双歧杆菌模拟胃肠环境中抗性的研究

采用PYG培养基,模拟胃肠环境,即低pH值(1．5—4．5),高胆汁酸盐(9．1％-0．4％)对青春双歧杆菌进行抗性研究。同时对肠道致病性大肠埃希菌、福氏志贺菌和金黄色葡萄球菌拮抗性以及对氨苄青霉素、庆大霉素、卡那霉素和氯霉素的耐药性进行研究。结果表明,青春双歧杆菌在pH4．5时有较强的生存能力,4h活菌效可达10^7CFU／m1以上。且能在含0．1％-0．4％的胆汁盐中存活,在0．1％-0．2％时4h活菌总数可达10^5CFU／m1以上。同时对致病性大肠埃希菌、福氏志贺菌和金黄色葡萄球菌具有明显的抑菌作用,且对庆大霉素中度敏感,对氨苄青霉素、卡那霉素和氯霉素有耐受性。     

重组干酪乳杆菌在模拟消化环境中生存性能的研究

目的 探讨重组干酪乳杆菌Lactobacillus casei 393在模拟胃肠道环境中的存活能力.方法 人工模拟胃肠道环境,即人工胃液（pH=1.5～4.5）、人工肠液、胆汁（质量浓度0.3～3.0 g/L）和高盐（质量浓度40～90g/L）.结果 重组干酪乳杆菌在pH为2.5～4.5的人工胃液中具有较强的生存能力,3 h活菌数仍达108/ml;在人工肠液中经过不同时间的作用后,重组干酪乳杆菌显出生长趋势;在0.3%的胆汁环境作用8 h仍有存活,且能耐受7%NaCl浓度的高渗环境.结论 实验为干酪乳杆菌Lactobacillus casei 393能否作为益生菌制剂在胃肠道中发挥作用提供了理论基础.     

嗜酸乳杆菌抑菌特性的研究

目的：对从婴儿肠道中分离出来的两株嗜酸乳杆菌的抑菌特性进行研究。方法：采用MRS培养基。结果：嗜酸乳杆菌对致病性大肠埃希菌、金黄色葡萄球菌以及炭疽杆菌有明显的抑菌作用。37℃培养24h抑菌圈大小均在15mm以上。结论：该菌是肠道中的益生菌。     

平菇浸汁促进嗜酸乳杆菌生长的研究

对平菇浸汁可促进嗜酸乳杆菌的生长进行了初步研究。结果表明,平菇浸汁对嗜酸乳杆菌在还原脱脂乳中的生长具有明显的促进作用,添加5％～10％的平菇浸汁,可大大缩短嗜酸乳杆菌生长的世代时间,提高其产酸速率;在37℃下1Oh的培养,其中活菌数的含量较对照组大大提高,可达108/mL。     

胆汁酸盐和低pH值对乳酸菌活性的影响

本文比较了几种乳酸菌对胆汁酸盐的耐受性和ｐＨ值的残活能力。研究结果表明,在０．２％的ＭＲＳ或ＢＭ培养基上,婴儿双歧杆菌的生长速率受到的抑制最小,依次为嗜酸乳杆菌、保加利亚乳杆菌和嗜热链球菌。胆汁酸盐对其生长的完全抑制浓度分别为１．５％、１．２％、０．５％和０．３％。在ｐＨ３时,嗜热链球菌活菌数量降低较为明显,在ｐＨ２时,在３７℃１ｈ过程中,婴儿双歧杆菌活菌数量基本不变;嗜酸乳杆菌在３７℃２０ｍｉｎ后,活菌数量迅速降低;保加利亚乳杆菌数量在３７℃２０ｍｉｎ时几乎为零。     

两岐双岐杆菌菌株制剂的研究——Ⅱ.两岐双岐杆菌及其和嗜酸乳杆菌、粪链球菌干燥菌粉胶囊的制备

用两岐双岐杆菌发酵液和嗜酸乳杆菌、粪链球菌发酵液经离心沉淀、真空干燥等步骤制备成混合干燥菌粉,其每克活菌数含量达10^7-8。经室温存放3个月后,活菌数仍可在10^6-7/g以上,在冰箱中存放则时间更长。这种菌粉具有较好的稳定性和实用价值。     

猪肠道乳杆菌的筛选及其生物学特性研究

目的从健康仔猪肠道中筛选到用于研制微生态制剂的优良乳杆菌株。方法本研究选用乳杆菌选择培养基LBS、MRS从健康仔猪肠道分离到67株乳杆菌,对其染色镜检、生化试验和耐酸、耐胆汁、耐高温、抑菌活性及动物安全性等生物学特性进行初步研究。结果从其中筛选到3株嗜酸乳杆菌,均能耐受pH3．0的酸度、0．8％～1．0％的牛胆盐和60℃的高温,其代谢产物对猪肠道致病性大肠埃希菌和猪沙门菌具有抑制作用,且对小白鼠无致病性。结论3株嗜酸乳杆菌符合益生菌的要求,可作为猪用益生素制剂的候选菌株。     

一种能同时富集沙门菌、大肠杆菌和金黄色葡萄球菌的增菌培养基

研究设计出一种能同时富集培养沙门菌、大肠杆菌和金黄色葡萄球菌的缓冲盐水肉汤(buffed saline broth,BSB),主要组分和含量为:蛋白胨10g、牛肉膏3g、磷酸氢二钠9g、磷酸二氢钾1.5g、添加剂50g、蒸馏水定容至1000mL,pH7.2。将1cfu/mL的上述3种菌同时分别接种到97mLBSB、蛋白缓冲水、乳糖肉汤、营养肉汤、大肠杆菌肉汤、氯化镁孔雀绿增菌液、7.5%氯化钠肉汤增菌培养基中,37℃增菌18h。结果表明BSB能使这3种菌以相对一致的速度增殖,分别达到106、106、107cfu/mL,并且多重PCR能同时分别扩增沙门菌invA基因284bp、大肠杆菌phoA基因622bp和金黄色葡萄球菌nuc基因484bp的特异性条带。相反,其他几种培养基则不能同时协调增殖上述3种菌。这些结果表明,BSB有较好的应用前景。     

利用乳清培养基生产乳品发酵剂的研究

通过测试保加利亚乳杆菌和嗜热链球菌在乳清培养基中的生长能力,以期获得新型乳品发酵剂工业用培养基。试验结果表明:研制的pH值内控型乳清培养基缓冲能力强,增殖效果佳:嗜热链球菌经42℃培养3h后的活菌数达到0.29×109CFU/mL,培养6h后的活菌数达到0.42×109CFU/mL。在此基础上流加20%氨水恒定pH值,保加利亚乳杆菌和嗜热链球菌的活菌数达到了1.85×109CFU/mL和3.65×108CFU/mL,分别是不加缓冲液培养的7倍和3.5倍。     

嗜酸乳杆菌产细菌素生物学特性的研究

嗜酸乳杆菌在MRS培养基中培养得到的细菌素经30、60、90、121℃处理20min后,活性几乎不变,对以金黄色葡萄球菌为代表的革兰阳性菌、大肠埃希菌为代表的革兰阴性菌有明显的抑制作用,Tricine—SDS—PAGE和不同pH值抑菌实验测定结果证明,嗜酸乳杆菌细菌素是一组低分子量,并在pH2—4时有抑菌作用的活性物质。     

一株降血压功能乳酸菌在模拟胃肠环境中抗性的研究

目的研究具有降血压功能乳酸菌DM9057株对pH、胆汁盐、胃蛋白酶及胰蛋白酶的耐受性。方法以MRS为基础培养基,模拟胃肠环境。结果 DM9057在pH2~3、胆汁盐浓度0.1%~0.3%、胃蛋白酶0.592~1.482μg/mL和胰蛋白酶14.24~72.32 U/g的条件下,37℃培养4 h,活菌数均能达到107CFU/mL以上。结论乳酸菌DM9057能顺利通过胃肠道,达到促进健康的作用。     

益生乳杆菌的筛选及特性研究

根据对优良益生菌的要求,从健康乳猪肠道中分离筛选到13株乳杆菌,其中嗜酸乳杆菌3株、干酪乳杆菌1株、链状乳杆菌1株、发酵乳杆菌8株。所选菌株能耐受1.0％的牛胆盐,对 pH3.0的酸度有较强的抵抗力,并能抑制常见致病菌,对小白鼠安全无毒,是制备益生素的优良菌种。     

一株广谱抑菌活性乳酸菌的筛选及特性研究

【目的】从贵州剑河采集的传统自然发酵豆酱中分离筛选具有广谱抑菌效果的乳酸菌,并进行肠道益生特性的研究。【方法】通过抑菌试验分离筛选得到菌株DJ-04,对其进行人工胃肠液耐受性、胆盐耐受性和渗透压耐受性的研究,并对其进行生理生化鉴定和16S r RNA鉴定。【结果】菌株DJ-04对大肠杆菌、沙门氏菌、金黄色葡萄球菌、志贺氏菌和铜绿假单胞菌的生长有很好的抑制作用;在p H值为2.5的人工胃液中处理3 h活菌数达到107 CFU/m L以上;在人工肠液中处理3 h活菌数达到108 CFU/m L以上,对人工胃肠液表现出良好的耐受性。能耐受一定浓度的牛胆盐,在质量浓度0.2 g/100 m L的牛胆盐环境中活菌数可达到107 CFU/m L;具有较高的渗透压耐受能力,在Na Cl质量浓度为10 g/100 m L的液体MRS中培养24 h后,活菌数仍在107 CFU/m L以上。经鉴定,DJ-04为植物乳杆菌。【结论】植物乳杆菌DJ-04具有良好的人工胃肠液耐受性以及耐胆盐和耐渗透压能力,具有肠道益生菌的潜能。     

Antimicrobial activity of Sesbania grandiflora flower polyphenol extracts on some pathogenic bacteria and growth stimulatory effect on the probiotic organism Lactobacillus acidophilus

Polyphenolic extracts (PE) of edible flower of Sesbania grandiflora were tested to evaluate its antimicrobial effect against some common pathogenic bacteria and growth promoting property against probiotic organism Lactobacillus acidophilus. The antimicrobial activity of S. grandiflora flower PE against selected pathogens was evaluated using both in vitro and in situ methods. In vitro studies suggested that PE has inhibitory effect against Staphylococcus aureus, Shigella flexneri 2a, Salmonella Typhi, Escherichia coli and Vibrio cholerae. The gram-positive organism S. aureus was the most sensitive organism to PE and minimum inhibitory concentration (MIC) was found to be 0.013 mg/mL where as the MIC of PE against V. cholerae was the highest (0.25 mg/mL). On the other hand PE showed growth promoting effect on the common probiotic bacterium L. acidophilus. The major finding was that S. grandiflora PE induced a significant biomass increase of L. acidophilus grown in liquid culture media. PE showed reduction of S. aureus growth in food (fish) during storage at 10°C. High performance liquid chromatography analysis showed that rutin, a major flavonoid of the PE diminished in the culture medium MRS broth with the growth of L. acidophilus.     

模拟人体胃肠道环境筛选益生乳杆菌

【目的】筛选具有益生特性的乳杆菌作为保健型酸奶的候选菌株。【方法】从健康人肠道和奶豆腐中分离筛选出耐受人工胃液的乳杆菌,对其进行体外益生特性(人工胃肠液耐受性、胆盐耐受性、抑菌活性及胆固醇降解能力)研究。【结果】从在乳杆菌分离培养基上有溶钙圈的41株菌株中筛选出5株耐酸、耐人工胃液较强的菌株,经16S rR NA基因测序鉴定,其中3株为乳杆菌,分别命名为植物乳杆菌Lp MT-3、植物乳杆菌Lp MT-5和唾液乳杆菌LsA F-7。在人工胃液中3株菌的耐受力均强于商品化的对照菌株LGG(鼠李糖乳杆菌GG);转入肠液4 h后直至26 h,Lp MT-5存活率基本稳定在45%左右,仅次于LGG。胆盐浓度为0.10%时,3株乳杆菌的耐胆盐能力均强于LGG;胆盐浓度为0.20%时,Lp MT-3和LsA F-7仍能存活。3株乳杆菌均具有抑菌活性,对粪肠球菌的抑制最明显,其次是金黄色葡萄球菌,对大肠杆菌、沙门氏菌的抑制作用较差。3株乳杆菌对胆固醇的清除效力依次为Lp MT-3LpM T-5Ls AF-7;清除率依次为Ls AF-7Lp MT-3LpM T-5。【结论】筛选出3株适应人体胃肠液环境、耐胆盐、抑菌及降胆固醇活力强的乳杆菌,可作为进一步开发新的益生菌产品和保健型酸奶的菌株。     

Antagonistic activity against pathogenic bacteria by human vaginal lactobacilli

This study attempted to isolate lactobacilli strains from healthy vaginal ecosystem to search for a new effective antibacterial probiotic strain. The strains were identified and characterized for their probiotic properties including bile salt and acid tolerance, growth at acidic pH, their ability to utilize protein, starch, and lipid, the production of hydrogen peroxide and bacteriocin as well as their antibiotic resistance patterns. The antibacterial activity of the culture supernatant of these strains were tested against a wide range of Gram-positive and Gram-negative pathogenic bacteria including Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae. Salmonella typhi, and Salmonella typhimurium. None of the strains inhibited the growth of Gram-negative bacteria. Contrastly, the culture supernatant of strain L 22, identified as Lactobacillus reuteri, significantly inhibited all of the clinical isolates of methicillin-resistant S. aureus (MRSA). The antibacterial effect of the selected strain L 22 was further investigated. In the presence of L 22, the bacterial growth was assessed in vitro by viable bacterial counting. The numbers of viable cells were significantly lower in L 22-containing broth than those in the control by 6h. This finding clearly demonstrates that strain L 22 can produce an anti-MRSA effect. The antibacterial ability of the strain L 22 was fundamentally attributed to their bacteriocin production which can cause both cell inhibition and cell death.     

The assumed assimilation of cholesterol by Lactobacilli and Bifidobacterium bifidum is due to their bile salt-deconjugating activity.

To study the mechanism of the propsed assimilation of cholesterol, we cultured various strains of Lactobacillus acidophilus and a Bifidobacterium sp. in the presence of cholesterol and oxgall. During culturing, both cholesterol and bile salts were precipitated. Because of bacterial bile salt deconjugation, no conjugated bile salts were observed in either the culture fluids or the pellets. During incubation, the cell count and optical density decreased. The degree of precipitation of bile salts and of cholesterol was dependent on the culture conditions. If L. acidophilus RP32 was cultured under acidifying conditions, the degree of precipitation of deconjugated bile salts was higher than if the pH was maintained at 6.0. Under acidifying conditions, cholesterol was coprecipitated with the bile salts, whereas in pH-controlled cultures, no coprecipitation of cholesterol was observed. From control experiments with different mixtures of bile salts, it appeared that coprecipitation of cholesterol during culturing was a result of formation of deconjugated bile salts, which have a decreased solubility at pH values lower than 6.0. It is concluded that the removal of cholesterol from the culture medium by L. acidophilus RP32 and other species is not due to bacterial uptake of cholesterol, but results from bacterial bile salt-deconjugating activity.     

降胆固醇乳酸菌的筛选和分析比较

目的比较7株乳酸菌各项生理特性,筛选高效、安全降解胆固醇的益生菌株,为后期开发应用奠定基础。方法对选定菌株依次进行体外降胆固醇、胆盐水解酶(BSH)活力、人工胃肠液及胆盐耐受性、细胞粘附性能的测定和比较,并分析抗生素耐药性和抑制病原菌活性,最后利用16S rRNA基因测序确定细菌种属。结果不同菌株各项生理指标存在差异。其中菌株ZL-2、JQI-7和PC-26的BSH酶活分别为0.010、0.015和0.030 U,可高效清除体外胆固醇,3株菌体外降解胆固醇率在58%以上;并且耐酸、耐胆盐,具备较好的HT--29细胞粘附性,不存在抗生素耐药性,可有效抑制大肠埃希菌、金黄色葡萄球菌、铜绿假单胞菌和阴沟肠杆菌生长。结论菌株ZL-2、JQI-7和PC-26满足降胆固醇益生菌株的生物学特性,可用于进一步研究和开发。     

两株乳酸杆菌益生菌特性的研究

对两株乳酸杆菌作为益生菌的特性进行分析。采用人工胃液、人工肠液,及体外培养人结肠癌细胞株HT-29,模拟 上消化道环境,检测候选菌株L.acidophilus1.1878和L.rhamnosus1.120对上消化道环境的耐受性和粘附性;以琼脂扩散打孔 法,检测候选菌株SCS对4种常见肠道致病菌的抑菌能力。结果表明,两株候选菌株可耐受pH>3.0的人工胃液,及0.2%的 胆盐浓度;光镜观察L.acidophilus1.1878、L.rhamnosus1.120粘附于HT-29细胞边缘,平均4.5～7个/细胞,扫描电镜观察 L.acidophilus1.1878、L.rhamnosus1.120粘附于HT-29细胞表面的刷状缘,且细胞表面结构完整;对4种肠道致病菌的抑菌 圈直径均在12mm以上。证明实验观察的两株乳酸杆菌具有较好的耐酸、耐胆盐及粘附、抑菌特性,符合益生菌的标准。