弱后酸化瑞士乳杆菌的筛选及发酵特性研究

[目的]在大健康背景下,发酵乳凭借其优良的营养和保健功能备受青睐.后酸化是发酵乳在贮存、运输和销售等过程中活性乳酸菌继续代谢产酸导致的,严重影响产品的感官品质,降低菌株的存活率.本文通过筛选弱后酸化的瑞士乳杆菌,改善发酵乳的后酸化问题.[方法]本研究以瑞士乳杆菌L551为出发菌株,硫酸新霉素为筛选压力,筛选弱后酸化的瑞...     

棒状腐败乳杆菌Lc7的生物学特性及益生作用

【目的】对分离自健康成人粪便样本的棒状腐败乳杆菌(Loigolactobacillus coryniformis)Lc7进行分类学鉴定和益生潜力评估。【方法】基于16SrRNA基因和基因组核心基因构建系统发育树,对Lc7进行分类学鉴定;通过耐酸和胆汁酸盐、粘附、抗氧化和抑菌实验,以及溶血、明胶酶活性和抗菌药物敏感性实验,评估Lc7的益生特性。同时,构建小鼠溃疡性结肠炎模型,评估Lc7的体内抗炎潜力。【结果】Lc7鉴定为L. coryniformis,在酸和胆汁酸盐的连续作用下,Lc7的存活率为70.17%。Lc7对HT-29细胞的粘附指数为56.33 CFU/cell,其自聚集和疏水性分别为80%和40%;Lc7对福氏志贺菌和鼠伤寒沙门菌等7个常见致病菌均有较强的抑制能力;对1,1-二苯基-2-苦基肼(1,1-diphenyl-2-picryl-hydrazyl,DPPH)和羟自由基(hydroxyl radicals,·OH)的清除率分别为91.70%和48.53%;Lc7无溶血现象和明胶酶活性,对选取的大多数抗生素均敏感。在小鼠结肠炎实验中,Lc7干预组小鼠结肠长度明显长于模型组(...     

乳杆菌在发酵乳饮料中的应用

为了制备更优质的乳酸菌饮料,本论文主要以鼠李糖乳杆菌、瑞士乳杆菌、副干酪乳杆菌、嗜酸乳杆菌四种典型的乳酸杆菌为研究菌种,详细分析它们在乳品发酵过程中pH、酸度变化,货架期内的活菌数变化以及代谢产生的有机酸种类和耐胃酸的能力,以确定乳杆菌在乳饮料中应用的最优条件,分析其应用于乳饮料中的可行性。本文为乳杆菌在乳饮料中的应用提供了参考依据。     

短乳杆菌与植物乳杆菌的发酵特性

【背景】目前对于酸菜发酵的研究主要关注点是植物乳杆菌(Lactobacillus plantarum),有关短乳杆菌(Lactobacillus brevis)在酸菜方面的研究报道很少。【目的】为了挖掘短乳杆菌的发酵性能并开发酸菜发酵剂,将2株短乳杆菌分别与1株植物乳杆菌进行组合并发酵酸菜,分析短乳杆菌对酸菜发酵品质的影响。【方法】分别测定短乳杆菌与植物乳杆菌的单菌株生长产酸性能、耐酸性及亚硝酸盐降解力,并将两菌种组合后发酵酸菜,分析1-7d内酸度、乳酸菌活菌数、亚硝酸盐含量及酸菜质构特性的变化趋势。【结果】相较于短乳杆菌Lb-9-2,短乳杆菌Lb-5-3的生长和产酸速率较慢、酸耐受力较弱,但其亚硝酸盐降解力较强。两株短乳杆菌分别与植物乳杆菌Lp-9-1组合后产酸力显著增强,并在3 d时达到最低pH值(约3.10);植物乳杆菌Lp-9-1的添加使酸菜中总体乳酸菌生长延迟,在5 d时达到最高活菌数;组合菌种的样品中亚硝酸盐含量在1-7 d内变化较为平缓,前5天内两个组合之间差异不显著;接种乳酸菌会降低酸菜硬度和弹性,发酵3d时Lb-5-3/Lp-9-1组合的硬度最大,感官评价得分最高。【...     

鼠李糖乳杆菌LV108及其发酵乳免疫调节作用的比较

目的 探讨鼠李糖乳杆菌LV108及其发酵乳对免疫抑制小鼠免疫功能的调节作用.方法 将BALB/c小鼠随机分为5组,每组10只,即空白组(正常小鼠)、模型组(免疫抑制小鼠)、药物组(免疫抑制小鼠食物中添加左旋咪唑)、LV108菌悬液组(免疫抑制小鼠食物中添加LV108菌悬液)和LV108发酵乳组(免疫抑制小鼠食物中添加L...     

棒状腐败乳杆菌Lc7对高脂血症仓鼠的降脂及其肠道菌群调节作用

【背景】高脂血症是心血管疾病的主要危险因素,其与肠道菌群的变化密切相关。乳酸菌等益生菌可通过调节肠道菌群结构发挥降脂功能。【目的】研究棒状腐败乳杆菌(Loigolactobacillus coryniformis) Lc7对高脂血症仓鼠血脂和肠道菌群的影响。【方法】通过饲喂高脂饲料构建仓鼠高脂血症模型,灌胃L. coryniformis Lc7菌悬液,干预6周后检测仓鼠血脂水平、血清炎症因子和脂多糖水平,观察肝组织和附睾脂肪组织的病理变化,采用16S rRNA基因扩增子测序分析盲肠内容物中的肠道菌群。【结果】L. coryniformis Lc7干预显著降低了高脂血症仓鼠血清总胆固醇(P<0.001)、甘油三酯和低密度脂蛋白胆固醇(P<0.05)的水平、升高了血清高密度脂蛋白胆固醇的水平(P<0.001)、降低了血清白细胞介素-1β (P<0.05)、白细胞介素-6 (P<0.01)和脂多糖(P<0.05)的水平,减轻了高脂饮食引起的肝组织损伤和附睾脂肪组织脂肪堆积,改善了肠道菌群的多样性和结构,降低了厚壁菌门与拟杆菌门相对丰度的比值(P<0.05),升高了颤杆菌克属和拟杆菌属等肠道有益菌的相对丰度,降低了螺杆菌属和Negativibacillus的相对丰度,螺杆菌属的相对丰度与总胆固醇浓度呈正相关(P<0.01)。【结论】L. coryniformis Lc7可改善仓鼠脂质代谢紊乱,调节肠道菌群,缓解高脂血症。提示L. coryniformis Lc7可以作为预防和治疗高脂血症的候选菌株。     

双歧杆菌乳杆菌三联活菌片对幽门螺杆菌根治后消化道不良反应的改善作用

探讨加用双歧杆菌乳杆菌三联活菌片对临床四联疗法根除幽门螺杆菌(H.pylori)过程中患者消化道不良反应的改善作用。

选择2019年1月至2020年1月在昆明医科大学第二附属医院门诊就诊的100例H.pylori感染患者, 分为益生菌组和正常组, 各50例。全部患者通过四联疗法根除H.pylori后, 益生菌组患者继续加用双歧杆菌乳杆菌三联活菌片治疗, 对结果进行分析。

2组患者使用含有铋剂的四联疗法根除H.pylori后效果满意。益生菌组患者不良反应发生率低于正常组(25.5% vs 47.5%;χ²=11.023, P=0.001)。

益生菌可减轻四联疗法根除H.pylori后消化道不良反应, 根除H.pylori过程中加用益生菌的时机尚待进一步探讨。

     

发酵乳杆菌AR497改善DSS诱导的小鼠炎症性肠病

本实验主要探究发酵乳杆菌AR497对DSS诱导的小鼠炎症性肠病的影响。发酵乳杆菌AR497在低pH、高胆盐浓度、高渗透压等极端条件下仍具有良好的生长能力,对大部分抗生素敏感;在C57BL/6J小鼠中研究其对由葡聚糖硫酸钠(DSS)诱导的结肠炎的缓解作用,发酵乳杆菌AR497处理后抑制小鼠体重减少,降低疾病活动指数,上调紧密连接蛋白基因Claudin 3,ZO-1和E-cadherin 1的表达。实验结果表明发酵乳杆菌AR497具有优良的生物学特性并可通过保护肠道屏障从而缓解DSS诱导的结肠炎。     

乳杆菌发酵上清对耐药白假丝酵母生物膜的作用

目的 研究德氏乳杆菌(Lactobacillus delbrueckii,L.delbrueckii)和发酵乳杆菌(Lactobacillus fermentum,L.fermentum)发酵上清液对3株耐氟康唑白假丝酵母临床分离株CA3、CA6、CA8生物膜形成和分散的作用。 方法 通过MIC试验,确认3株白假丝酵母临床分离株对氟康唑耐药;用96孔板构建体外白假丝酵母生物膜;用棋盘法分别检测L.delbrueckii、L.fermentum发酵上清液与氟康唑联用对3株白假丝酵母的作用;用XTT法对生物膜形成量进行定量分析;检测L.delbrueckii、L.fermentum发酵上清液与氟康唑联用对白假丝酵母时间-生长曲线的影响;显微镜拍照检测L.delbrueckii、L.fermentum发酵上清液单独和氟康唑联用对白假丝酵母生物膜形态的影响;平板培养法检测L.fermentum发酵上清液对白假丝酵母黏附作用的影响。 结果 CA3、CA6、CA8三株临床分离菌株对氟康唑耐药,MIC浓度均为8 μg/mL。L.delbrueckii与L.fermentum发酵上清液与氟康唑联用对3株耐药型白假丝酵母的生物膜形成与分散均未表现出协同作用,且发酵上清液与氟康唑联用效果不如发酵上清液单独处理效果好,L.fermentum发酵上清液对生物膜的分散作用较L.delbrueckii发酵上清液强。L.fermentum发酵上清液抑制白假丝酵母的初始黏附。 结论 L.delbrueckii、L.fermentum发酵上清液单独应用时均对耐氟康唑白假丝酵母生物膜的形成与分散有干预作用,与氟康唑联用时未表现出协同作用,抑制耐药白假丝酵母生物膜的作用可能与抑制菌丝形成和起始黏附有关。     

Production of D(-)-lactic acid from cellulose by simultaneous saccharification and fermentation using Lactobacillus coryniformis subsp. torquens

D(–)-Lactic acid was produced from cellulose by simultaneous saccharification and fermentation (SSF) in media containing cellulolytic enzymes and Lactobacillus coryniformis subsp. torquens ATCC 25600 at 39 °C and pH 5.4, yielding 0.89 g D(–)-lactic acid g^–1 cellulose at a mean volumetric productivity of 0.5 g l^–1 h^–1. No L(+)-lactic acid was found in the medium.     

Cloning and characterization of a β-galactosidase encoding region in Lactobacillus coryniformis CECT 5711

A chromosomal DNA fragment of 7.8 kb from Lactobacillus coryniformis CECT 5711 was cloned in Escherichia coli K-12 and was found to express a functional β-galactosidase. Nucleotide sequence analysis showed that this fragment contained two partially overlapping genes, the lacL (1,881 bp) and the lacM (960 bp), that encode the subunits of a heterodimeric β-galactosidase, with estimated molecular masses of 72,129 and 35,233 Da, respectively. Other three incomplete open reading frames showing homology to another β-galactosidase, an α-galactosidase, and a galactokinase, respectively, were also found. The L. coryniformis β-galactosidase was overproduced in E. coli by using an isopropyl-β-d-thiogalactopyranoside (IPTG) expression system. Two new proteins with an estimated M _r s of approximately 72,000 and 35,000 appeared upon induction with IPTG, and extracts of the recombinant E. coli strain showed β-galactosidase activity.     

黑茶微生物学研究进展

黑茶中存在着大量的生物活性物质,主要是黑茶加工过程中微生物作用所致。就黑茶加工过程中的主要微生物、微生物的酶促作用及其品质形成机理进行综述。     

Fermentation of brined turnip roots using Lactobacillus plantarum and Leuconostoc mesenteroides starter cultures

The controlled fermentation of turnip slices using Lactobacillus plantarum or Leuconostoc mesenteroides as starter cultures led to earlier acid production and earlier and more pronounced inhibition of Enterobacteriaceae than with uninoculated (natural) fermentation. Unlike the natural fermentation, the controlled fermentations did not show a yeast secondary fermentation and also had a better colour. Due to its ability to produce higher amounts of acid, the use of Lact. plantarum is more desirable than of Leuc. mesenteroides.     

Chemical modifications of the cell-surface components of Lactobacillus fermentum FTPT 1405 and their effect on the flocculation of Saccharomyces cerevisiae

The effect of treatment of Lactobacillus fermentum with several protein- and carbohydrate-modifying reagents on the bacterium's ability to flocculate Saccharomyces cerevisiae was investigated. The proteinaceous nature of the cell-surface components of L. fermentum which are responsible for floc formation was confirmed by inactivation of floc formation following photo-irradiation, with Methylene Blue or Rose Bengal as sensitizer, or acylation with acetic anhydride, maleic anhydride or acetylimidazole, and by the reaction of the components with nitrous acid, I₂ and performic acid.The phenolic hydroxyl group of tyrosine and the indole group of tryptophan appear essential for flocculation. Proteinaceous components of the yeast cell surface and carbohydrate components on the bacterial cell surface were not required for flocculation but carbohydrate residues on the yeast surface were essential.     

Genotypic analyses of lactobacilli with a range of tannase activities isolated from human feces and fermented foods

A total of 77 tannase producing lactobacilli strains isolated from human feces or fermented foods were examined for their genotypic profiles and intensities of tannase production. With a PCR-based assay targeting recA gene, all strains except one isolate were assigned to either Lactobacillus plantarum, L. paraplantarum, or L. pentosus whereas a 16/23S rDNA targeted PCR-based assay identified all except 6 isolates (inclusive of the above one isolate) as one of the closely related species. Subsequent DNA/DNA hybridization assays revealed that these 6 exceptional isolates showed low homology (between 1.2% and 55.8% relative DNA binding) against type strains of the three species. Supplemental carbohydrate fermentation profiles on the 6 isolates indicated that two of them were identified as L. acidophilus, one as Pediococcus acidilactici, one as P. pentosaceus, and two remained unidentifiable. The evidence suggests that the 16/23S rDNA targeted PCR assay can be used as a reliable identification tool for the closely related lactobacilli, and that the tannase gene is widely distributed within members of the Lactobacillaceae family. Meanwhile, a randomly amplified polymorphism DNA (RAPD) analysis revealed that all except 8 isolates were well allocated in 4 major RAPD clusters, though not species specific, consisting of two L. plantarum predominant clusters, one L. paraplantarum predominant, and one L. pentosus predominant. The RAPD patterns of the 8 non-clustered isolates, which consisted of the 6 unidentifiable isolates and 2 isolates identified as L. pentosus, were <40% similarity to those belonging to the 4 clusters. A quantitative assay of the tannase activities showed that there was a marked variation in the activities among the strains, which did not correlate with either species identification or clustering by RAPD.