酱香型酒醅产香芽孢杆菌的分离鉴定及其代谢产物分析

本文研究了酱香型酒醅中的产香芽孢杆菌及其优势代谢产物。通过平板分离法从酱香型酒醅中筛选出5株芽孢杆菌,采用PLFA技术对其鉴定,分别为:蜡样芽孢杆菌(Bacillus ereus)、泛酸枝芽孢杆菌(Virgibacillus pantothenticus)、巨大芽孢杆菌(Bacillus megaterium)、枯草芽孢杆菌(Bacillus subtilis)和地衣芽孢杆菌(Bacillus licheniformis);革兰氏染色试验结果说明:这五类菌株均为革兰氏阳性菌;生化分析发现:枯草芽孢杆菌产淀粉酶能力最强,巨大芽孢杆菌蛋白质水解能力最强;以高粱粉为底物进行固态发酵,采用GC-MS分析技术对发酵代谢产物进行分析表明:菌株的优势产物主要为3-羟基-2-丁酮,另外还有少量的2,3-丁二醇和酯类等芳香物质。蜡样芽孢杆菌、泛酸枝芽孢杆菌、巨大芽孢杆菌、枯草芽孢杆菌和地衣芽孢杆菌这五类菌株是酱香型白酒主要的产香功能菌。     

高温大曲中产吡嗪芽孢杆菌的分离鉴定及发酵产物分析

该试验从高温大曲中筛选产吡嗪芽孢杆菌（Bacillus）,通过形态观察及磷脂脂肪酸（PLFA）分析对其进行鉴定,并采用发酵试验分析其代谢产物。共筛选出3株芽孢杆菌,即菌株B1、B2、B3。经分析鉴定后得出：菌株B1为蜡样芽孢杆菌（Bacillus cereus）;菌株B2和B3为萎缩芽孢杆菌（Bacillus atrophaeus）。3株菌发酵产物分析结果表明,在液态发酵条件下3株菌发酵产吡嗪,其中菌株B2和B3发酵产物中吡嗪相对含量较高,均＞60%;固态发酵条件下生成吡嗪前体物质3-羟基-2-丁酮,且发酵产物中相对含量均＞75%。表明这3株芽孢杆菌对酱香型白酒风味物质的产生有着一定的影响。     

基于酶学特性筛选大曲来源芽孢杆菌用于强化酿酒

通过分析来源于清香型、浓香型和酱香型大曲的105 株芽孢杆菌的产淀粉酶和蛋白酶的能力,优选出1 株地衣芽孢杆菌（Bacillus licheniformis）B.L-1和1 株枯草芽孢杆菌（B. subtilis）B.S-1,将其分别应用于清香型白酒酿造中,探究强化接种微生物对发酵的影响。发酵结束后,在酒醅中共检测到挥发性代谢产物38 种,通过多元统计分析,在强化B.L-1组和B.S-1组中分别筛选出差异代谢物21 个和11 个（VIP＞1;P＜0.05）,其中4-乙基-2-甲氧基苯酚、辛酸乙酯、3-甲基丁酸乙酯和四甲基吡嗪在2 组强化中均为差异代谢物,含量显著升高。结果表明,用酶学特性进行菌株筛选能够快速有效地获得特定功能菌株,由此获得的菌株进行强化发酵可显著提高酒醅中挥发性风味物质含量。该方法可以有效地为大曲微生物合成群落重塑提供菌种资源。     

中高温大曲中芽孢杆菌多样性及代谢特征研究

为探究大曲中芽孢杆菌的代谢特征和功能性,首先采用传统培养法结合分子生物学技术从中高温大曲中分离、鉴定芽孢杆菌,对其微生物多样性进行分析;然后通过耐受性分析从中筛选优势菌,最后利用代谢组学方法分析其代谢特性。结果表明,共分离、鉴定得到49株芽孢杆菌,其中3株芽孢杆菌耐受性较好,分别为解淀粉芽孢杆菌（Bacillus amyloliquefaciens）BA-5、枯草芽孢杆菌（Bacillus subtilis）BS-7和贝莱斯芽孢杆菌（Bacillus velezensis）BV-10。从单菌株及混合菌株发酵后的发酵液中共检测到23种挥发性代谢物和52种非挥发性代谢物,其中,愈创木酚以菌株BS-7单独培养时含量最高,为8.56 mg/L。同时芽孢杆菌混合发酵会增加4-乙烯基愈创木酚的生成量,在菌株BV-10和BA-5混合培养后,达到104.47 mg/L,说明芽孢杆菌单菌株及种间协同作用对白酒酿造中的特征物质形成具有重要影响。     

酱香型大曲中一株产香芽孢杆菌的分离鉴定

以酱香型白酒高温大曲为材料,采用平板分离法初步筛选出11株芽孢杆菌;通过麸皮培养基在55℃条件下液态发酵,进一步筛选出1株产焦酱香的芽孢杆菌(MT6),并结合菌株生理生化和16S rRNA基因序列对该菌株进行鉴定。结果表明,MT6为解淀粉芽孢杆菌(Bacillus sp.)。该菌株可制成微生物强化菌剂,初步应用于高温型大曲酒的增香提质。     

芽孢杆菌LWM1的分离鉴定及其对蜡样芽孢杆菌的抑制作用

从土壤样品中分离出10株芽孢杆菌（Bacillus spp.）,以蜡样芽孢杆菌（Bacillus cereus）为指示菌株,采用牛津杯扩散法筛选出一株具有较强抑菌活性的菌株LWM1。综合形态学、生理生化试验、基质辅助激光解吸电离飞行时间质谱（MALDI-TOF MS）及16S rDNA基因序列同源性分析,菌株LWM1被初步鉴定为一株解淀粉芽孢杆菌（Bacillus amyloliquefaciens）,并研究了其在马铃薯葡萄糖水（PDW）和营养肉汤培养基（NB）中发酵上清液对蜡样芽孢杆菌的抑制效果。结果表明,PDW培养基更有利于菌株LWM1生长和抑菌物质产生。因此,可利用PDW培养基为主要底物大规模发酵制备菌株LWM1的抑菌物质。     

细菌型豆豉发酵芽孢杆菌的筛选与鉴定

对贵州省10 个细菌型豆豉产区的样品进行菌种分离与鉴定。旨在通过纯种发酵、口感评测、产蛋白酶能力测定、产气实验,筛选出能够取代自然发酵、蛋白酶产量高、发酵风味好、发酵不产气的芽孢杆菌菌株。结果从分离的184 株芽孢杆菌中,筛选出3 株发酵品质突出且不产气的菌株：BJ3-2、BJ1-3 和ZY4-5,其产蛋白酶能力(h/c)分别为3.60、1.71 和1.50。生理生化鉴定和16S rDNA 序列分析结果显示,它们均为枯草芽孢杆菌。扩大纯种发酵实验证明,可以将其作为工业发酵参考菌株。     

乳酸发酵短杆菌中碳架流向赖氨酸的导向与分析

对乳酸发酵短杆菌生物合成赖氨酸的代谢途径及其代谢流量从理论上进行了分析，计算了乳糖发酵短杆菌合成赖氨酸的最大理论转化率。对代谢途径及其遗传调控进行了分析，通过NTG诱变育成了一株带有FP^S、AEG^r、Ma^r和Leu^-4种遗传标记的赖氨酸高产菌株，使赖氨酸的产量提高到54.6g/L，并分析了这些标记对代谢流量改变的影响。     

大曲中产酱香芽孢杆菌的筛选及其代谢产香探析

对茅台酒生产各环节所采集的28个样品进行了初步分析,从高温大曲制作过程的不同环节筛选出芽孢杆菌104株,用麦曲模仿升温发酵筛选产香的菌株,经鉴定分别为枯草芽孢杆菌、解淀粉芽孢杆菌、地衣芽孢杆菌等,其中产酱香优良的菌株25株,分为多种香味,与不产香型的细菌对比,产酱香的25株均能产生二乙酰、乙偶姻、蛋白酶、淀粉酶等,结合茅台的生产流程分析了其产香的可能机制,得到结论：芽孢杆菌在大曲发酵过程中产生蛋白酶和淀粉酶等多种酶类和代谢物质,进而在高温、偏酸环境下通过美拉德反应产生吡嗪等多种茅台酒特征香味物质。     

一株贝莱斯芽孢杆菌的生长特性及抑菌活性研究

从自然发酵海洋鱼酱油中分离得到了一株具有多种蛋白酶活性与糖酶活性的贝莱斯芽孢杆菌SW5菌株,为探究贝莱斯芽孢杆菌SW5的抑菌特性,研究了SW5菌株的生长及生理生化特性,验证了SW5菌株发酵上清液对食品中多种常见病原菌的抑制能力;并利用液相色谱-质谱联用技术鉴定了其中的抑菌物质.结果表明:菌株SW5在35℃、pH值5时生...     

Interactions among lactic acid starter and probiotic bacteria used for fermented dairy products

Interactions among lactic acid starter and probiotic bacteria were investigated to establish adequate combinations of strains to manufacture probiotic dairy products. For this aim, a total of 48 strains of Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus, Lactococcus lactis, Lactobacillus acidophilus, Lactobacillus casei, and Bifidobacterium spp. (eight of each) were used. The detection of bacterial interactions was carried out using the well-diffusion agar assay, and the interactions found were further characterized by growth kinetics. A variety of interactions was demonstrated. Lb. delbrueckii subsp. bulgaricus was found to be able to inhibit S. thermophilus strains. Among probiotic cultures, Lb. acidophilus was the sole species that was inhibited by the others (Lb. casei and Bifidobacterium). In general, probiotic bacteria proved to be more inhibitory towards lactic acid bacteria than vice versa since the latter did not exert any effect on the growth of the former, with some exceptions. The study of interactions by growth kinetics allowed the setting of four different kinds of behaviors between species of lactic acid starter and probiotic bacteria (stimulation, delay, complete inhibition of growth, and no effects among them). The possible interactions among the strains selected to manufacture a probiotic fermented dairy product should be taken into account when choosing the best combination/s to optimize their performance in the process and their survival in the products during cold storage.     

Influence of cofermentation by amylolytic Lactobacillus strains and probiotic bacteria on the fermentation process,viscosity and microstructure of gruels made of rice,soy milk and passion fruit fiber

Gruels tailored to school-age children and made of soy milk and rice flour with or without total dietary fiber from passion fruit by-product were fermented by amylolytic lactic acid bacteria strains (Lactobacillus fermentum Ogi E1 and Lactobacillus plantarum A6), by commercial probiotic bacteria strains (Lactobacillus acidophilus L10, Lactobacillus casei L26 and Bifidobacterium animalis subsp. lactis B94) and by co-cultures made of one amylolytic and one probiotic strain. The influence of ingredient composition and bacterial cultures on kinetics of acidification, α-amylase activity of the bacteria, apparent viscosity and microstructure of the fermented products was investigated. During fermentation of the gruels, α-amylase activity was determined through the Ceralpha method and apparent viscosity, flux behavior and thixotropy were determined in a rotational viscometer. Rheological data were fitted to Power Law model. The combination of amylolytic and probiotic bacteria strains reduced the fermentation time of the gruels as well as increased the α-amylase activity. The addition of passion fruit fiber exerted less influence on the apparent viscosity of the fermented products than the composition of the bacterial cultures. Scanning electron microscopy provided evidence of exopolysaccharide production by amylolytic bacteria strains in the food matrices tested. The co-cultures made of amylolytic and probiotic bacteria strains are suitable to reduce the fermentation time of a soy milk/rice matrix and to obtain a final product with pH and viscosity similar to yoghurt.     

益生菌发酵蓝莓花色苷的代谢规律

选用嗜热链球菌、两岐双歧杆菌、植物乳杆菌进行纯种发酵含有蓝莓花色苷提取液的培养液,考察了益生菌发酵过程中活菌数、体外抗氧化性、有机酸、单体花色苷和酚酸等组分的变化情况。结果表明,发酵48 h后,三种益生菌的活菌数均增至8.0 lg CFU/mL左右,两岐双歧杆菌的活菌数最高(P<0.05),发酵后不同菌株发酵样的ABTS+·清除能力显著提升(P<0.05),其中两岐双歧杆菌发酵样品抗氧化能力最强(P<0.05);但植物乳杆菌发酵样品中乳酸含量最高(P<0.05);发酵过程中单体花色苷含量呈下降趋势,两岐双歧杆菌发酵样品花色苷组分与其它两株菌发酵的样品差异较大;绿原酸、对香豆酸和咖啡酸的含量总体呈现下降趋势,而没食子酸、丁香酸和阿魏酸含量呈上升趋势,主成分分析图中三株益生菌发酵样的分布差异较大。以上结果为进一步解释益生菌发酵代谢花色苷的机理提供了参考。     

Characterization of probiotic bacteria involved in fermented milk processing enriched with folic acid

Yogurt products fermented with probiotic bacteria are a consumer trend and a challenge for functional food development. So far, limited research has focused on the behavior of the various probiotic strains used in milk fermentation. In the present study, we characterized folic acid production and the sensory and textural characteristics of yogurt products fermented with probiotic bacteria. Yogurt fermented with Lactobacillus plantarum had improved nutrient content and sensory and textural characteristics, but the presence of L. plantarum significantly impaired the growth and survival of Lactobacillus delbrueckii ssp. bulgaricus during refrigerated storage. Overall, L. plantarum was a good candidate for probiotic yogurt fermentation; further studies are needed to understand the major metabolite path of lactic acid bacteria in complex fermentation.     

Incorporation of citrus fibers in fermented milk containing probiotic bacteria

The incorporation of Lactobacillus acidophilus CECT 903, Lactobacillus casei CECT 475 and Bifidobacterium bifidum CECT 870 together with lemon (LF) and orange (OF) fibers obtained from juice by-products were tested in (i) a model system: fiber enriched with de Man Rogosa Sharp (MRS) broth cultured with each probiotic bacteria and (ii) evaluation of populations of probiotic bacteria in fermented milks formulated with citrus fibers. Citrus fibers enhanced L. acidophilus CECT 903, and L. casei CECT 475 survival in MRS during refrigerated storage, whereas erratic results were obtained for B. bifidum CECT 870, OF enhanced its growth and LF had inhibitory effect. Populations of probiotic bacteria decreased with storage time in MRS broth. The presence of yogurt starter bacteria in probiotic fermented milks favored the growth and survival of L. acidophilus and B. bifidum. Citrus fiber presence in fermented milks also enhanced bacterial growth and survival of the tested probiotic bacteria. This study indicates that citrus fiber enriched fermented milk have good acceptability and are good vehicles for a variety of commercial probiotics but survival of B. bifidum will need to be improved.     

The influence of probiotic fermented milk product on colon microbiota, hematological parameters and cell immunity in rats

Influence of probiotic fermented milk product on the intestinal microbiota, hematological parameters and immune status of the experiment in vivo at Wistar rats was studied. It was shown, that entering of probiotic strains of Bifidobacterium bifidum 791, Bifidobacterium longum B-379M and Lactobacillus acidophilus NK1 u Streptococcus thermophilus in composition fermented milk products in the total quantity of 2,1 x 10(7) CFU/ sm3 in digestive tract within three weeks has a positive influence on the resident of colon microbiota. Significant increasing of population levels of Bifidobacterium, Enterobacteriaceae with normal biochemical properties, registered a strong tendency to increase the content of Lactobacteria, which led to a decreasing the number of potential pathogenic transient flora with pathogenic factors. Monitoring of body mass in experimental animals has shown that including of fermented milk product with probiotic strains in diet has a positive influence on the feed uptake. Probiotic properties of the product also have stimulated effect on the immune status of the rat: improvements in cell immunity (increasing the relative amount of T-helper cells, immuneregulatory index) and hematological parameters (increase     

EFFECT OF COLD STORAGE ON CULTURE VIABILITY AND SOME RHEOLOGICAL PROPERTIES OF FERMENTED MILK PREPARED WITH YOGURT AND PROBIOTIC BACTERIA

ABSTRACT

We examined the effect of storage time on culture viability and some rheological properties (yield stress, storage modulus, loss modulus, linear viscoelastic region, structural recuperation and firmness) of fermented milk made with Lactobacillus delbrueckii ssp. bulgaricus, Lactobacillus acidophilus (LA) and Bifidobacterium animalis ssp. lactis in coculture with Streptococcus thermophilus (ST). Acidification profiles and factors that affect viability (postfermentation acidification, acidity and dissolved oxygen) were also studied during 35 days at 4C. Fermented milk prepared with a coculture of ST and Bifidobacterium lactis gave the most constant rheological behavior and the best cell viability during cold storage; it was superior to ST plus LA for probiotic fermented milk production.

PRACTICAL APPLICATIONS

Probiotic cultures should grow quickly in milk, provide adequate sensory and rheological properties to the product, and remain viable during storage. Commercially, it is very common to use yogurt starter culture (i.e. Streptococcus thermophilus[ST] and Lactobacillus delbrueckii ssp. bulgaricus) in combination with the probiotic bacteria in order to reduce fermentation time. However, LB tends to post acidify fermented milk, which reduces the viability of the probiotic bacteria; thus, it is recommended to use starter cultures devoid of this species. We found that the technological properties and the viability of the probiotic bacterium Bifidobacterium animalis ssp. lactis BL O4 in coculture with ST make it suitable for probiotic fermented milk production; it produces rheological characteristics similar to those of yogurt.     

嗜酸乳杆菌和双歧杆菌益生特性的研究

以两株嗜酸乳杆菌和三株动物双歧杆菌为研究对象,详细研究它们的耐胃酸性、耐胆汁盐性、抑菌性和抗药性。结果表明:五株益生菌具有良好的耐酸耐胆汁盐性,双歧杆菌的耐酸性较强于嗜酸乳杆菌;抑菌性和抗药性结果表明:五株益生菌对致病菌大肠杆菌、金黄色葡萄球菌和沙门氏菌均有抑制作用,嗜酸乳杆菌的抑菌性较强于双歧杆菌;五株益生菌对三种抗生素乙酰螺旋霉素、链霉素和青霉素均敏感,敏感程度各异。     

Viability of probiotic (Bifidobacterium, Lactobacillus acidophilus and Lactobacillus casei) and nonprobiotic microflora in Argentinian Fresco cheese

We evaluated the suitability of Argentinian Fresco cheese as a food carrier of probiotic cultures. We used cultures of Bifidobacterium bifidum (two strains), Bifidobacterium longum (two strains), Bifidobacterium sp. (one strain), Lactobacillus acidophilus (two strains), and Lactobacillus casei (two strains) in different combinations, as probiotic adjuncts. Probiotic, lactic starter (Lactococcus lactis and Streptococcus thermophilus), and contaminant (coliforms, yeasts, and molds) organisms were counted at 0, 30, and 60 d of refrigerated storage. Furthermore, the acid resistance of probiotic and starter bacteria was determined from hydrochloric solutions (pH 2 and 3) of Fresco cheese. The results showed that nine different combinations of bifidobacteria and L. acidophilus had a satisfactory viability (count decreases in 60 d <1 log order) in the cheese. Both combinations of bifidobacteria and L. casei cultures assayed also showed a satisfactory survival (counts decreased <1 log order for bifidobacteria but no decrease was detected for L. casei). On the other hand, the three combinations of bifidobacteria, L. acidophilus, and L. casei tested adapted well to the Fresco cheese environment. When a cheese homogenate at pH 3 was used to partially simulate the acidic conditions in the stomach, the probiotic cultures had an excellent ability to remain viable up to 3 h. At pH 2, the cell viability was more affected; B. bifidum was the most resistant organism. This study showed that the Argentinian Fresco cheese could be used as an adequate carrier of probiotic bacteria.     

Evaluation of the effect of supplementing fermented milk with quinoa flour on probiotic activity

In this work, we investigated the effect of supplementing fermented milk with quinoa flour as an option to increase probiotic activity during fermented milk production and storage. Fermented milk products were produced with increasing concentrations of quinoa flour (0, 1, 2, or 3 g/100 g) and submitted to the following analyses at 1, 14, and 28 d of refrigerated storage: postacidification, bacterial viability, resistance of probiotics to simulated gastrointestinal (GI) conditions, and adhesion of probiotics to Caco-2 cells in vitro. The kinetics of acidification were measured during the fermentation process. The time to reach maximum acidification rate, time to reach pH 5.0, and time to reach pH 4.6 (end of fermentation) were similar for all treatments. Adding quinoa flour had no effect on fermentation time; however, it did contribute to postacidification of the fermented milk during storage. Quinoa flour did not affect counts of Bifidobacterium animalis ssp. lactis BB-12 or Lactobacillus acidophilus La-5 during storage, it did not protect the probiotic strains during simulated GI transit, and it did not have a positive effect on the adhesion of probiotic bacteria to Caco-2 cells in vitro. Additionally, the adhesion of strains to Caco-2 cells decreased during refrigerated storage of fermented milk. Although the addition of up to 3% quinoa flour had a neutral effect on probiotic activity, its incorporation to fermented milk can be recommended because it is an ingredient with high nutritive value, which may increase the appeal of the product to consumers.