鼠李糖乳杆菌LT22代谢产物抑菌实验研究

将鼠李糖乳杆菌LT22接种于发酵培养基,37℃培养48 h,离心、过滤除菌,滤液即为鼠李糖乳杆菌代谢产物(LRM).用金黄色葡萄球菌等6种菌作为指示菌,采用牛津杯双层平板定量扩散法对LRM进行体外抑菌试验.结果表明,LRM对6种指示菌有较强的抑菌活性,最大抑菌圈直径可达22.3mm,而与LRM相同pH值的乳酸、乙酸和盐酸溶液无抑菌作用;该抑菌活性物质耐热性强,不受过氧化氢酶、蛋白酶、木瓜蛋白酶、胰蛋白酶及pH值2～4变化的影响,但pH值变化到5～10时,抑菌活性却完全丧失.     

鼠李糖乳杆菌发酵液中水溶蛋白的提取及其抗氧化活性研究

采用硫酸铵沉淀法获得鼠李糖乳杆菌B10发酵液中水溶蛋白粗提物,并进行葡聚糖凝胶SephadexG-100柱纯化,分离得到不同的蛋白组分峰Ⅰ、峰Ⅱ和峰Ⅲ,分别对各组分DPPH自由基清除能力、清除超氧自由基(O2-·)和羟自由基(·OH)的能力及超氧化物歧化酶(SOD)和过氧化氢酶(CAT)的活性进行分析。结果表明,纯化前后各样品均对DPPH·有清除作用,其中纯化后的峰Ⅰ对DPPH·清除能力最强,峰Ⅱ、峰Ⅲ次之,均高于水溶蛋白粗提物;纯化后的峰Ⅰ对O2-·和·OH的清除能力最强,均高于5mmol/L的Vc溶液和水溶蛋白粗提物对O2-·和·OH的清除作用,峰Ⅱ和峰Ⅲ均未检测到对O-·和·OH的清除能力。     

干酪乳杆菌纯种发酵大豆乳培养基的优化调配

从益生菌乳制品中自行分离选育出的生长繁殖力强、发酵活力高的干酪乳杆菌(05-20)为试验菌株,研究了牛乳和蔗糖在大豆乳中的添加量对干酪乳杆菌在大豆乳中发酵的凝乳时间、凝乳时活菌数、pH值、滴定酸度及产品感官风味的影响,通过方差分析确定了发酵培养基中牛乳和蔗糖的最适添加量分别为20%和7%,完成了以大豆乳作为干酪乳杆菌最佳载体的初步探索,为进一步研制开发益生菌发酵大豆乳制品奠定了基础.     

Nonfermented ice cream as a carrier for Lactobacillus acidophilus and Lactobacillus rhamnosus

Efficiency of a nonfermented ice cream for delivering Lactobacillus acidophilus and Lactobacillus rhamnosus to consumers was evaluated. Both of the microorganisms survived at the populations of greater than 10⁷ CFU g^?1 during 12 weeks of storage at ?19 °C. Addition of the microorganisms had no significant effect on the overrun, viscosity, firmness and melting behaviour; it changed the acidity, pH and sensory properties of the finished product. Resistance to acid and sensitivity to bile of both bacteria were tested separately on fresh harvested cells before inoculation to ice cream and then on the frozen‐thawed cells after 12 weeks of cold storage in ice cream. Ice cream processing followed by cold storage reduced acid resistance of both bacteria at pH 2.5. Resistance to bile in L. rhamnosus was not affected in frozen‐thawed ice cream when compared to fresh cell, whereas resistance to bile in L. acidophilus appeared to be more susceptible to the process and cold storage.     

Dry sausage fermented by Lactobacillus rhamnosus strains

The ability of three probiotic Lactobacillus rhamnosus strains GG, E-97800 and LC-705 and one commercial Pediococcus pentosaceus starter strain (control) to produce dry sausage was studied. During the fermentation process the numbers of inoculated lactic acid bacteria increased from approx. 7 log10 to 8-9 log10 cfu/g and the pH values decreased from 5.6 to 4.9-5.0. The sensory test indicated that the dry sausages fermented by L. rhamnosus LC-705 were inferior to the control sausages. The presence of inoculated experimental strains as predominant organisms in the dry sausages was recognised on the basis of their genetic fingerprints by ribotyping. The concentrations of biogenic amines remained low during the ripening process. These results indicated that the studied Lactobacillus rhamnosus strains, especially strains GG and E-97800, are suitable for use as probiotic starter cultures in fermenting dry sausage.     

产共轭亚油酸鼠李糖乳杆菌的筛选与鉴定

从东北传统酸菜汁中筛选出具有产共轭亚油酸(CLA)能力的乳酸菌菌株15株,采用紫外分光度计法测定发酵液中共轭亚油酸产量,其中菌株A53.2的产量最高,在MRS培养基中添加0.4mg/mL亚油酸(LA),37℃发酵24h,CLA产量达14.91μg/mL。通过对菌体的形态特征和生化特性分析,并结合16SrDNA分子生物学以及系统发育分析鉴定菌株A53.2为鼠李糖乳杆菌。     

鼠李糖乳杆菌降解亚硝酸盐影响因素研究

该试验研究鼠李糖乳杆菌降解亚硝酸盐的影响因素.研究发现,鼠李糖乳杆菌降解亚硝酸盐的最适pH值是5.0～6.0,最适温度是40℃;培养基中碳源、氮源、酵母膏、金属离子成分分别为2%葡萄糖、0.5%大豆蛋白胨、0.4%酵母膏;添加Fe2+、Fe3+、Cu2+的亚硝酸盐降解效果明显;最适接种量3%;最适培养方式为动态培养.     

鼠李糖乳杆菌发酵及冻干保护的研究

对鼠李糖乳杆菌发酵性能和冷冻干燥存活率与保护剂、发酵时间和温度的关系进行了研究。利用液体发酵、紫外分光测量法、微量活菌计数法进行培养、测量。结果表明，鼠李糖乳杆菌发酵周期为12－16h；乳清粉和双歧因子对鼠李糖乳杆菌发酵产酸性能和细菌总数有定的影响。正交实验结果表明，10％乳清粉，15％脱脂奶粉，16h发酵时间的组合，冷冻干燥后存活的影响无显著性差异。结论：乳清粉和双歧因子在发酵后期会对鼠李糖乳杆菌的生长和发酵有促进作用可能是含糖量较高的原因。在冻干时，蛋白质（特别是酪蛋白）对细菌有保护作用。     

鼠李糖乳杆菌耐酸及胆盐能力研究

本实验对来源于婴儿粪便鼠李糖乳杆菌进行耐酸、耐胆盐能力表征及模拟胃液和模拟肠液实验。结果获得鼠李糖乳杆菌菌株B在pH1.8条件下,维持2h,活菌数达到107CFU/ml以上;在pH值为2.2以上的培养基中生长良好,而且随着时间的延长菌株的数量增加。在胆盐浓度在0.5%以下的MRS-broth培养基中鼠李糖乳杆菌B菌株维持4h,活菌数均达到108CFU/ml以上,而且随着时间的延长活菌数均有所增加。模拟胃液和模拟肠液实验结果表明该菌株能够有效通过胃环境,并能在肠道中繁殖。结果可见,鼠李糖乳杆菌B具有较强的酸的胆盐的耐受能力,符合微生态制剂和乳酸菌发酵功能食品菌种的要求。     

Hazelnut milk fermentation using probiotic Lactobacillus rhamnosus GG and inulin

Following the consumer demand of healthy vegetable products due to their interesting nutritional profiles and potential functionalities, the fermentation process of hazelnut milk with Lactobacillus rhamnosus GG and S. thermophilus was studied. The effect of different factors (glucose, inulin and inoculum contents) was analysed to ensure sufficient probiotic survivals in a minimum time. The shelf life of the optimised product was characterised in terms of its main physicochemical and quality parameters (probiotic survivals and sensory analysis). Results showed that the defined formulation allowed high probiotic survivals (≈10⁸ cfu mL^?1) throughout cold storage and >60% survived to the in vitro digestion process (≈10⁵ cfu mL^?1). Lactobacillus rhamnosus GG was no able to degrade inulin, which remained to exert health benefits in the host. The product was highly appreciated by the sensory panel during its shelf life despite the formation of a weak gel, which presented syneresis at the last storage time.     

真菌多糖对鼠李糖乳杆菌性质的影响

研究了不同质量浓度的真菌多糖对鼠李糖乳杆菌的影响。结果表明,质量浓度为15g/L的真菌多糖对鼠李糖乳杆菌的增殖效果最显著,其活菌数最大可达到3.08×1010mL-1,能够使发酵周期提前2～3h。其产酸能力得到明显的提高,并且此真菌多糖益生元较好地提高了鼠李糖乳杆菌的耐酸、耐胆盐的能力。     

鼠李糖乳杆菌乳饮料发酵工艺

对无稳定剂鼠李糖乳杆菌Lactobacillus rhamnose发酵乳饮料的发酵工艺进行优化。以L.rhamnose在不同碳源培养基中的发酵速度为评价指标,筛选出葡萄糖是其发酵的最适碳源。发酵时间、杀菌条件、发酵温度对发酵乳饮料的活菌数及沉淀率均有明显的影响。优化工艺参数为:杀菌条件115℃,15 min,发酵温度为37℃,发酵时间为84 h,按照此工艺制得的发酵乳饮料,活菌数达到8.5×108CFU/m L,沉淀率为1.1%。     

Antifungal activity of Lactobacillus paracasei ssp. tolerans isolated from a sourdough bread culture

Lactic acid bacteria were isolated from four different sourdough bread cultures previously investigated for antifungal activity. A total of 116 isolates were obtained and screened for antifungal activity against a battery of molds. The most inhibitory isolate obtained was identified by API 50 CHL and 16s ribosomal RNA genotyping and found to be Lactobacillus paracasei ssp. tolerans. This isolate completely inhibited the growth of Fusarium proliferatum M 5689, M 5991 and Fusarium graminearum R 4053 compared to controls in a dual agar plate assay.     

有抑菌功能的豆奶发酵剂Lactobacillus casei rhamnosus的选育

从15个茵株中筛选出抑茵作用好的Lactobacillus casei rhamnosus LCR 6013,该茵能使豆奶均匀凝乳,在MILS中的培养上清液对金黄色葡萄球茵有极好的抑制作用,抑茵圈直径 25～26 mm.该菌株依次用Nisin溶液、酸溶液和NaCl溶液驯化后,抑茵作用有所增加.驯化后的LCIL 719W在豆奶中高密度生长并有良好的稳定性.     

The Viability of Lactobacillus rhamnosus GG and Lactobacillus acidophilus NCFM Following Double Encapsulation in Alginate and Maltodextrin

Lactobacillus rhamnosus GG (LGG) and Lactobacillus acidophilus NCFM (LNCFM) were encapsulated in alginate microgel particles (microbeads) by a novel dual aerosols method. The encapsulated probiotics in microbead gel matrix were further stabilized in maltodextrin solids by either spray or freeze-drying to form probiotic microcapsule powders. The free cells of probiotics were also sprayed and freeze-dried in maltodextrin only without microgel encapsulation. After rehydration of microgel-encapsulated powder, gel particles regained their shape. There was no difference in the loss of viability between encapsulated and unencapsulated probiotics during spray drying or freeze-drying. For LNCFM, spray-dried bacteria with or without gel encapsulation exhibited less death (3.03 and 3.07 log CFU/g reduction, respectively) than those of freeze-dried bacteria (4.36 and 4.89 log CFU/g reduction, respectively) after 6 months storage at 4 °C. The same trend was also observed in spray-dried LGG without gel encapsulation which showed 5.87 log CFU/g reduction in viability after 6 months at 4 °C; however, freeze-dried LGG without gel encapsulation exhibited a rapid reduction in viability of 5.91 log CFU/g within just 2 months. Gel-encapsulated LGG which was freeze-dried exhibited less death (3.32 log CFU/g reduction) after 6 months at 4 °C. This work shows that spray drying results in improved subsequent probiotic survivability compared to freeze-drying and that alginate gel encapsulation can improve the survivability following freeze-drying in a probiotic-dependent manner.     

Biological reduction of aflatoxin B1 in yogurt by probiotic strains of Lactobacillus acidophilus and Lactobacillus rhamnosus

Food Science and Biotechnology - The present study was conducted to investigate the ability of two probiotic strains, L. acidophilus PTCC 1643 and L. rhamnosus PTCC 1637, to bind aflatoxin B1...     

Lactobacillus casei CRL 431 and Lactobacillus rhamnosus CRL 1224 as biological controls for Aspergillus flavus strains

The effect of two species of lactobacilli, Lactobacillus casei CRL 431 and Lactobacillus rhamnosus CRL 1224, on growth of different Aspergillus flavus strains was determined. A. flavus strains (Ap, TR2, or CF80) were grown in LAPTg broth at 37 degrees C for 7 days as a single culture and in association with L. casei CRL 431 or L. rhamnosus CRL 1224 at initial inoculum ratios of 1:1, 1:10, and 1:100. In most cases, the mixed cultures had a lower fungal growth and a lower pH than the control cultures. Mycelial dry weight was reduced to 73 and 85% using L. casei CRL 431 and L. rhamnosus CRL 1224, respectively. The pH decrease in mixed cultures when the fungal mycelial dry weight is reduced may play an important role in inhibition. The number of viable bacteria was variably affected by fungal growth. These results indicate that L. casei CRL 431 and L. rhamnosus CRL 1224 may be useful as potential biocontrol agent against A. flavus.     

鼠李糖乳杆菌的生物学特性及发酵性能研究

就鼠李糖乳杆菌 (Lactobacillusrhamnosus)的分离鉴定 ,在BL、AS、MRS液体培养基中的发酵性能 ,乳清粉、脱脂奶粉、海藻糖对该菌在冷冻干燥过程中的保护作用进行了初步研究 ,对该菌抑制E coli,Salmonella ,Shigella等致病菌的作用和与保加利亚乳杆菌、嗜热链球菌的混合发酵进行了探讨 ,为开发新型微生态调节剂提供了技术依据     

The protective effect of monosodium glutamate on survival of Lactobacillus rhamnosus GG and Lactobacillus rhamnosus E-97800 (E800) strains during spray-drying and storage in trehalose-containing powders

The use of trehalose as a means of preserving Lactobacillus rhamnosus GG (LGG) and L. rhamnosus E-97800 (E800) during spray-drying and the effects of incorporated monosodium glutamate (MSG) in the carrier medium on the survival rates during drying and storage were examined. E800 was more resistant to heat than LGG in 20%, w/w, trehalose; the d-values at 65 °C were 14 s and 5.1 s, respectively. An air outlet temperature of 65–70 °C was taken as optimal for the drying process, as the resultant moisture levels in trehalose containing these bacteria were 4.1% (w/w) and 3.79% (w/w) with corresponding viable counts of 3.65 × 10⁸ cfu mL^?1 and 1.80 × 10⁹ cfu mL^?1, respectively. The presence of MSG increased the final viable counts of LGG and E800 to 3.05 × 10⁹ cfu mL^?1 and 1.30 × 10⁹ cfu mL^?1, respectively. Survival of LGG and E800 remained constant at a minimum level of ～10⁸ cfu mL^?1 during storage at 25 °C in trehalose–MSG medium.