保加利亚乳杆菌冻干保护剂的研究

采用正交试验研究了保加利亚乳杆菌在冷冻干燥条件下的最佳保护剂的筛选。结果表明：在所选的冷冻干燥保护剂中,VC影响极显著,脱脂乳和谷氨酸钠影响显著,明胶影响不显著;筛选出最佳复合保护刑组成为脱脂乳10％、VC0．5％、谷氨酸钠0．5％、明胶1．5％。     

Carbonyl Compounds Produced by the Growth of Lactobacillus bulgaricus

The carbonyl compounds produced by the growth of Lactobacillus bulgaricus on whey permeate supplemented with amino acids and on a defined medium were identified by reacting the media with 2,4-dinitrophenylhydrazine and separating the 2,4-dinitrophenylhydrazones by thin-layer chromatography. The 2,4-dinitrophenylhydrazones of ketoacids were reduced to the corresponding amino acids and identified by thin-layer chromatography. Compounds identified were ketoacids corresponding to alanine, valine, isoleucine, threonine, and histidine;acetaldehyde, propionaldehyde, butyraldehyde, valeraldehyde, benzaldehyde, phenylacetaldehyde, glyoxal, methylglyoxal, dihydroxyacetone, diacetyl, levulinic acid, and acetonylacetone.     

保加利亚乳杆菌冷冻干燥保护剂的筛选

采用响应面分析法筛选并优化了保加利亚乳杆菌冻干保护剂,研究发现在众多物质中脱脂乳、海藻糖、菊粉、麦芽糊精对菌种保护作用突出,以冻干后细胞存活率为响应值,当脱脂乳5.94%,海藻糖7.75%,菊粉8.39%,麦芽糊精9.04%作为混合保护剂使用时,细胞存活率达到90.46%。使用液氮进行预处理并且保护剂的体积为菌体两倍时可以使菌体存活率达到91.93%.     

保加利亚乳杆菌发酵黄瓜汁产物分析及生物活性评价

以黄瓜与鲜牛奶为原料,利用保加利亚乳杆菌（Lactobacillus bulgaricus）对黄瓜牛奶复合物进行发酵。并对发酵液的pH值、总酸、总糖、总酚、乳酸含量和抗氧化性进行分析。同时利用气相色谱-质谱对发酵液的挥发性成分进行分析。采用的发酵工艺为黄瓜汁∶纯牛奶=7∶3（V/V）,保加利亚乳杆菌接种量0.01%,初始pH值6.1,发酵温度37 ℃,发酵时间3 d。在此工艺下对提取的样品进行分析,测得发酵乳的总酸含量为50.5 g/L,总酚含量为0.165 mg/mL,其羟自由基清除率达87%,DPPH自由基清除率达85.12%。总抗氧化能力最高与0.85 mmol/L的Trolox的抗氧化能力相同。发酵液的挥发性成分中,烷类化合物（68.40%）和酯类化合物（10.61%）含量较高,酸类化合物（5.03%）和酮类化合物（0.98%）含量较低。     

Impedimetric method for estimating the residual activity of freeze-dried Lactobacillus delbrueckii ssp. bulgaricus

The residual activity of Lactobacillus delbrueckii ssp. bulgaricus cultures was analysed using pH and various impedimetric methods (impedance detection time (IDT), conductance and capacitance) to quantify the loss in activity following freeze-drying. The large variation recorded in IDT values for similar levels of activity suggests that IDT is not an adequate parameter for estimating the culture's fermentative activity. Comparison of the impedance signals generated revealed that capacitance yields values that are more reproducible than those of conductance, and also gives a better correlation with pH. Statistical analysis (p<0.05) indicated that there are no significant differences between the capacitance and the pH method when attempting to estimate residual activity.     

Critical water activity and amorphous state for optimal preservation of lyophilised lactic acid bacteria

The aim of this study was to investigate the influence of the water activity on the stability of lyophilised lactic acid bacteria, especially in the solid glassy region. Lactobacillus bulgaricus CFL1 was co-lyophilised with sucrose and stored under controlled relative humidity at 25 °C. Glass transition temperature (T_g), water activity, water content and loss of specific acidification activity during storage were determined. The rates of bacteria degradation were analysed as a function of water activity and as a function of the temperature difference between storage temperature and T_g. Above T_g, the degradation rate appeared related to the physical changes of the amorphous matrix. Below T_g, the optimal stability of the lyophilised bacteria was observed in the intermediate water activity range 0.1–0.214. An integrated analysis of the relationships between water activity, T_g, water content and biological activity appeared as a promising approach for optimising the freeze-drying process and predicting the storage stability.     

Retention of β-galactosidase activity in crude cellular extracts from Lactobacillus delbrueckii ssp. bulgaricus 11842 upon drying

Crude cellular extracts (CCEs) containing active β-galactosidase from Lactobacillus delbrueckii ssp. bulgaricus 11842 were spray-dried at three different outlet air temperatures (45, 55 or 65°C) or freeze-dried, with or without whey proteins, casein, whey or skim milk as drying adjuncts. The use of whey or skim milk resulted in significantly ( P   <  0.05) higher β-galactosidase activity retention in comparison to all other CCEs. This effect was not related to the initial total solids (TS) content (4–10%) of the feedstock solutions, but was presumably caused by the presence of lactose in the whey or skim milk CCE preparations.     

提高保加利亚乳杆菌抗冷冻性的研究

保加利亚乳杆菌(Lactobacillus bulgaricus)L.b-DR经脱脂乳培养基和MRS培养基活化、菊芋汁复合培养基培养、离心收获菌体,以12%脱脂乳作为冷冻保护剂,进行了冷冻试验。研究了在培养基中添加活性成分、培养基的起始pH值、培养温度、细胞收获的菌龄、保护剂的pH值对细胞冷冻存活率的影响。结果表明:在菊芋汁复合培养基中添加0.1%甘油或0.5%VE、培养基的起始pH值为6.0、37℃培养、对数末期或稳定初期收获菌体、保护剂pH值调至6.0,可显著提高保加利亚乳杆菌L.b-DR的冷冻存活率(P<0.05)。     

抗后酸化保加利亚乳杆菌的紫外诱变选育

利用紫外线对保加利亚乳杆菌ZLB进行诱变处理60s(菌株致死率大约为99%),中间培养后用青霉素筛选。处理液涂布培养后,选取生长缓慢或不长的40株接种于RSM(ReconstitutedSkimmedMilk)培养基中,随后选取凝固的12株做12℃时贮藏,最终得到产酸较慢的突变株ZU05。在42℃时,ZU05在RSM培养基中产酸量与ZLB一样。但是发酵脱脂乳在12℃贮藏时,ZU05产酸量与ZLB的产酸量有显著性的差异(p<0.01),其发生后酸化时间推迟了4d。同时,ZU05对链霉素的敏感性不同于ZLB且能稳定遗传。     

乳酸菌发酵大豆多肽工艺条件研究

以大豆分离蛋白为原料,经乳酸菌的发酵作用生产大豆多肽,并以大豆多肽含量为评判指标,通过正交试验得到发酵的最佳工艺条件:在接种量5%,发酵液初始pH7.0,发酵培养温度40℃,培养基中大豆分离蛋白浓度3%,摇瓶转速100r/min的条件下,经过30h的发酵,发酵液中多肽含量达3.98 mg/mL.     

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.     

保加利亚乳杆菌冻干菌种的研究

对酸奶发酵菌种之一--保加利亚乳杆菌的增菌培养基进行了筛选,得到了高活菌数的保加利亚乳杆菌增菌培养基,并进行冷冻升华干燥得到保加利亚乳杆菌的冻干菌种。结果表明:在添加有10%麦芽汁、10%番茄汁、0.05%CaCO3、1.0%乳糖的MRS基础培养基中培养保加利亚乳杆菌18h后活菌数可达到3.96×1011cfu/g。其冻干菌种的活菌数为2.53×1011cfu/g。     

Stimulation by Formate of Antimicrobial Activity of Lactobacillus bulgaricus in Milk

When sodium formate was added to skim milk at concentrations of 0.15 mM prior to fermentation by Lactobacillus bulgaricus, the antimicrobial activity of the milk fermented for 5 hr increased by 66% over control samples. Maximum stimulation was attained at 0.45 mM concentration and further increase was less stimulatory. The stimulatory effect of formate was neutralized in the samples incubated for 24 hr. Formate addition did not affect the pH of the fermented milk.     

Evidence for temperate bacteriophages in two strains of Lactobacillus bulgaricus

Lactobacillus bulgaricus strains LT1 and LT4 previously isolated from a yogurt factory were shown to be lysogenic and inducible by mitomycin C or u.v. irradiation, induction being optimal at the beginning of exponential growth. Five indicator strains (four of L. lactis, one of L. bulgaricus) were found in which the two phage lysates propagated well in a liquid medium, but formed plaques on bacterial lawns less readily. Ca2+ was required for the phage infection of the indicator strains to reach termination. Phage particles from each strain exhibited a comparable ultrastructural morphology under the electron microscope, having an isometric head, a triple collar and a noncontractile fibre-containing tail.     

保加利亚乳杆菌浓缩培养的研究

对培养保加利亚乳杆菌的基础培养基进行筛选,确定为MRS培养基。然后优化培养条件:发酵时间为12h,起始pH值为5.80,发酵温度为40℃。最佳培养基:MRS培养基 7.5%番茄汁 12%麦芽汁 0.009mol/LCaCl2 2%乳清。通过中和试验,保加利亚乳杆菌菌体浓度可达到9.55×109mL-1。     

[1]保加利亚乳杆菌发酵转化人参皂苷工艺研究

摘 要: 目的 以人参为原料, 通过保加利亚乳杆菌发酵提高人参皂苷含量。方法 利用单因素试验和响应面法优化发酵工艺, 并对发酵过程中原型人参皂苷生物转化可能途径进行分析。结果 在发酵培养基为MRS液体培养基的前提下, 最适发酵条件为发酵温度40℃, 发酵时间3 d, 接种量3%, 转化稀有人参皂苷含量在150 μg/mL。经对比发现, 原参中检测出Re、Rg1、Rb1、Rc、Rb2、Rd、Rh1 7种皂苷, 经过发酵后的人参中检测出Re、Rg1、Rb1、Rc、Rb2、Rh1、Rd、R-rg3、CK 9种皂苷。同时原参中的常规皂苷含量经发酵后有所下降, 稀有皂苷含量有所增加, 且多酚、黄酮含量增加, 总糖含量减少, 发酵过程中人参皂苷生物转化的可能途径与人参皂苷含量变化趋势一致。结论 保加利亚乳杆菌发酵人参能够有效将原型皂苷转化成稀有人参皂苷, 为人参的深加工奠定基础, 为人参发酵产品的开发和利用提供参考。     

响应面法优化保加利亚乳杆菌微胶囊制备工艺

为增强保加利亚乳杆菌（Lactobacillus bulgaricus）的抗逆性,提高其在产品中的存活率,该研究采用内源乳化法制备保加利亚 乳杆菌微胶囊,并通过单因素试验和响应面试验对其制备工艺进行优化。结果表明,最佳微胶囊制备工艺参数为海藻酸钠质量分数2%, 复合壁材海藻酸钠与果胶质量比1∶1,水相油相体积比1∶2.5,交联剂碳酸钙与海藻酸钠质量比1:2,乳化剂Span-80体积分数1.5%,搅拌 速率400 r/min。在此优化条件下,利亚乳杆菌微胶囊包埋率达到91.8%。     

抗后酸化保加利亚乳杆菌的亚硝基胍诱变选育

利用0.9mg/mL亚硝基胍对保加利亚乳杆菌ZLB进行诱变处理30min(菌株致死率为99%),中间培养后用青霉素筛选。处理液涂布培养后,选取生长缓慢或不长的32株接种于RSM(ReconstitutedSkimmedMilk)培养基中,随后选取凝固的16株做12℃贮藏,最终得到产酸较慢的突变株ZT224、ZT227。突变株与ZLB相比,在42℃时,ZT224、ZT227在RSM培养基中滴定酸度值明显减少。发酵脱脂乳在12℃贮藏时,ZT224的发酵乳在贮藏的20d内一直没有发生后酸化;ZT227发生后酸化的时间推迟了4d。同时,突变株ZT224、ZT227对链霉素的敏感性不同于出发菌株ZLB且能稳定遗传。      

保加利亚乳杆菌富集锌的条件研究

研究了保加利亚乳杆菌将无机态微量元素锌富集转化为细胞内的有机态微量元素锌的条件。正交实验结果表明,培养基中ZnSO4浓度为主要影响因素,培养温度、培养时间和接种量为次要影响因素,其中又以培养温度的影响较主要。最佳富集条件为,ZnSO4浓度400μg/mL、培养温度37℃、培养时间36 h、接种量5%。在优化条件下,细胞富集的锌含量有明显升高,为249.8μg/g,有机态锌占总量的80%以上。     

Factors Affecting Amine Production by a Selected Strain of Lactobacillus bulgaricus

Lactobacillus bulgaricus-52 showed maximum growth and amine production in MRS broth in 24 hr at 37°C. The optimum pH for the production of histamine, tyramine, and tryptamine by L. bulgaricus-52 was 5.0. Highest yields of the different amines were obtained in the absence of NaCI in the growth medium. A concentration of even 0.5% NaCI had a slight inhibitory affect on the synthesis of amines. A similar trend was observed in terms of amine production by L bulgaricus-52 in milk samples held at 37°C for different time intervals.