Folate‐producing lactic acid bacteria from cow’s milk with probiotic characteristics

The probiotic potential of newly isolated lactic acid bacteria from cow’s milk was analysed and the efficacy of the selected isolates to produce folic acid was determined by microbiological assay. Two isolates, CM 22 and CM 28 were selected for folate production in skim milk medium and the net folate yield was 12.5 ng and 14.2 ng/mL respectively. The two isolates (CM 22 and CM 28) showed more than 98% similarity to Lactococcus subsp. cremoris and Lactococcus lactis subsp. lactis respectively by 16S rRNA sequencing.     

乳酸菌直投发酵剂培养与冷干条件的优化

采用响应面法对保加利亚乳杆菌(Lactobacillusbulgaricus)和嗜热链球菌的增菌(Streptococcusther-mophilus)培养基进行了优化,并且对其冻干保护剂进行了筛选,结果表明通过流加碱控制保加利亚乳杆菌的pH值为5.8,嗜热链球菌的pH值为6.4,培养15h,菌体的浓度分别达到1.24×109cfu/mL和8.05×108cfu/mL。离心收集到的菌体,在-70℃的冰箱先预冻3h,然后在冷阱温度-51℃、真空度9Pa冻24h,最终可以得到含活菌数为1.43×1010cfu/g的高活力酸乳发酵剂。     

乳酸菌的益生功能及作用机制研究进展

乳酸菌类益生菌是功能性食品的主要生理活性成分之一,其益生作用已经成为食品科学和临床医学领域的研究热点。本文就近年来乳酸菌改善乳糖不耐症、防治腹泻和消化性溃疡、提高机体免疫力等益生功能和作用机制的研究进展做一综述,并对研究前景提出展望,以期为我国乳酸菌的开发应用奠定基础。      

The viability of three probiotic organisms grown with yoghurt starter cultures during storage for 21 days at 4°C

This study investigated the viability of probiotic ( Lactobacillus acidophilus LA5, Lactobacillus rhamnosus LBA and Bifidobacterium animalis subsp . lactis BL-04) in milk fermented with Lactobacillus delbrueckii subsp . bulgaricus LB340 and Streptococcus thermophilus TAO (yoghurt – Y). Each probiotic strain was grown separately in co-culture with Y and in blends of different combinations. Blends affected fermentation time(s), pH and firmness during storage at 4°C. The product made with Y plus B. animalis subsp . lactis and L. rhamnosus had counts of viable cells at the end of shelf life that met the minimum required to achieve probiotic effect. However, L. acidophilus and L. delbrueckii subsp . bulgaricus were inhibited.     

Effect of different matrices on probiotic resistance to in vitro simulated gastrointestinal conditions

In this study, we evaluated the effect of different matrices (MRS, milk and milk with inulin) on the tolerance of probiotic strains (Lactobacillus acidophilus La‐5 and Bifidobacterium animalis subsp. lactis BB‐12) to simulated conditions similar to those found in the gastrointestinal tract. Both probiotic strains demonstrated a significantly lower viability after exposure to in vitro gastric and intestinal conditions, and B. animalis subsp. lactis BB‐12 showed higher survival during the test compared to L. acidophilus La‐5 in all tested matrices. Milk and inulin protected probiotics from in vitro gastrointestinal stress. These results suggest that it is critical to formulate the food matrix to be used as probiotic carrier.     

乳酸菌的适酸性调节

探讨了乳酸菌适酸机制有助于抗酸菌株的筛选、发酵过程中工序的优化以及培养基的优化等,进而大大提升发酵产品品质.对质子泵、产碱、细胞膜变化、大分子保护修复以及耐酸调节在内的适酸性调节机制进行了一一阐述.     

Screening of some potentially probiotic lactic acid bacteria for their ability to synthesis conjugated linoleic acid

Strains of potentially probiotic lactobacilli, propionibacteria, leuconostoc, lactococcus, enterococcus, and pediococcus, were tested for their ability to convert linoleic acid to conjugated linoleic acid (CLA). Growth and CLA production were followed during incubation for 48 h in reconstituted skim milk containing 0.2% lipolysed sesame oil. Lactococcus lactis subsp. lactis biovar diacetylactis and Leuconostoc mesenteroides subsp. mesenteroides gave the highest CLA production. Also, the effect of lipolysed oil concentration on the growth and CLA production of six strains were studied in medium containing 0.0–1% lipolysed oil. Leuconostoc mesenteroides subsp. mesenteroides and Lac. lactis subsp. lactis biovar diacetylactis gave maximum dienes in medium containing 0.6% and 0.8% lipolysed oil respectively.     

Assessment of the probiotic potential of lactic acid bacteria isolated from Minas artisanal cheese produced in the Campo das Vertentes region,Brazil

The microbiota of the Brazilian Minas artisanal cheese, made from raw milk, is not well known and may include probiotic bacteria. This study aimed to assess the in vitro and in vivo probiotic properties of the lactic acid bacteria isolated from these cheeses. Thirty‐six samples of the Lactobacillus/Pediococcus group were selected for in vitro investigation. Pediococcus acidilactici (PA2) and Lactobacillus plantarum (LP4) showed the best results and were tested for their ability to protect Salmonella Typhimurium orally infected mice. LP4 showed better probiotic potential than PA2 and allowed higher values of weight gain (P < 0.05). Thus, Lb. plantarumLP4 may have potential use as a probiotic in foods after future technological screening.     

乳酸菌细胞固定化发酵的研究进展

乳酸菌足能利用糖发酵产生乳酸的一类细菌,在食品、医药、工业、农业和科研等领域均有广泛的应用。本文综述了利用乳酸菌进行细胞固定化发酵生产乳酸、乳制品以及Nisin的国内外研究进展情况。并对乳酸菌固定发酵技术的应用前景进行了简要论述。     

Lactic acid bacteria and yeasts isolated from the starter doughs for Chinese steamed buns in Thailand

Isolation of lactic acid bacteria (LAB) and yeasts from the starter dough of Chinese steamed buns from four different commercial sources in Thailand was carried out. Thirty-one lactic acid bacteria and eight yeast strains were isolated. Total counts of LAB were from 1.8 × 10⁴ to 10⁸ colonies/g sample, whilst yeasts were very low from 10 to 2.3 × 10² colonies/g sample. The pH values of all starter doughs ranged from 3.36 to 3.52 and the Total Titratable Acidity (TTA) varied from 11.1 to 17.0 ml of 0.1 N NaOH/10 g dough. All LAB isolates were identified as Lactobacillus. The phenotypic characteristics were used to cluster all the LAB isolates into two major groups (Group A and Group B), with the B group subdivided into four groups. Phylogenetic analysis, based upon partial 16S rRNA gene sequences, showed that isolates of Group A, which all contained meso-diaminopimelic acid in their cell wall and produced dl-lactic acid, were closely related to Lactobacillus plantarum, whilst the strains of Group B that produced l-lactic acid were closely related to Lactobacillus casei. For yeasts, eight isolates based on the D1/D2 domain sequences of 26S rRNA were identified as Candida tropicalis, Pichia stipitis, Candida parapsilosis, Issatchenkia orientalis and Saccharomyces cerevisiae.     

Enhancement of survival of probiotic and non-probiotic lactic acid bacteria by yeasts in fermented milk under non-refrigerated conditions

The effects of yeasts on the survival of probiotic and non-probiotic lactic acid bacteria (LAB) were studied in fermented milk under non-refrigerated conditions (30 °C) with a view to develop ambient-stable fermented milk with live LAB. Five yeasts tested (Saccharomyces bayanus, Williopsis saturnus var. saturnus, Yarrowia lipolytica, Candida kefyr and Kluyveromyces marxianus) enhanced the survival of Lactobacillus bulgaricus (but not Streptococcus thermophilus) in a mixed yoghurt culture in yoghurt by ~ 10² to 10⁵-fold. Seven yeasts examined (Candida krusei, Geotrichum candidum, Pichia subpelliculosa, Kloeckera apiculata, Pichia membranifaciens, Schizosaccharomyces pombe and Y. lipolytica) improved the survival of Lactobacillus rhamnosus in fermented milk by ~ 10³ to 10⁶-fold. W. saturnus var. saturnus enhanced the survival of Lactobacillus acidophilus, L. rhamnosus (probiotic) and Lactobacillus reuteri by up to 10⁶-fold, but the same yeast failed to improve the survival of Lactobacillus johnsonii (probiotic), S. thermophilus and L. bulgaricus in fermented milk. These results provide definitive evidence that yeasts possess stability-enhancing effects on LAB and that the specific effects of yeasts on LAB stability vary with yeasts as well as with LAB. However, the molecular mechanism of such interaction of yeasts with LAB remains to be found.     

乳酸菌的分类鉴定方法的研究进展

近年来随着乳酸菌众多有益功能的开发,乳酸菌在食品、保健品等行业的应用越来越广泛。然而大部分乳酸菌菌种均无统一的标准鉴定方法,难于对该类产品进行质量控制,保证其安全性,故建立规范的乳酸菌标准鉴定方法势在必行。该文论述了目前国内外用于乳酸菌分类鉴定的方法。     

降胆固醇乳酸菌的筛选及其鉴定

对19株乳杆菌进行体外实验,研究它们在MRS-CHOL培养基中对胆固醇的降解量,进而分析各菌株降胆固醇的能力。结果表明,所有试验菌株均有降解培养物中胆固醇的能力,去除率在3.84%～42.28%之间。其中有2株试验菌对培养物中胆固醇的降解率大于40%,这2株菌对胆固醇的脱除效力也较高。这2株菌WE43-1-2和WE57-1经形态学、生理生化反应以及糖类发酵试验被鉴定为敏捷乳杆菌(Lactobacillus agilis)和干酪乳杆菌干酪亚种(Lactobacillus casei subsp casei)。     

清爽型褐色乳酸菌饮料配方研制浅析

通过实验确定清爽型褐色乳酸菌饮料配料过程中产生褐色的糖类和产生独特风味的发酵菌种,使产品具有特殊浅褐色颜色的同时,获得清爽良好的口感。     

广州市售酸奶中乳酸菌的耐药性评估

研究广州市售酸奶中乳酸菌对不同种类抗生素的药物敏感性。从市售酸奶中分离并鉴定乳酸菌,采用纸片扩散法检测分离菌株对18种抗生素的药物敏感性;E-test方法对耐药菌株进行最低抑菌浓度测定。从31份市售保质期内商标注册酸奶中分离鉴定出48株乳酸菌,其中25株嗜热链球菌(Streptococcus thermophilus)、20株保加利亚乳杆菌(Lactobacillus bulgaricus)、3株副干酪乳杆菌(Lactobacillus paracasei)。48株乳酸菌对卡那霉素、链霉素均耐药;对头孢他啶、头孢噻肟、红霉素均敏感;对环丙沙星、庆大霉素、万古霉素等呈现出不同程度的耐受性;79.2%(38/48)表现出多重耐药性;E-test分析表明,除了保加利亚乳杆菌MR10的MIC为256μg/mL以外,所有万古霉素耐药菌株对万古霉素的MIC均大于1024μg/mL。不同品牌酸奶分离菌株对抗生素具有不同的耐受性,均有多重耐受性出现,应加强其耐药性连续监测及安全评价。     

发酵蔬菜中乳酸菌抑菌性的研究

乳酸菌（Lactic Acid Bacteria）是一类能发酵碳水化合物产生乳酸的细菌，他广泛应用于发酵食品中，是发酵蔬菜中的有益菌群。乳酸菌的抑菌功能是通过产生各种代谢产物包括酸性物质、二氧化碳、过氧化氢和细菌素等来实现的。通过分析发酵蔬菜中微生物菌群结构的组成，介绍了乳酸菌对病原菌和腐败菌的抑制作用特点及作用机理，旨在为乳酸菌制品的加工、储藏提供理论依据，更好地将乳酸菌这一益生菌应用于各类食品加工的实践操作中。     

发酵蔬菜中乳酸菌抑菌性的研究

乳酸菌(Lactic Acid Bacteria)是一类能发酵碳水化合物产生乳酸的细菌,他广泛应用于发酵食品中,是发酵蔬菜中的有益菌群。乳酸菌的抑菌功能是通过产生各种代谢产物包括酸性物质、二氧化碳、过氧化氢和细菌素等来实现的。通过分析发酵蔬菜中微生物菌群结构的组成,介绍了乳酸菌对病原菌和腐败菌的抑制作用特点及作用机理,旨在为乳酸菌制品的加工、储藏提供理论依据,更好地将乳酸菌这一益生菌应用于各类食品加工的实践操作中。     

乳酸菌发酵剂高密度培养的研究

研究了乳酸菌生长繁殖的环境条件(温度、接种量、起始pH等)和培养基组成(氮源、碳源、缓冲盐等),优化确定了乳酸菌发酵剂的适宜培养条件为:起始pH值为6.5,培养温度为37℃,培养基配比为麦芽糖∶乳糖(1∶1)2%、牛肉膏1.0%、缓冲盐A0.5%、NaCl0.25%、MgSO40.1%,接种量4%,进一步探索了半连续法进行高密度培养,结合优化的培养条件,可使乳酸菌的液体发酵活菌密度至1.1×1012CFU/mL。     

降胆固醇乳酸菌的筛选、鉴定及生长特性

从香肠、腊肉、泡菜、酸奶等传统发酵食品中获得的42株乳酸菌,应用不同胆固醇源的高胆固醇MRS-broth测定其降胆固醇能力,从中筛选出降胆固醇能力较高的6株菌,分别为CM7,S9,P5,P9,Y1,P215菌株。其中P215菌株具有较好的耐酸性、一定的胆盐耐受力和较高胆固醇降解率。结合形态学、生理生化特性和16S rDNA序列同源性分析,P215菌株被鉴定为植物乳杆菌(Lactobacillus plan-tarum)。并研究了P215菌株在添加鸡蛋黄和化合物胆固醇的MRS-broth中的生长曲线、pH值变化及胆固醇降解率。结果表明,P215菌株在高胆固醇MRS中2 h后进入对数生长期,10 h后进入稳定期,22 h后逐渐进入衰退期。     

乳酸菌对发酵乳制品风味形成的影响

乳酸菌对发酵乳制品风味有决定性影响,发酵乳制品的风味物质主要是乳酸菌利用脂肪、碳水化合物和蛋白质等物质产生的。文章对乳酸菌代谢脂肪、糖、柠檬酸和氨基酸产生芳香物质的机理进行了综述。