中国传统乳制品中乳杆菌的益生菌潜力评估

目的：评估从中国传统乳制品中分离出的9株乳杆菌的功能及其益生菌潜力。 方法：从中国传统乳制品中分离纯化得到乳杆菌菌株,测试了它们的益生菌潜力,如溶血活性和抗氧化活性等。 结果：所有分离的乳杆菌均可耐受低pH值（pH 2.0、2.5和3.0）和高胆盐条件（0.3％,0.5％和1％）。 测试了分离的乳杆菌对10种抗生素的敏感性,结果表明,所有分离株对万古霉素均没有抗性,另一方面,大多数分离株对青霉素,氨苄青霉素,链霉素和四环素具有抗性。 所有乳杆菌对HT-29细胞具有优异的粘附能力,其值介于10.4％-39.0％之间,并且对DPPH自由基（清除率50.4％-80.4％）和超氧阴离子自由基具有出色的抗氧化活性（清除率17.5％-44.4％）。 另外,所有分离的乳杆菌均可以极大降低胆固醇含量（19.1-65.8 μg / mL）,且没有任何溶血性。结论：从中国乳制品中分离出的乳杆菌具有作为各种产品中益生菌的潜力。     

益生菌LGG的益生功效及在乳制品中的应用

LGG(ATCC53103)是一种专利的鼠李糖乳杆菌,由两位美国教授从健康人体内分离而得,也是目前全球研究最多的益生菌之一。功能性方面,LGG具有显著的平衡和改善肠道菌群、预防和治疗腹泻、提高机体免疫力、预防过敏、结合并排除毒素、预防龋齿等功能。此外,作为一种益生菌,LGG还具有耐胃酸、耐胆汁、可定殖于人体肠道、产品保质期内活菌数保持恒定等优点。LGG的应用范围十分广泛,主要包括食品和医药品。在乳制品中主要应用酸奶、牛奶、新鲜干酪、硬质干酪、婴儿食品、乳饮料等产品中。     

益生菌的功效与潜在危害

过去20年里,益生菌被广泛应用于食品中,尤其是发酵乳品中。在筛选益生菌时,其安全性、功能性和加工特性是必须考虑的方面。益生菌对免疫活性宿主是有益的,但是对免疫缺陷宿主,却可能产生危害。一些益生菌与条件感染有关,并且还有传递抗抗生素基因的危险。     

Selection of Lactobacillus strains from fermented sausages for their potential use as probiotics

A rapid screening method was used to isolate potentially probiotic Lactobacillus strains from fermented sausages after enrichment in MRS broth at pH 2.5 followed by bile salt stressing (1% bile salts w/v). One hundred and fifty acid- and bile-resistant strains were selected, avoiding preliminary and time-consuming isolation steps. Strains were further characterized for survival at pH 2.5 for 3 h in phosphate-buffered saline and for growth in the presence of 0.3% bile salts with and without pre-exposure at low pH. Twenty-eight strains showed a survival >80% at pH 2.5 for 3 h; moreover, most of the strains were able to grow in the presence of 0.3% bile salts. Low pH and bile resistance was shown to be dependent on both the species, identified by phenotypic and molecular methods, and the strain tested. This is the first report on the direct selection of potentially probiotic lactobacilli from dry fermented sausages. Technologically interesting strains may be used in the future as probiotic starter cultures for novel fermented sausage manufacture.     

乳源抗菌物质对益生菌生长的影响

含益生菌的乳制品研究开发是一种发展趋势,而天然乳源抗菌组分对这些益生菌的影响尚缺乏系统性研究。综述了4种主要的乳源抗菌物质(免疫球蛋白、乳铁蛋白、乳过氧化物酶、溶菌酶)对益生菌生长的影响及其抗菌机理研究进展。     

The occurrence and growth of yeasts in dairy products

Yeasts were isolated, identified and enumerated from 161 samples of retail dairy products. Highest yeast populations (up to 10⁶–10⁷ cells/g) were found in yogurt and cheese samples while lower counts occurred in samples of pasteurized milk, cream, butter and ice cream. Candida famata, Kluyveromyces marxianus, Candida diffluens and Rhodotorula glutinis were the most frequency isolated species. The growth of these and other species was demonstrated during the refrigerated storage of cream, butter and cheese samples and by their inoculation and incubation in milk and yogurt samples. The predominance and growth species was probably related to their production of protein and fat hydrolysing enzymes and the ability to grow at 5°C.     

益生菌抗癌功能及作用机制研究进展

益生菌在许多方面发挥了健康作用,然而与益生菌整肠功能、免疫调节功能等研究比较深入的益生功能相比较,其抗癌机制不太明确,抗癌功能颇受争议。本文综述动物实验和流行病学调查结果,支持益生菌具有抗癌功能的观点。目前对益生菌抗癌机制了解不多,其作用可能不是由单因素的机制来实现的,而是由包括直接作用和间接作用几种因素在内综合作用的结果。直接作用包括菌体本身或其活性代谢产物对致突变物的结合或降解作用,间接作用就是通过调节肠道菌群及其代谢酶活性、调节机体免疫功能、调节宿主相关的酶活力来起到抗癌作用。      

两株乳杆菌益生特性的体外研究

从健康个体口腔中分离得到了两株乳酸菌，经API细菌鉴定系统鉴定分别为植物乳杆菌Lactobacillus plantarum HO-69与Lactobacillus plantarum HO-160，并对两株植物乳杆菌的特性进行了研究。抑菌试验表明，两株菌的代谢产物具有较好的抑菌活性；两株菌对于人工消化液具有良好的耐受性，HO-69生长的最高胆汁质量分数为0．4％，HO-160为0.3％；两菌均具有较高的表面疏水性与酸碱电荷。     

Lactobacilli isolated from chicken intestines: potential use as probiotics

Lactobacillus strains were tested for their in vitro probiotic properties. Cell surface hydrophobicity was found to be very high for Lactobacillus fermentum subsp. cellobiosus and Salmonella Gallinarum; high values could indicate a greater ability to adhere to epithelial cells. Studies on Lactobacillus animalis indicated relative cell surface hydrophobicities smaller than those of L. fermentum subsp. cellobiosus and L. fermentum. L. animalis and Enterococcus faecalis were able to coaggregate with L. fermentum subsp. cellobiosus and L. fermentum, respectively, but not with Salmonella Gallinarum. After mixed-culture studies for determining suitable growth behavior, the pair of strains L. animalis plus L. fermentum subsp. cellobiosus was selected for an attempted challenge against Salmonella Gallinarum. Double and triple mixed-culture studies indicated that selected lactobacillus strains were able to retain their beneficial characteristics in the presence of Salmonella Gallinarum such as presence of lectins, production of antimicrobial compounds, and ability to grow and compete. The selected microorganisms can be considered as potential ingredients for a chicken probiotic feed formulation intended to control salmonellosis and also improve poultry sanitation.     

The technology of probiotics

One important task of the Fair CT96-1028 project (Demonstration of Nutritional Functionality of Probiotic Foods) has been to demonstrate the possibility of producing, on a pilot scale, probiotic dairy foods acceptable to European consumers. In the project, different Lactobacillus spp. and Bifidobacterium spp. strains were shown to be suitable for probiotic organisms. Culture concentrates were produced by standard methods, and showed high cell concentrations and good survival during storage at low temperatures. The starter cultures were used in producing several different probiotic dairy foods. Under certain conditions probiotic strains may be used as the sole fermenting agent in milk. However, in many cases use of a support culture is preferable. Probiotic dairy products were shown to have good organoleptic properties, and the survival of the probiotic organisms was excellent during the shelf life of the products.     

Application of in vitro methods for selection of Lactobacillus casei strains as potential probiotics

Probiotics have established their efficacy as dietary adjuncts providing benefits to consumers, but the selection of probiotics before incorporation in diet requires close scrutiny in the form of in vitro as well as in vivo tests. The present study was undertaken to check different in vitro characteristics of seven Lactobacillus casei strains. The characteristics studied include acid and bile tolerance, adhesion and cell surface hydrophobicity, antimicrobial effect on common pathogens and cholesterol reduction. All strains were able to resist pH 3 for 3 h, though resistance to pH 2 was exhibited by NCDC 17, C1 and Y strains only. NCDC 63 and VT strains were able to tolerate 1% and 2% bile concentrations for 12 h. There was wide variation in ability of strains to adhere to isolated rat epithelial cells. The index was highest for C1 at 66%. The electron microscopic adhesion studies on the stainless steel chips did not reveal any specific attachment to surfaces by any of strains. The hydrophobic character for octane was highest for strain C1 at 54.06% and lowest for strain C2 at 4.65%. The ability to antagonize common pathogens was observed in all strains but this activity was attributed to production of organic acids and no specific compound caused the inhibitory effect. The cholesterol reducing ability varied not only for strains but also for time of incubation. NCDC 17 showed maximum reduction in cholesterol level after 48 h of incubation with buffalo plasma as the source of cholesterol. Overall there existed variations in different strains with respect to different characters of significance to be a probiotic.     

Novel isolates of lactobacilli from fermented Portuguese olive as potential probiotics

The purpose of this work was to screen for and characterize the potential probiotic features of strains of lactic acid bacteria isolated from Galega cultivar fermented olives, to eventually develop an improved probiotic food from plant origin. From 156 isolated strains, 10 were acid – and bile salt tolerant, and exhibited survival rates up to 48%, following simulated digestion. All strains exhibited auto- (4–12%) and co-aggregation features (≥30%), as well as hydrophobicity (5–20%) and exopolysaccharide-producing abilities, while no strain possessed haemolytic capacity or ability to hydrolyse mucin. Antibiotic resistance, oleuropein degradation, proteolytic activity and antimicrobial activity were strain-dependent features. Overall, 10 strains – belonging to Lactobacillus plantarum and Lactobacillus paraplantarum, appear to possess a probiotic value.     

二株嗜热链球菌益生特性的体外研究

对嗜热链球菌ST1和嗜热链球菌KS1的部分益生性及功能特性进行了研究。考察了ST1和KS1对酸和胆盐的耐受性,结果表明,ST1和KS1在pH值为3.0条件下培养3h的存活率分别为67.17%和67.49%,在pH值为4.0或质量分数为0.3%胆盐环境中仍可以生长,表现出较高的存活力。通过抑菌实验表明ST1和KS1可以抑制常见的致病菌金黄色葡萄球菌、大肠杆菌、鼠伤寒沙门氏菌和福氏志贺氏菌。在对抗生素敏感实验中,ST1对其中的3种抗生素有耐药性,而KS1对6种抗生素有耐药性。研究还发现ST1和KS1还具有较高的降胆固醇的能力,胆固醇的去除率分别为65.14%和74.49%。     

两株具有潜在益生作用的人源链球菌的安全性评价

对分离于健康儿童口咽部的2株对金黄色葡萄球菌等常见致病菌具有广谱拮抗作用的甲型链球菌菌株1-4和4-2的安全性进行评价,为其作为呼吸道益生菌产品的研发和制备提供安全性依据.通过给予SPF级小鼠口服含有菌株1-4和4-2不同剂量的菌液的急性毒性实验以及耐药性的测定,观察动物是否出现死亡,急性毒性体征,细菌移位生长等情况....     

Genetic effects on dairy calf growth

Objectives were to establish growth patterns for weight and height in dairy calves from birth to 90 d and to estimate appropriate genetic parameters. Measurements were 7943 body weights and 7005 wither heights of 752 calves. Represented over 12 yr were three breeds, 348 dams, and 115 sires; data resulted from designed calf nutrition experiments. Sources of variation considered in various least squares analyses of variance were breed, sire in breed, calf in sire in breed, sex of calf, treatment-year category, and several interactions. Repeatabilities of weights and heights between birth and 90 d were .64 and .88; heritabilities were .22 and .30; genetic and phenotypic correlations were .53 and .73. A regression equation was estimated for each calf. From these 752 equations, heritabilities of initial weight, initial height, and rates of growth in weight and height were .53, .50, .44, and .19. Genetic correlations were .81; -.07; -.05; .26; .14; .84. Selection schemes for these traits in dairy cattle should consider that although weights and heights at birth and thereafter are highly and positively correlated genetically, as are gains, birth measurements and gains to 90 d may be uncorrelated.     

The relation between temperature and growth of bacteria in dairy products

The effect of temperature on the growth of psychrotrophs in dairy products has been studied using the ‘square root’ and Arrhenius models. The square root model has been shown to accurately predict temperature effects on the growth of several psychrotrophs in a number of dairy products. The formula can be applied for individual bacteria regardless of growth medium. This was not true for the Arrhenius equation. In this case, the apparent activation energy for growth (μ) was dependent on source of isolate and growth medium. For isolates from pasteurized cream, μ values were lower during growth in double cream than those obtained during growth in full-fat milk. This was due to shorter generation times at lower temperatures when these isolates were grown in double cream.Temperature-growth parameters were similar for bacteria grown in pasteurized as well as UHT products.     

Development of an Oriental-style dairy product coagulated by microcapsules containing probiotics and filtrates from fermented rice

The objectives of this study were to microencapsulate both probiotics and culture filtrates by spray drying to maintain enzyme activity and probiotic viability during storage. Thus, probiotics and culture filtrates from lao-chao were microencapsulated by spray drying with various outlet air temperatures, and the milk-clotting activity, survival of probiotics and physical properties of the microcapsules were determined. The end purpose was to create easy-to-use probiotic Kou Woan Loa cultures. In the near future, manufacturing probiotic Kou Woan Loa could be carried out by simply mixing milk with 5% microcapsules and waiting for 1 h for coagulation, which would be time saving and convenient. The present study has shown that microencapsulation of Lactobacillus acidophilus BCRC 14079, Bifidobacterium longum BCRC 14605 and culture filtrates from lao-chao by spray drying could provide a good protection for both milk-clotting enzymes and probiotics. The average of microcapsules size and density was 10 µm and 1.68 g/cm³, respectively. An increase in the microencapsulation efficiency of microcapsules and lower water activity was found when the outlet air temperature was raised. However, the survival of L. acidophilus and B. longum was reduced as the outlet air temperature increased. The numbers of probiotics were maintained above the recommended therapeutic minimum (10⁷ cfu/g) throughout storage.