Nisin expression production from Lactococcus lactis in milk whey medium

BACKGROUND: Nisin is a commercially available bacteriocin produced by Lactococcus lactis ATCC 11454 and used as a natural agent in the biopreservation of food. In the current investigation, milk whey, a byproduct from dairy industries was used as a fermentation substrate for the production of nisin. Lactococcus lactis ATCC 11454 was developed in a rotary shaker (30 °C/36 h/100 rpm) using two different media with milk whey (i) without filtration, pH 6.8, adjusted with NaOH 2 mol L^?1 and without pH adjustment, both autoclaved at 121 °C for 30 min, and (ii) filtrated (1.20 µm and 0.22 µm membrane filter). These cultures were transferred five times using 5 mL aliquots of broth culture for every new volume of the respective media. RESULTS: The results showed that culture media composed of milk whey without filtration supplied L. lactis its adaptation needs better than filtrated milk whey. Nisin titers, in milk whey without filtration (pH adjusted), was 11120.13 mg L^?1 in the second transfer, and up to 1628‐fold higher than the filtrated milk whey, 6.83 mg.L^?1 obtained in the first^t transfer. CONCLUSIONS: Biological processing of milk byproducts (milk whey) can be considered a profitable alternative, generating high‐value bioproducts and contributing to decreasing river disposals by dairy industries. Copyright © 2008 Society of Chemical Industry     

1 株水开菲尔粒中植物乳杆菌的鉴定及产细菌素基因分析

目的：对从水开菲尔粒中分离得到1 株能产生抑菌物质的菌株QF01进行菌种鉴定,并对其产细菌素进行实验、鉴定和基因序列分析。方法：通过牛津杯法测定抑菌能力,采用聚合酶链式反应（polymerase chain reaction,PCR）扩增16S rDNA和细菌素相关基因并测序,利用ProParam tool、TMHMM 2.0、InterProScan、SOPM和SWISS-MODEL在线软件对基因编码产物进行分析。结果：该菌株产的细菌素对大肠杆菌（Escherichia coli JM109）有明显的抑制作用,通过16S rDNA序列分析初步确定该菌株属于植物乳杆菌（Lactobacillus plantarum）。该菌株含有plnD、plnEF、plnV、plnR四种基因,其中plnV基因编码产物有跨膜螺旋结构,其结构存在信号肽特征。此外,从三级结构的模型预测得到4?种基因的编码产物均存在α-螺旋、β-转角、伸展链和无规则卷曲。结论：从水开菲尔粒分离得到的L. plantarum QF01菌株,含有plnD、plnEF、plnV、plnR细菌素基因,对大肠杆菌有很好的抑制作用。     

乳酸菌中抗李斯特细菌素的筛选及理化性质分析

从鱼肉丸中分离筛选到1株具有抑菌活性的乳酸菌菌株Y153,对单核细胞增生李斯特菌ATCC54003的生长具有良好的抑制作用。16SrRNA序列同源性分析鉴定乳酸菌Y153为乳酸链球菌属（Streptococcus）。在排除有机酸、过氧化氢的干扰后,确定该抑菌物质为蛋白类物质,即细菌素,命名为细菌素Y153。理化性质分析表明,细菌素Y153具有较好的热稳定性、酸碱稳定性可被人体内蛋白酶降解的特性。由此对乳酸链球菌所产细菌素Y153有了初步的研究,为开发天然的食品防腐剂奠定理论基础。     

植物乳杆菌KLDS1.0391在酸奶体系中的细菌素产生特点

植物乳杆菌KLDS1.0391能够合成细菌素,也是益生菌,在食品中既可作为益生菌使用,也可作为辅助发酵剂用于生物防控,该研究主要考察了KLDS1.0391菌株在酸奶体系中细菌素的产生特点。研究结果表明,在发酵的6 h期间,抑菌活性随发酵时间延长而增强,发酵结束时,添加植物乳杆菌KLDS1.0391酸奶组的抑菌活性显著高于仅使用酸奶发酵剂的对照组(P<0.01)。与对照组相比,加入辅助发酵剂的实验组的感官品质未发生明显的变化。植物乳杆菌KLDS1.0391具备开发益生酸奶的潜力。     

1株产细菌素植物乳杆菌的筛选及所产细菌素的理化性质分析

从浙江省生产的一种火腿制品中分离筛选到1株具有抑菌活性的乳酸菌菌株LH-09,对单核细胞增生李斯特菌ATCC54003的生长具有良好的抑制作用.16SrRNA序列同源性分析鉴定乳酸菌LH-09为植物乳杆菌.在排除有机酸、过氧化氢的干扰后,确定该抑菌物质为蛋白类物质,即细菌素.理化性质分析表明细菌素LH-09具有较好的热稳定性、酸碱稳定性,可被人体内蛋白酶降解.N-羟甲基甲基甘氨酸-SDS-PAGE电泳确定细菌素LH-09的分子质量在2～6 kDa之间.     

乳酸菌产细菌素生物学特性的研究及培养条件的优化

目的研究乳酸菌产细菌素的生物学特性并优化培养条件。方法将实验室保藏的EF2(植物乳杆菌)和PP2(嗜酸乳杆菌)2株乳酸菌进行混合发酵,采用牛津杯法分析细菌素的生物学特性,并通过单因素实验和正交实验优化了EF2和PP2混合发酵产细菌素的培养条件。结果细菌素在酸性、中性、弱碱性条件下活性较强;耐高温,属于热稳定性物质,它对胰蛋白酶、胃蛋白酶、蛋白酶K和中性蛋白酶敏感,对α-淀粉酶和木瓜蛋白酶不敏感,是广谱细菌素。EF2、PP2混合发酵产细菌素的最佳培养基成分为葡萄糖20g/L、蛋白胨12.5 g/L、牛肉膏15 g/L、酵母膏5 g/L、K2HPO4·3H2O 2 g/L、无水乙酸钠5 g/L、柠檬酸三铵2 g/L、MgSO40.2 g/L、MnSO4 0.05 g/L、Tween-80 2 mL/L、蒸馏水1 L。最佳培养条件为:初始pH为6.5、接种量4%,装液量100 mL/250 mL,发酵温度35℃,在此条件下,细菌素抑菌活性比优化前提高了1.36倍。结论乳酸菌EF2和PP2混合培养得到的细菌素为具有较好抗性的广谱细菌素,并通过单因素实验和正交实验确定了2株乳酸菌混合培养产细菌素的优化条件。     

乳酸菌素的研究现状和发展趋势

乳酸菌素是由乳酸菌产生的一种具有活性的多肽或蛋白质物质，大部分细菌素对近缘关系的细菌有抑制作用，少数细菌素抑菌谱很广。主要可分为热稳定的小分子肽，热敏感的大分子蛋白和羊毛硫抗生素。乳酸菌素是一种纯乳酸菌产生的制剂，是将脱脂乳经杀菌、真空浓缩．再经乳酸菌发酵后干燥而制成的乳酸菌体及其代谢产物混价粉状物，可作医药用或食品添加剂，属疗效型乳制品。本文对乳酸菌素的分类、抑菌机理及在食品和医药方面的应用作了全面系统的综述，并指出了今后的研究方向和应用前景。     

(S)-Reutericyclin: Susceptibility Testing and In Vivo Effect on Murine Fecal Microbiome and Volatile Organic Compounds

We aimed to assess the in vitro antimicrobial activity and the in vivo effect on the murine fecal microbiome and volatile organic compound (VOC) profile of (S)-reutericyclin. The antimicrobial activity of (S)-reutericyclin was tested against Clostridium difficile, Listeria monocytogenes, Escherichia coli, Enterococcus faecium, Staphylococcus aureus, Staphylococcus (S.) epidermidis, Streptococcus agalactiae, Pseudomonas aeruginosa and Propionibacterium acnes. Reutericyclin or water were gavage fed to male BALBc mice for 7 weeks. Thereafter stool samples underwent 16S based microbiome analysis and VOC analysis by gas chromatography mass spectrometry (GC-MS). (S)-reutericyclin inhibited growth of S. epidermidis only. Oral (S)-reutericyclin treatment caused a trend towards reduced alpha diversity. Beta diversity was significantly influenced by reutericyclin. Linear discriminant analysis Effect Size (LEfSe) analysis showed an increase of Streptococcus and Muribaculum as well as a decrease of butyrate producing Ruminoclostridium, Roseburia and Eubacterium in the reutericyclin group. VOC analysis revealed significant increases of pentane and heptane and decreases of 2,3-butanedione and 2-heptanone in reutericyclin animals. The antimicrobial activity of (S)-reutericyclin differs from reports of (R)-reutericyclin with inhibitory effects on a multitude of Gram-positive bacteria reported in the literature. In vivo (S)-reutericyclin treatment led to a microbiome shift towards dysbiosis and distinct alterations of the fecal VOC profile.     

抗食源性病原菌细菌素的筛选及特性研究

目的 筛选一种抗食源性病原菌的细菌素,并对其稳定性进行研究.方法 以食源性病原菌Bacillus cereus ATCC 14579、Listeria monocytogenes LM201、Listeria monocytogenes LM605为指示菌,采用琼脂扩散法筛选细菌素产生菌,通过离子交换树脂法和高效液相色...