模拟人体胃肠道环境筛选益生乳杆菌

【目的】筛选具有益生特性的乳杆菌作为保健型酸奶的候选菌株。【方法】从健康人肠道和奶豆腐中分离筛选出耐受人工胃液的乳杆菌,对其进行体外益生特性(人工胃肠液耐受性、胆盐耐受性、抑菌活性及胆固醇降解能力)研究。【结果】从在乳杆菌分离培养基上有溶钙圈的41株菌株中筛选出5株耐酸、耐人工胃液较强的菌株,经16S rR NA基因测序鉴定,其中3株为乳杆菌,分别命名为植物乳杆菌Lp MT-3、植物乳杆菌Lp MT-5和唾液乳杆菌LsA F-7。在人工胃液中3株菌的耐受力均强于商品化的对照菌株LGG(鼠李糖乳杆菌GG);转入肠液4 h后直至26 h,Lp MT-5存活率基本稳定在45%左右,仅次于LGG。胆盐浓度为0.10%时,3株乳杆菌的耐胆盐能力均强于LGG;胆盐浓度为0.20%时,Lp MT-3和LsA F-7仍能存活。3株乳杆菌均具有抑菌活性,对粪肠球菌的抑制最明显,其次是金黄色葡萄球菌,对大肠杆菌、沙门氏菌的抑制作用较差。3株乳杆菌对胆固醇的清除效力依次为Lp MT-3LpM T-5Ls AF-7;清除率依次为Ls AF-7Lp MT-3LpM T-5。【结论】筛选出3株适应人体胃肠液环境、耐胆盐、抑菌及降胆固醇活力强的乳杆菌,可作为进一步开发新的益生菌产品和保健型酸奶的菌株。     

新疆传统发酵乳品中乳酸菌与 酵母菌的益生特性

目的观察新疆传统发酵乳品中分离的14种菌株的生长特点及产酸能力,筛选出具有较强耐胆盐能力,并能在人工胃肠液中存活的菌株。方法对10株乳酸菌和4株酵母菌进行生长曲线、pH、耐胆盐能力和耐人工胃肠液检测。结果 10株乳酸菌和4株酵母菌具有良好的生长曲线和产酸能力;马乳酒样乳杆菌具有较强的耐胆盐能力;希氏乳杆菌、马乳酒样乳杆菌、乙醇假丝酵母和东方伊萨酵母具有较强的耐人工胃液能力;乳酸乳球菌、哈尔滨乳杆菌、瑞士乳杆菌、马乳酒样乳杆菌、乙醇假丝酵母和东方伊萨酵母具有较强的耐人工肠液能力。结论 10株乳酸菌和4株酵母菌具有优良的益生特性,有望成为益生菌制剂的备用菌株。     

普洱茶中微生物的筛选及其安全性初步评价

目的在对普洱茶中微生物筛选和鉴定基础上对蜡样芽胞杆菌毒素基因的分布、普洱茶下调毒素基因的表达和改善肠上皮细胞的损伤进行研究。方法分别采用无菌水和沸水泡制普洱茶,获得分离株,通过16SrDNA测序以及生理生化试验确定其归属;对所筛选的菌株进行耐模拟胃肠液能力评价和毒力基因的检测;采用细胞实验和荧光定量PCR技术,研究普洱茶对蜡样芽胞杆菌毒素的抑制作用。结果无菌水浸泡普洱茶获得的45株菌中44株为芽胞杆菌属,沸水浸泡获得的7株菌均为蜡样芽胞杆菌(FBCE01、FBCE06、FBCE10、FBCE14、FBCE20、FBCE26和FBCE29),多重PCR技术结果表明其分别含有毒力基因cytK、nheA和hblD的2种或3种。耐模拟胃肠液实验表明,7株菌均具有很强的耐模拟胃肠液消化能力;细胞实验结果发现,普洱茶汤能显著降低蜡样芽胞杆菌对Caco-2细胞的粘附(P0.05);MTT实验结果显示,普洱茶能有效降低蜡样芽胞杆菌对细胞的损伤;荧光定量PCR技术结果进一步说明,普洱茶使蜡样芽胞杆菌肠毒素的mRNA表达水平下调。结论普洱茶具有抑制蜡样芽胞杆菌毒素的作用。     

铜绿假单胞菌体外抑菌活性研究

目的 观察铜绿假单胞菌抗菌物质对鲍曼不动杆菌等细菌的体外抑菌效果.方法 用交叉条带实验方法检测了铜绿假单胞菌对鲍曼不动杆菌、耐甲氧西林表皮葡萄球菌和粪肠球菌的体外抑制活性.结果 铜绿假单胞菌对鲍曼不动杆菌、耐甲氧西林表皮葡萄球菌和粪肠球菌体外抑菌活性良好,10株铜绿假单胞菌中,有8株对鲍曼不动杆菌的抑制率均达到了100％.另外有8株对耐甲氧西林表皮葡萄球菌的抑菌率均为100％;有6株对粪肠球菌的抑菌率为100％.结论 铜绿假单胞菌对上述3种致病菌具有较强的抗菌活性,具有开发前景.     

栀子豉汤所含优势益生菌群的研究

目的考察不同煎煮方法及人工胃液、肠液对栀子豉汤所含优势菌群的影响,基于芽胞杆菌的整肠作用探讨栀子豉汤的作用机制。方法采用先煎栀子再煎淡豆豉(方法一)及两药同时煎煮(方法二)得到不同的栀子豉汤溶液,在营养琼脂培养基上培养及菌落计数,通过Biolog自动微生物鉴定系统对分离菌株进行鉴定,并考察人工胃液、肠液对栀子豉汤所含优势菌群数量的影响。结果方法一制备的栀子豉汤所含优势菌数量更多,为(2.55±0.02)×10~5 CFU/mL,以枯草芽胞杆菌为主;栀子豉汤经人工胃液、人工肠液作用后,优势菌又大量繁殖。结论栀子豉汤可能通过其所含益生芽胞杆菌的整肠作用而发挥药效。     

东北地区耐盐芽胞杆菌筛选统计及初步鉴定

采用温度筛选与表面定向培养相结合的方法对东北地区土壤中可培养耐盐芽胞杆菌进行分离和筛选,得到137株芽胞杆菌,其中耐盐芽胞杆菌74株,占总芽胞杆菌数量的54%,最适盐浓度均为1%,耐盐能力在4%-14%之间。通过扩增耐盐菌株的16S rRNA基因序列,对其进行分子鉴定和分类,获得东北地区土壤中可培养的耐盐芽胞杆菌的多样性信息。通过同源性比对和耐盐性差异,确定36株差异耐盐芽胞杆菌,分属于芽胞杆菌属中的7个种。其中多数菌株为苏云金芽胞杆菌(Bacillus thuringiensis)(14株,占总数38.9%,最高耐盐性在4%-9%NaCl之间)。其次依次为蜡样芽胞杆菌(Bacillus cereus)(7株,19.4%,4%-8%NaCl),枯草芽胞杆菌(Bacillus subtilis)(7株,19.4%,8%-11%NaCl),炭疽芽胞杆菌(Bacillus anthracis)(4株,11.1%,5%-7%NaCl),弯曲芽胞杆菌(Bacillus flexus)(2株,5.6%,9%-14%NaCl),球形芽胞杆菌(Bacillus sphaericus)(1株,2.8%,5%NaCl)和阿氏芽胞杆菌(Bacillus aryabhattai)(1株,2.8%,6%NaCl)。弯曲芽胞杆菌和枯草芽胞杆菌的耐盐能力较好。从中选取3株代表菌株,明确了其培养特性、形态特征及生理生化特性,并对其分别进行了系统发育分析。     

耐酸鼠李糖乳杆菌的驯化筛选研究

目的通过驯化以及筛选,得到能够耐酸的鼠李糖乳杆菌菌株。方法将鼠李糖乳杆菌三级发酵菌液接入人工胃液中驯化,获得耐酸菌株。经连续6次驯化筛选,以及人工肠液耐受性实验。结果鼠李糖乳杆菌GD0029在人工胃液中的存活率可达42.93%,比驯化前提高了2.7倍,其对人工肠液也具有较好的耐受性。结论筛选得到的鼠李糖乳杆菌菌株具有很高的应用价值。     

脱除游离棉酚乳酸菌的分离鉴定及益生性能研究

从藜麦茎叶样品中筛选分离出乳酸菌株,测定菌株脱除游离棉酚能力,通过人工胃液、人工肠液耐受实验、抑菌实验、抗生素敏感实验及表面特性研究菌株各项性能,并通过生理生化及16S rDNA法对菌株进行鉴定。结果表明,筛选出1株高效游离棉酚脱除乳酸菌LR002,其游离棉酚脱除率为62.87%,该菌株具有高效的耐人工胃液、肠液效果,且具有广谱抑菌作用,对抗生素不敏感,经鉴定该菌株为植物乳杆菌（Lactobacillus plantarum）。本研究旨在筛选出高效游离棉酚脱除乳酸菌菌株,为棉粕在畜禽生产中的合理利用提供参考。     

几株乳酸菌益生潜力及降胆固醇的研究

采用体外试验方法研究7株乳酸菌和双歧杆菌对人体消化道不良环境的抵抗能力、在肠道上皮的黏附定植能力及其降胆固醇潜力。结果表明:受试菌对CCL-187细胞粘附能力存在显著差异(P<0.05),粪肠球菌M1粘附能力最强;各菌对胃液和胰液都有较强耐受能力,在模拟胃液和胰液中分别培养3h和4h后仍能保证95%以上存活;在含胆汁培养基中受到不同程度抑制,但都能存活;受试菌在生长过程中能够使环境中胆固醇降低从25%～54%不等,粪肠球菌A30和A31和嗜酸乳杆菌A878和PB1能使胆固醇降低40%以上,是良好的降胆固醇备选菌株。     

饲料乳酸菌的分离鉴定及优良菌株筛选

对从饲料玉米、高粱、麦秆及棉花中筛选出的乳酸菌进行分类鉴定和综合性分析。用MRS+CaCO3固体培养基从棉花中分离出乳酸菌18株、高粱中30株、饲料玉米中18株、麦秆中18株。经形态学、生理生化试验进行初步鉴定并按产酸试验,耐盐及耐酸试验挑选出32株产酸率强的乳酸菌对其进行16S rDNA分子鉴定。结果显示,32株菌都具有良好的耐盐、耐酸能力;经生理生化和16S rDNA基因序列鉴定可知32株乳酸菌分属于两个属,即乳杆菌属、肠球菌属,4个种,即干酪乳杆菌(Lactobacilluscasei)、肠道球菌(Entercoccus faecium)、植物乳杆菌(Lactobacillus plantarum)、海氏肠球菌(Entercoccus hirae)。4种饲料原料中肠道球菌普遍存在。除了这种乳酸菌以外,棉花有干酪乳杆菌、植物乳杆菌、海氏肠球菌,玉米和麦秆内有植物乳杆菌。从饲料中筛选出4株具有较强产酸能力的乳酸菌,可进一步研发成青贮饲料添加剂。     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.