of reuterin. Of the lactobacilli isolated, Lactobacillus reuteri was the dominant species. However, some cultures of L. acidophilus also were isolated. We found variations among the isolates of L. reuteri and L. acidophilus with respect to bile tolerance. In general, isolates of L. reuteri appeared to be more bile resistant than were isolates of L. acidophilus . There were also variations in the ability to inhibit growth of S. Typhimurium. Some isolates of L. reuteri produced reuterin while others did not.