Characterization and adsorption of a Lactobacillus plantarum virulent phage

Bacteriophage infection of lactic acid bacteria is considered one of the biggest worldwide problems in the food industry. Bacteriophages may cause negative effects on the fermentation of various dairy-based products. A virulent bacteriophage was isolated from an abnormal fermentation liquid of Lactobacillus plantarum IMAU10120. The characterization and influence of temperature, pH, divalent cations, and chloramphenicol on the adsorption ability of this phage were evaluated. The results showed that this phage belonged to the Siphoviridae family. It exhibited a burst time of 135 min and a burst size of approximately 215 counts expressed per milliliter per infective center. No significant effect was shown to influence its viability and adsorption at 10 to 37°C. More than 90% of phages exhibited infectivity from pH 5 to 9. Divalent ions and chloramphenicol did not have a significant influence on the adsorption of this phage. The information obtained in this study will enrich the database of lactobacilli virulent phages and provide a basis of information for the control of phages in the food fermentation industry.     

短乳杆菌的研究和应用进展

短乳杆菌是乳酸菌中乳杆菌属的重要菌种。研究和报道表明,短乳杆菌具有高产酸能力和解毒、抑菌、提高机体免疫能力等多种功能特性,已被逐渐应用于食品和医药生产中。     

一株曲拉源短乳杆菌的分离及其体外抑菌特性分析

摘要：目的 天然牦牛乳曲拉中蕴含着大量的乳酸菌，为丰富食品发酵的有益菌种资源，本试验分离筛选具有抑菌活性的乳酸菌。方法 以西藏牦牛乳曲拉为分离基质，MRS(De Man Rogosa Sharpe)加上1%CaCO3为选择鉴别培养基，运用形态学观察、生理生化试验、16S r RNA基因序列、药敏试验对分离菌株进行菌种鉴定，通过抑菌试验探究其抑菌活性。结果 分离菌株NWMCC0322被鉴定为短乳杆菌，其对青霉素类、四环素类、大环内酯类、酰胺醇类、喹诺酮类、磺胺类、头孢类药物敏感，对多烯类药物中敏。NWMCC0322对指示菌金黄色葡萄球菌的抑菌效果最好，其抑菌圈直径达12.0±0.6 mm，其次为甲型副伤寒沙门氏菌11.3±0.3 mm，大肠杆菌11.0±0.5 mm。结论 该短乳杆菌对食品污染常见菌株具有抑菌效果，在食品发酵中有较好的应用价值。     

Detection of Beer‐spoilage Lactobacillus brevis strains by Reduction of Resazurin

Lactobacillus brevis is the most common beer‐spoilage bacteria found in breweries. Due to its high prevalence and biodiversity, it is necessary to differentiate between the strains based on their hop tolerance. Forcing tests are often conducted for different types of beer, which can vary in cereal base, fermentation type, ethanol‐ and hop content. These conventional tests are considered to be the safest way to determine the ability of a given strain to cause beer‐spoilage, but they are very time consuming and costly. Since NADH₂ is used as cofactor by many cellular dehydrogenases, this study used the reduced form of intracellular nicotinamide adenine dinucleotide (NADH₂) as an indicator for microbial metabolic activity and thus ability to spoil beer, in order to reduce the time required to conduct the forcing tests for beer production. Beer‐spoiling L. brevis strains were detected among other strains in beer samples within two days (of sampling).     

啤酒腐败菌耐乙酸乳杆菌种特异性检测体系的建立与应用

以耐乙酸乳杆菌的3个特异性基因为靶标,设计并优化了3对耐乙酸乳杆菌的特异性引物,建立了基于SYBR GREEN实时荧光定量PCR的耐乙酸乳杆菌定性定量检测的标准检测(standard operation procedure,SOP)方法。利用耐乙酸乳杆菌CN247的基因组DNA作为标准品绘制了标准曲线,实现了对耐乙酸乳杆菌的定量检测,耐乙酸乳杆菌的最低检测限可达100 CFU/m L,精度可达10 CFU/m L。大生产样品在培养基中富集培养48 h后即可满足检测的要求,检出率为100%,整个检测时间控制在3 d以内,满足了啤酒企业对出厂产品快速检测的质量控制要求。     

副溶血性弧菌噬菌体的分离及其在即食虾中的应用

为了研究噬菌体作为天然生物防控剂应用于食品中的前景,本实验从水产品市场的污水中采用双层平板法分离纯化出一株烈性副溶血性弧菌噬菌体SHOU24,测定其生理特性,并探讨其在即食虾中的抑菌效果。结果表明:该噬菌体只对含有毒力基因tdh的副溶血性弧菌有裂解能力。电镜观察其形态表明该噬菌体属于长尾噬菌体科。SHOU24的最适p H为7~8。在50℃温度以下,存活率很高。抑菌实验结果表明该噬菌体在常温条件下对即食虾中副溶血性弧菌的生长具有良好的抑制作用,能使副溶血性弧菌的菌浓度下降1log CFU/g。本研究为副溶血性弧菌噬菌体SHOU24作为抑菌剂应用于食品中提供了一定的理论基础。      

Construction of a novel beer proteome map and its use in beer quality control

Beer proteins were analysed by two-dimensional gel electrophoresis (2DE). The protein species associated with major spots on 2DE gels were identified by mass spectrometry followed by a database search to construct a comprehensive beer proteome map. As a result, 85 out of 199 protein spots examined were positively identified and categorised into 12 protein species. A total of 11 beer samples were brewed from the malt of eight cultivars having different levels of protein modification. This experiment was designed to demonstrate the influences of barley cultivar and malt modification on beer protein composition and beer quality characters. The beers produced from these brewing trails were subsequently analysed by 2DE and their proteomes were compared. Cultivars and malt modification affected the concentration of several proteins in beer. Beer protein concentration was associated with differences in the desirable beer quality trait, foam stability. In addition, expression of yeast derived proteins were observed that may also influence beer quality. Overall, the application of a comprehensive beer proteome map provides a strong platform for detection and potential manipulation of beer quality related proteins.     

一株植物乳杆菌的分离鉴定及应用

从湖南自然发酵的酸豇豆中分离出一株疑似乳酸菌菌株L4,提取其16S rDNA,并经测序、同源性分析和系统发育树构建等,对其属种进行鉴定。结果表明,菌株L4为植物乳杆菌（Lactobacillus plantarum）。通过耐盐、耐酸和降解亚硝酸盐实验发现,菌株L4可在10%食盐含量条件下生长,耐受pH 2.5,对亚硝酸盐的降解率高达99%。接种菌株L4发酵萝卜干,以自然发酵萝卜干为对照,对发酵萝卜干进行感官评定初步探究该菌株发酵萝卜干的特性。结果表明,菌株L4可以缩短萝卜干发酵周期,提高发酵萝卜干感官评分。     

湘味卤豆干中腐败微生物的分离鉴定及控制

目的：更好地控制湘味卤豆干腐败微生物的生长,保证湘味卤豆干的食品安全。方法：采用平板划线法进行初筛,结合菌落形态观察、革兰氏染色、16S rDNA和ITS序列鉴定湘味卤豆干中的腐败微生物。结果：共分离筛选得到9株菌株,KZ2780-3和KZ2780-4为枯草芽孢杆菌（Bacillus subtilis）、NZ2559-1为蜡样芽孢杆菌（Bacillus cereus）、JZ2559-5为解淀粉芽孢杆菌（Bacillus amyloliquefaciens）、FZ2559-2为肺炎克雷伯氏菌（Klebsiella pneumoniae）、SZ2641-5为屎肠球菌（Enterococcus faecium）、RZ2641-7为溶血性葡萄球菌（Staphylococcus haemolyticus）、BZ2780-1为鲍氏不动杆菌（Acinetobacter baui）、CZ2780-5为橘青霉（Penicillium citri）。结论：引起湘味卤豆干腐败的菌株是枯草芽孢杆菌、蜡样芽孢杆菌、解淀粉芽孢杆菌、肺炎克雷伯氏菌、屎肠球菌、溶血性葡萄球菌、鲍氏不动杆菌、橘青霉。湘味卤豆干的控制方法是超高温瞬时杀菌技术、等离子体杀菌技术、天然抑菌物质结合生物防腐剂、真空包装、气调保鲜等。     

超氧化物歧化酶在啤酒生产过程中的研究及应用

超氧化物歧化酶普遍存在于生物体内,具有清除氧活性自由基的生物活性,在啤酒生产过程中具有重要的作用.本文对啤酒风味老化因素给予了分析,并对减少啤酒风味的老化提供了一定的技术方案,重点对影响老化的关键因素氧进行了论述,并给与清除和阻断氧的方法,超氧化物歧化酶作为一种抗氧化剂,本文分别对麦芽、酵母中的超氧化物歧化酶的特性进行了分析,并且对啤酒发酵中不同时期提高超氧化物歧化酶的含量的措施给予了探讨,在生产过程中添加外源性超氧化物歧化酶对于提高原麦汁的还原力,发酵液的抗氧化力以及成品啤酒的风味稳定性都有明显的作用,同时,本文就目前外源性超氧化物歧化酶的来源,存在的问题进行了探讨,并对其在工业化生产上的应用前景进行了分析和探讨.     

The impact of different hop compounds on the growth of selected beer spoilage bacteria in beer

Beer spoiling lactic acid bacteria are a major reason for quality complaints in breweries around the world. Spoilage by a variety of these bacteria can result in haze, sediment, slime, off-flavours and acidity. As these bacteria occur frequently in the brewing environment, using certain hop products that inhibit the growth of these spoilers could be a solution to prevent problems. To investigate the impact of seven different hop compounds (α-acids, iso-α-acids, tetrahydro-iso-α-acids, rho-iso-α-acids, xanthohumol, iso-xanthohumol and humulinones) on the growth of six major beer spoilage bacteria (Lactobacillus brevis. L. backi, L. coryniformis, L. lindneri, L. buchneri, Pediococcus damnosous), two concentrations (10 and 25 mg/L) of each hop substance were added to unhopped beer. The potential growth of the spoilage bacteria was investigated over 56 consecutive days. A comparison of the results shows a strong inhibition of growth of all spoilage bacteria at 25 mg/L of tetrahydro-iso-α-acids closely followed by α-acids as the second most inhibitory substance. The results showed a high resistance of L. brevis to all hop compounds as well as an inhibition of L. coryniformis and L. buchneri at low concentrations of most hop components. In comparison with the control sample, L. lindneri showed increased growth in the presence of some hop compounds (rho-iso-α-acids, xanthohumol, iso-xanthohumol, humulinones). © 2020 The Authors. Journal of the Institute of Brewing published by John Wiley & Sons Ltd on behalf of The Institute of Brewing & Distilling     

短乳杆菌天然质粒分类

为建立短乳杆菌天然质粒分类方法,通过质粒复制起始蛋白（replication initiation protein,Rep）进化树和基因组共线性分析,将短乳杆菌51 个天然质粒可以准确、有效地划分为6?个家族类型和11?个亚家族类型,并在家族4质粒中发现了一种新的复制子类型。研究结果表明,质粒Rep进化树和基因组共线性分析都是短乳杆菌天然质粒有效的分类方法,分类结果为今后短乳杆菌天然质粒科学分类和理性应用提供了理论研究依据。     

荧光微菌落技术快速检测啤酒有害菌的初步研究

建立了一种快速检测啤酒厌氧菌的方法,具体包括利用聚碳酸酯膜过滤啤酒样,厌氧培养36 h后对其上生长的微菌落采用二醋酸羧基荧光素(CFDA)避光染色10min,采用荧光显微镜对微菌落进行计数,同时对该法进行重复性试验并和常规平板培养计数法相比对,二者的菌落数均无显著性差异(p>0.05),微菌落法的最低检测限为4 cfu/mL.荧光微菌落法检测啤酒有害菌具有快速、经济、准确,易于操作的特点.     

Lactobacillus alimentarius: a specific spoilage organism in marinated herring

Spoilage characterised by bulging of lids and gas formation affected various product lots of different marinated herring types. Microbiological analyses resulted in growth on MRS and Rogosa SL agar. Altogether, 206 randomly selected colonies from two unspoiled and ten spoiled samples were characterised using phenotypical key tests and a 16 + 23S rRNA gene-based RFLP identification database. L. alimentarius was found to be the specific spoilage organism in all samples. All isolates obtained from the different product types were of the same clonal type. The slight rise in pH value together with marked gas production suggested a rare lactic acid bacteria spoilage type called 'protein swell'. L. alimentarius has not been previously associated with herring spoilage.     

豆腐酸浆中干酪乳杆菌的分离、鉴定及作为豆腐凝固剂的应用

通过平板涂布法和高效液相色谱法,以p H和产乳酸量为指标,从自然发酵酸浆中分离筛选出一株乳酸菌YQ336,对其进行菌株形态观察、菌落形态观察、生理生化鉴定以及16S rDNA序列分析,结果表明,该乳酸菌属于乳杆菌属的干酪乳杆菌。将分离出的干酪乳杆菌YQ336接种于豆腐黄浆水中纯种发酵制成豆腐凝固剂点制豆腐,与自然发酵酸浆点制的豆腐进行比较,发现两者的感官评分差异不显著(p>0.05),说明干酪乳杆菌YQ336可以作为新型豆腐凝固剂开发并使用。      

戊糖乳杆菌及其在食品工业中的应用

戊糖乳杆菌是一种重要的乳酸菌,广泛存在于传统发酵食品中,其在食品工业中的应用潜力受到越来越多的关注。本文综述了戊糖乳杆菌的生理生化性质、生物学功能及其在功能食品开发、橄榄发酵食品和生物表面活性剂方面的研究进展,为加快戊糖乳杆菌在食品工业中的应用提供理论参考。     

Probiotic and milk technological properties of Lactobacillus brevis

Two Lactobacillus brevis strains ATCC 8287 and ATCC 14869(T), were evaluated for their applicability as putative probiotics in dairy products. The strains expressed good in vitro adherence to human Caco-2 and Intestine 407 cells and tolerated well low pH, bile acids and pancreatic fluid under in vitro conditions. In antimicrobial activity assays, strain ATCC 8287 showed inhibitory properties toward selected potential harmful microorganisms, particularly against Bacillus cereus. Both L. brevis strains were resistant to vancomycin, which is typical for the genus Lactobacillus. The L. brevis strains were not able to acidify milk to yoghurt but were suitable as supplement strains in yoghurts. This was shown by producing a set of yoghurt products and analysing their rheological and sensory properties during a cold storage period of 28 days. Survival of the strains through human intestine was examined in 1-week feeding trials. Despite its human origin, L. brevis ATCC 14869(T) could not survive through the gastrointestinal (GI) tract, whereas L. brevis ATCC 8287 was detected in the faecal samples taken during and immediately after ingestion of the strain. In conclusion, L. brevis ATCC 8287 is a promising candidate as a probiotic supplement in dairy products.     

保加利亚乳杆菌的特性及其应用

保加利亚乳杆菌是乳酸菌中应用较广的一种,与人类的生活关系密切.文中介绍了保加利亚乳杆菌的生长特性、产酸特性、产香特性、产胞外多糖特性以及其在食品发酵、工业乳酸发酵、医疗保健和饲料行业等领域的应用.     

挤压膨化技术在啤酒工业中的应用研究进展

介绍了挤压膨化技术的特点、机理及该技术在啤酒工业中的应用,为该技术在啤酒工业中的进一步应用提供了依据。