长双歧杆菌发酵培养基的优化

目的对长双歧杆菌液态发酵培养基进行优化。方法以长双歧杆菌（Bifidobacteriumlongum）为发酵菌株,以MRS培养基为基础培养基,以发酵液活菌数为指标,通过单因素添加实验考察发酵培养基的碳源和氮源的种类,并验证优化后培养基的效果。结果优化后培养基的最适碳源为葡萄糖,最适氮源为酪蛋白胨、牛肉蛋白胨、水解乳蛋白,发酵液活菌数达到2．09×10^9CFU／mL,比原MRS培养基（1．22×10^9CFU／mL）提高了71．30％。结论优化后培养基优于原MRS基础培养基,可应用于长双歧杆菌的液态发酵。     

Comparative study of Bifidobacteriumanimalis, Escherichiacoli, Lactobacilluscasei and Saccharomycesboulardii probiotic properties

The present work investigates some probiotic properties of four different microorganisms (Bifidobacterium animalis var. lactis BB-12, Escherichia coli EMO, Lactobacillus casei and Saccharomyces boulardii). In vitro and in vivo tests were carried out to compare cell wall hydrophobicity, production of antagonistic substances, survival capacity in the gastrointestinal tract of germ-free mice without pathological consequence, and immune modulation by stimulation of Küpffer cells, intestinal sIgA and IL-10 levels. In vitro antagonism against pathogenic bacteria and yeast was only observed for the probiotic bacteria B. animalis and L. casei. The hydrophobic property of the cell wall was higher for B. animalis and E. coli EMO, and this property could be responsible for a better ability to colonize the gastrointestinal tract of germ-free mice. Higher levels of sIgA were observed mainly for S. boulardii, followed by E. coli EMO and B. animalis, and only S. boulardii induced a significant higher level of IL-10. In conclusion, for a probiotic use, S. boulardii presented better characteristics in terms of immunomodulation, and B. animalis and L. casei for antagonistic substance production. The knowledge of the different probiotic properties could be used to choice the better microorganism depending on the therapeutic or prophylactic application.     

Comparative analysis of four <Emphasis Type="Italic">β</Emphasis>-galactosidases from <Emphasis Type="Italic">Bifidobacterium bifidum</Emphasis> NCIMB41171: purification and biochemical characterisation

Four different β-galactosidases (previously named BbgI, BbgII, BbgIII and BbgIV) from Bifidobacterium bifidum NCIMB41171 were overexpressed in Escherichia coli, purified to homogeneity and their biochemical properties and substrate preferences comparatively analysed. BbgI was forming a hexameric protein complex of 875 kDa, whereas BbgII, BbgIII and BbgIV were dimers with native molecular masses of 178, 351 and 248 kDa, respectively. BbgII was the only enzyme that preferred acidic conditions for optimal activity (pH 5.4–5.8), whereas the other three exhibited optima in more neutral pH ranges (pH 6.4–6.8). Na⁺ and/or K⁺ ions were prerequisite for BbgI and BbgIV activity in Bis–Tris-buffered solutions, whereas Mg⁺⁺ was strongly activating them in phosphate-buffered solutions. BbgII and BbgIII were slightly influenced from the presence or absence of cations, with Mg⁺⁺, Mn⁺⁺ and Ca⁺⁺ ions exerting the most positive effect. Determination of the specificity constants (k _cat/K _m) clearly indicated that BbgI (6.11 × 10⁴ s⁻¹ M⁻¹), BbgIII (2.36 × 10⁴ s⁻¹ M⁻¹) and especially BbgIV (4.01 × 10⁵ s⁻¹ M⁻¹) are highly specialised in the hydrolysis of lactose, whereas BbgII is more specific for β-d-(1→6) galactobiose (5.59 × 10⁴ s⁻¹ M⁻¹) than lactose (1.48 × 10³ s⁻¹ M⁻¹). Activity measurements towards other substrates (e.g. β-d-(1→6) galactobiose, β-d-(1→4) galactobiose, β-d-(1→4) galactosyllactose, N-acetyllactosamine, etc.) indicated that the β-galactosidases were complementary to each other by hydrolysing different substrates and thus contributing in a different way to the bacterial physiology.     

Genetic and structural comparison of linoleate isomerases from selected food‐grade bacteria

Aims: To advance the understanding of the molecular mechanisms underlying the capacity of bifidobacteria and lactic bacteria to convert linoleic acid (LA) into conjugated linoleic acid (CLA) by the linoleate isomerase (LI). Methods and Results: The potential LI enzymes of selected Lactobacillus, Bifidobacterium and Leuconostoc strains were compared at the genetic, amino acid sequence and functional levels. Genetic analysis was achieved by insertional mutagenesis and hybridization studies using a Lact. reuteri LI probe. Biotransformation studies monitored by gas chromatography showed that Bif. breve is a major CLA producer after the reference Lact. reuteri strain. The putative Bif. breve LI gene was PCR isolated and sequenced. Conclusions: The putative LI gene identified in this study seems essential for bacterial growth. Comparative studies indicate that the deduced protein is membrane bound and reveal the presence of several highly conserved domains among a wide range of Gram‐positive bacteria. Significance and Impact of the Study: Given the multiple health benefits of CLA, the capability of some bacteria to convert LA into CLA is of great relevance. Nevertheless, the yields of CLA remain low, and the regulation of the process is far from being understood. A deeper knowledge of this capacity by the genetic studies is revealing the identity of the LI and will eventually contribute to its control.     

Current status and application of lactic acid bacteria in animal production systems with a focus on bacteria from honey bee colonies

Lactic acid bacteria (LAB) are widely distributed in nature and, due to their beneficial effects on the host, are used as probiotics. This review describes the applications of LAB in animal production systems such as beekeeping, poultry, swine and bovine production, particularly as probiotics used to improve health, enhance growth and reproductive performance. Given the importance of honeybees in nature and the beekeeping industry as a producer of healthy food worldwide, the focus of this review is on the coexistence of LAB with honeybees, their food and environment. The main LAB species isolated from the beehive and their potential technological use are described. Evidence is provided that 43 LAB bacteria species have been isolated from beehives, of which 20 showed inhibition against 28 species of human and animal pathogens, some of which are resistant to antibiotics. Additionally, the presence of LAB in the beehive and their relationship with antibacterial properties of honey and pollen is discussed. Finally, we describe the use of lactic bacteria from bee colonies and their antimicrobial effect against foodborne pathogens and human health . This review broadens knowledge by highlighting the importance of honeybee colonies as suppliers of LAB and functional food.     

B-GOS对阿尔茨海默病转基因小鼠认知行为和抑郁情绪的影响*

目的: 观察新型低聚半乳糖(B-GOS)对APP/PS1/tau阿尔茨海默病转基因小鼠认知行为和抑郁情绪的影响。方法: 选用5月龄雄性APP/PS1/tau AD转基因小鼠和C57BL/6J对照小鼠,分为C57+Vehicle组、C57+B-GOS组、APP/PS1/tau+Vehicle组和APP/PS1/tau+B-GOS组,每组10只。B-GOS连续给予5个月后,依次采用旷场实验、新物体识别实验、Y迷宫实验、Morris水迷宫实验、悬尾实验、强迫游泳实验和条件恐惧实验,检测各组小鼠的认知行为表现和抑郁情绪变化。结果: ① 旷场实验:APP/PS1/tau+Vehicle组小鼠在旷场中央区域的活动时间百分比显著低于C57+Vehicle组小鼠(P＜0.01),经过B-GOS干预后显著升高(P＜0.05)。② 新物体识别实验:APP/PS1/tau+Vehicle组小鼠的新物体识别指数(NOI)显著低于C57+Vehicle组小鼠(P＜0.01), 经过B-GOS干预后显著升高(P＜0.05)。③ Y迷宫实验:APP/PS1/tau+Vehicle组小鼠的自发交替正确率显著低于C57+Vehicle组小鼠(P＜0.01),经过B-GOS干预后显著升高(P＜0.01)。④ 经典水迷宫实验:APP/PS1/tau+Vehicle组小鼠在第4日和第5日的逃避潜伏期显著长于C57+Vehicle组小鼠(P＜0.01),经过B-GOS干预后均显著缩短(P＜0.05);在空间探索阶段,APP/PS1/tau+Vehicle组小鼠的目标象限游泳时间百分比和穿越平台次数均显著低于C57+Vehicle组小鼠(P＜0.01),经过B-GOS干预后均显著增加(P＜0.01)。⑤ 悬尾试验和强迫游泳实验:APP/PS1/tau+Vehicle组小鼠的不动时间百分比均显著高于C57+Vehicle组小鼠(P＜0.01),经过B-GOS干预后均显著降低(P＜0.01)。⑥ 条件恐惧实验:在条件刺激(CS)作用前,各组小鼠的僵直比率无统计学差异(P＞0.05)。CS作用后,APP/PS1/tau+Vehicle组小鼠的僵直比率显著低于C57+Vehicle 组小鼠(P＜0.01),经过B-GOS干预后均显著上升(P＜0.01)。结论: B-GOS能够较大程度地逆转APP/PS1/tau小鼠的认知行为损伤,并减轻其抑郁情绪。     

益生菌联合抗生素对抗生素相关性腹泻新生儿肠道菌群的影响

目的探讨酪酸梭菌二联活菌散剂联合头孢唑肟钠对抗生素相关性腹泻新生儿肠道菌群的影响。方法选取2017年1月至2019年12月期间我院收治的80例抗生素相关性腹泻新生儿为研究对象,采用随机数字法将其分为对照组(n=40)与观察组(n=40)。对照组患儿采用头孢唑肟钠治疗,观察组在对照组的基础上联合酪酸梭菌二联活菌散剂治疗,治疗72 h后比较两组患儿治疗效果及肠道菌群数量。结果治疗72 h后,观察组患儿肠鸣音恢复时间、腹痛缓解时间、腹泻消失时间、腹胀消失时间及住院时间均短于对照组(t=7.873、6.807、5.096、4.977、4.794,均P0.001),临床有效率高于对照组(95.00%vs 82.50%,χ~2=4.486,P=0.034)。治疗72 h后,观察组患儿肠道大肠埃希菌数量低于对照组(t=3.924,P0.001),而乳杆菌、双歧杆菌数量均高于对照组(t=2.169、3.016,P=0.033、0.003)。结论酪酸梭菌二联活菌散剂联合头孢唑肟钠可通过改善肠道菌群数量发挥治疗新生儿抗生素相关性腹泻的效果。     

Synthesis of 2-Tetrafluoroethyl-pseudooxazolone-(5)

The study describes the inhibitory activity of natural piericidins and related compounds, including synthetic analogues, to the electron transport system of mitochondria. Consideration of the structure-activity relationships led to the proposing of a structural unit I that was essential to inhibitory activity.     

1-Kestose consumption during pregnancy and lactation increases the levels of IgA in the milk of lactating mice

To examine the effect of dietary supplementation with 1-kestose on the IgA levels in milk, BALB/c mice were fed diets with or without 5% 1-kestose during pregnancy and lactation. The total and specific IgA levels in the milk were measured at 7 and 14?days after delivery. A two-way ANOVA with repeated measures resulted in a significant effect of 1-kestose-supplementation on total IgA concentrations (p?<?0.05) and the level of anti-Bacteroides IgA (p?<?0.05). A significant positive correlation was found between the mean count of Bacteroides spp. in maternal feces and the total IgA concentration in maternal milk (r?=?0.55, p?<?0.05), suggesting a potential link between the gut and mammary gland immune system. In conclusion, this study demonstrated the effects of dietary prebiotics on milk IgA production.