对双歧杆菌DM9227株的实验研究 Ⅱ.双歧杆菌DM9227株对小鼠的毒性试验研究

本文采用健康的昆明种小鼠,分别经灌胃、腹腔注射及静脉注射3种途径,对我们自己分离筛选的1株双歧杆菌DM9227株进行了毒性实验研究。菌种双歧杆菌DM9227株,分离自1健康的13个月的女婴的粪便。试验动物为健康昆明种小鼠,体重17—22g,雌雄各半,由大连医学院实验动物中心提供。     

对双歧杆菌DM9227株的实验研究——Ⅰ.双歧杆菌DM9227株的试管内生物拮抗作用的研究

本文对由健康婴儿分离的双歧杆菌DM9227株进行了试管内的生物拮抗试验。将双歧杆菌DM9227株分别与金黄色葡萄球菌、产毒性大肠杆菌及侵袭性大肠杆菌以一定的比例等量混合接种于PYG液体培养基中进行厌氧培养。试验证明双歧杆菌DM9227株能明显抑制上述3种细菌的生长繁殖,显示出较强的生物拮抗作用。拮抗机制可能与双歧杆菌DM9227株能产生一定量的醋酸和乳酸,降低培养基的pH,从而抑制该3种菌的生长有关。     

海藻糖对双歧杆菌DM8504菌株冷冻干燥保护效果的研究

本文就海藻糖对ＤＭ８５０４双歧杆菌的冻干保护效果进行了研究,考察了海藻糖浓度、保护剂溶液与菌泥混合时间对ＤＭ８５０４冻干存活率的影响,结果证实该保护剂对ＤＭ８５０４双歧杆菌有良好的冻干保护效果,优于其它保护剂。     

对双歧杆菌DM9227株的实验研究 Ⅲ.双歧杆菌DM9227株与蜡样芽胞杆菌DM423株共生关系的初步研究

本文对厌氧的双歧杆菌DM9227株与需氧的蜡样芽胞杆菌DM423株的共生关系进行了初步研究。将DM9227株与DM423株分别单独及按一定比例等量混合接种于BS肉汤内进行培养,间隔一定时间检测两菌在培养基内菌数的消长情况。结果表明DM423株与DM9227株之间呈偏生关系,即DM423株对DM9227株有促进作用,且在两菌比例适宜(1:100)情况下促进作用更明显,而DM9227株对DM423株有抑制作用。进一步将接种DM423株的Nb琼脂平板与接种DM9227株的BS琼脂平板在普通环境下一起密闭培养,可见厌氧的DM9227株生长良好,提示DM423株可能是通过消耗氧气,降低培养基的Eh,从而促进DM9227株生长的。     

青春双歧杆菌DM8504菌株对荷瘤小鼠体内NO诱生作用的研究

应用处死的青春双歧杆菌ＤＭ８５０４菌株皮下免疫荷瘤小鼠,按Ｇｒｉｅｓ反应原理测定一氧化氮（ＮＯ）的含量。结果表明,双歧杆菌能提高荷瘤小鼠体内ＮＯ的含量,较对照组显著升高,肿瘤组织的坏死程度在处理组与对照组之间也具有显著性差异。提示：在双歧杆菌抗肿瘤作用中,除ＴＮＦ—α外,ＮＯ也发挥重要作用。     

成都地区母乳双歧杆菌对婴儿肠道双歧杆菌构建的影响

目的 观察不同喂养方式婴儿肠道双歧杆菌的构建规律，初步探索母乳双歧杆菌与婴儿肠道双歧杆菌之间的相关性。方法 在四川大学华西第二医院纳入57对母婴志愿者，根据喂养方式分为母乳（BF）组（n=31）和混合喂养（MF）组（1月龄内添加奶粉时间>8 d,n=26），收集产妇产后0天、第30天的母乳，以及婴儿出生后0天、第7天、第30天的粪便。采用实时荧光定量PCR测定母乳和婴儿粪便中双歧杆菌属、角双歧杆菌（B. angulatum）、链双歧杆菌（B. catnulatum）、齿双歧杆菌（B. dentium）、短双歧杆菌（B.breve）、两歧双歧杆菌（B. bifidum）、长双歧杆菌长亚种（B. longum subsp. longum）、长双歧杆菌婴儿亚种（B.longum subsp. infantis）及青春双歧杆菌（B. adolescentis）的丰度。观察2组婴儿肠道双歧杆菌0―7―30天的构建规律；分析母乳双歧杆菌与婴儿肠道双歧杆菌之间的相关性。结果 0―7―30天2组婴儿肠道双歧杆菌构建过程存在差异。母乳双歧杆菌与婴儿肠道双歧杆菌存在相关：0 d时，BF组母乳B. a...     

婴幼儿粪便中双歧杆菌的分离及其菌株特性研究

为筛选具有潜在益生功能的双歧杆菌,本研究采用改良MRS培养基,从婴幼儿粪便中分离到5株菌株:AR499,AR667,AR668,AR669和AR610。通过16S r DNA测序分别鉴定为两歧双歧杆菌,短双歧杆菌,动物双歧杆菌,长双歧杆菌和假小链双歧杆菌。对其耐酸耐胆盐能力和黏附性能进行测试,结果表明,菌株AR499耐酸性较好,菌株AR610有较强的耐胆盐能力,菌株AR499的自动聚集能力和细胞表面疏水性都较高。实验表明,菌株AR499可作为一株耐受性和黏附性能较好的益生菌进一步深入研究,以期应用于优良双歧杆菌产品的开发。     

双歧因子对双歧杆菌增殖的影响

应用含有不同浓度的双歧因子(微维乐)的培养基对双歧杆菌进行了定性、定量观察。其结果表明,微维乐对双歧杆菌有明显的促进作用;在双歧杆菌制剂的生产过程中,添加一定量的微维乐,不仅可以提高双歧杆菌收率,而且还可以缩短菌种发酵时间。最佳添加量为1.5%,最佳发酵时间为1.5 h。     

抗生素对双歧杆菌影响的观察

本文观察了双歧杆菌对临床常用抗生素的敏感性及其Ｌ型形成和抗生素对动物体内双歧杆菌的影响,发现双歧杆菌对多种抗生素耐药或易形成Ｌ型。动物口服双歧杆菌同时给抗生素,６天后其粪便中仍有大量双歧杆菌或双歧杆菌Ｌ型存在,表明双歧杆菌可通过多种机制逃避抗生素的作用,在机体肠道内长期存在。     

双歧杆菌固定化的研究

双歧杆菌固定化的研究杨基础,刘佳（清华大学化学工程系,北京１０００８４）目前市场上的大多数双歧杆菌产品活菌量很低,保存不到一个月就全部死亡,这是当前亟待解决的问题之一。本文对双歧杆菌的固定化进行了研究,旨在提供一种制备高活性双歧杆菌片剂或胶囊的新方法...     

Strain gradient development in 3-dimensional extracellular matrix scaffolds during in vitro mechanical stimulation

This study analyzed strain variations in 3D ECM scaffolds using a membrane-adherent model (MM) and a direct elongation model (DM). Computational models were solved for target strains from 1 to 10% at varied scaffold thicknesses and intra-scaffold slices. DM strain profiles were uniform within the scaffold and independent of thickness. However, a wide range of strains developed with substantial volume experiencing significantly off-target strain. MM strain profiles varied throughout the scaffold, exhibiting significantly reduced average strain with increasing thickness. These findings are important for tissue engineering studies since biological responses are commonly attributed to a single strain level that only partially describes the mechanical condition, making it difficult to develop precise causal relationships. Spatial strain variations and reduced average strain may warrant targeted sampling for cell response and should be taken into consideration by investigators using large-volume 3D scaffolds when engineering mechanically sensitive tissues.     

DM423菌株诱变前后对吡哌酸的耐药性测定

为了研制一种对腹泻病人疗效快,又不造成菌群失调的药物。我们确定吡哌酸与DM423菌联合应用。首先把DM423菌株诱变成耐药菌株,经多次诱变筛选结果是,耐药量比原菌株提高了2000倍,耐药性相对稳定,耐药株生物学特性与原菌株相同。定名为DM423-1菌株。     

Effects of Bacterial Host and Dichloromethane Dehalogenase on the Competitiveness of Methylotrophic Bacteria Growing with Dichloromethane

Methylobacterium sp. strain DM4 and Methylophilus sp. strain DM11 can grow with dichloromethane (DCM) as the sole source of carbon and energy by virtue of homologous glutathione-dependent DCM dehalogenases with markedly different kinetic properties (the k_cat values of the enzymes of these strains are 0.6 and 3.3 s⁻¹, respectively, and the K_m values are 9 and 59 μM, respectively). These strains, as well as transconjugant bacteria expressing the DCM dehalogenase gene (dcmA) from DM11 or DM4 on a broad-host-range plasmid in the background of dcmA mutant DM4-2cr, were investigated by growing them under growth-limiting conditions and in the presence of an excess of DCM. The maximal growth rates and maximal levels of dehalogenase for chemostat-adapted bacteria were higher than the maximal growth rates and maximal levels of dehalogenase for batch-grown bacteria. The substrate saturation constant of strain DM4 was much lower than the K_m of its associated dehalogenase, suggesting that this strain is adapted to scavenge low concentrations of DCM. Strains and transconjugants expressing the DCM dehalogenase from strain DM11, on the other hand, had higher growth rates than bacteria expressing the homologous dehalogenase from strain DM4. Competition experiments performed with pairs of DCM-degrading strains revealed that a strain expressing the dehalogenase from DM4 had a selective advantage in continuous culture under substrate-limiting conditions, while strains expressing the DM11 dehalogenase were superior in batch culture when there was an excess of substrate. Only DCM-degrading bacteria with a dcmA gene similar to that from strain DM4, however, were obtained in batch enrichment cultures prepared with activated sludge from sewage treatment plants.     

表面活性剂对琼式不动杆菌LH-1-1降解溴氰菊酯的影响

旨在探究表面活性剂对菌株降解溴氰菊酯(Deltamethrin,DM)的影响。以前期筛选到具备DM较高降解能力的Acinetobacter junii LH-1-1为目标菌株,通过荧光光谱法测定了3种不同类型表面活性剂(CTAB、AES和Tween-20)的临界胶束浓度(Critical Micelle Concentration,CMC),并探究不同表面活性剂各CMC对A.junii LH-1-1生长、DM增溶作用和菌株降解DM的影响。结果显示,测得CTAB、AES、Tween-20的CMC分别为0.793 mmol/L、0.547 mmol/L和0.031 mmol/L;CTAB对菌株的生长无明显影响,AES对菌株生长有抑制作用,Tween-20对菌株的生长有一定的促进作用;CTAB、AES和Tween-20对DM均具有较强的增溶作用;且CTAB可显著提高A.junii LH-1-1对DM的降解率,当其含量为2 CMC,72 h时DM降解率达到98.20%,较未添加表面活性剂的对照组(阳性)降解率提高了24.31%。阳离子表面活性剂CTAB可显著提高A.junii LH-1-1对DM的降解。     

一株溴氰菊酯降解菌的分离鉴定及其降解条件优化

【背景】拟除虫菊酯类农药的降解已成为食品安全和环境卫生领域的研究热点,而生物降解被认为是一种绿色高效的解决方法。【目的】从长期受拟除虫菊酯类农药污染的草莓根系土壤分离一株溴氰菊酯(deltamethrin,DM)降解菌,并优化其培养基及降解条件,从而提高DM降解菌的降解效率。【方法】采用富集驯化、分离纯化法筛选DM降解菌,通过形态学和生理生化特征,以及16S rRNA基因序列分析进行鉴定。通过Plackett-Burman因素筛选试验、最陡爬坡试验和Box-Behnken试验优化菌株降解条件。【结果】筛选获得一株DM降解菌LH-1-1,96h对DM(100mg/L)的降解率为53.43%,经鉴定为琼氏不动杆菌(Acinetobacter junii);通过优化后,在DM浓度75mg/L、胰蛋白胨3 g/L、pH值6.8、硫酸铵1.5 g/L、氯化铁0.01 g/L、接种量为5%(体积比)、菌龄12 h、培养温度30℃条件下,菌株LH-1-1对DM降解率达82.36%,较未优化前提高了28.93%。【结论】A. junii LH-1-1具有较高的DM降解能力,该菌可为生物修复受DM或拟除虫菊酯类农药污染的环境提供优良的微生物资源。     

屎肠球菌活菌制剂的研究

对屎肠球菌活菌制剂的特性及功效进行研究和分析。方法：通过分离菌种、筛选、鉴定、初步确定一株具有调节血脂作用的屎肠球菌菌株。经过毒理学试验、调血脂功能试验及人体试食试验来观察该制剂的作用。结果：毒理学试验结果证明屎肠球菌DM891129菌株属无毒、弱蓄积,无遗传毒性。功效试验表明高中低剂量组均只有降低实验高脂血症大鼠血胆固醇的作用。结论：屎肠球菌活菌制剂具有调节血脂作用。     

Methylopila helvetica sp. nov. and Methylobacterium dichloromethanicum sp. nov.--novel aerobic facultatively methylotrophic bacteria utilizing dichloromethane

Eight strains of Gram-negative, aerobic, asporogenous, neutrophilic, mesophilic, facultatively methylotrophic bacteria are taxonomically described. These icl- serine pathway methylobacteria utilize dichloromethane, methanol and methylamine as well as a variety of polycarbon compounds as the carbon and energy source. The major cellular fatty acids of the non-pigmented strains DM1, DM3, and DM5 to DM9 are C18:1, C16:0, C18:0, Ccy19:0 and that of the pink-pigmented strain DM4 is C18:1. The main quinone of all the strains is Q-10. The non-pigmented strains have similar phenotypic properties and a high level of DNA-DNA relatedness (81-98%) as determined by hybridization. All strains belong to the alpha-subgroup of the alpha-Proteobacteria. 16S rDNA sequence analysis led to the classification of these dichloromethane-utilizers in the genus Methylopila as a new species - Methylopila helvetica sp.nov. with the type strain DM9 (=VKM B-2189). The pink-pigmented strain DM4 belongs to the genus Methylobacterium but differs from the known members of this genus by some phenotypic properties, DNA-DNA relatedness (14-57%) and 16S rDNA sequence. Strain DM4 is named Methylobacterium dichloromethanicum sp. nov. (VKM B-2191 = DSMZ 6343).     

Eiweißbiosynthese aus Lignozellulose enthaltenden Rohstoffen

The object of the presented studies was to determine the conditions of protein biosynthesis from lignocellulosic raw material using filamentous fungi. It was found that on beet pulp + 50% wheat straw, strain A. niger (A.n./61) shows the highest effectivity of protein biosynthesis. Using this strain, after 48-hour incubation the following results were obtained: increase in protein 4.43 g/100 g˙DM, daily protein increase coeffizient 2.22 g/100 g DM x 24 h, protein yield (based on the decrease in dry matter) 22.3% and cellulose utilization 37%. Upon use of a new strain CEL 2 and milled wheat straw as the substrate, the best results obtained after 74-hour incubation were as follows: increase in protein 1.82 g/100 g DM, daily protein increase coefficient 0.61 g/100 g DM x 24 h, protein yield 15,8% and cellulose utilization 22.0%. For rape straw and strain Sporotrichum pulverulentum, after 192-hour cultivation the following results were obtained: increase in protein 5.4 g/100 g DM, daily protein increase coefficient 0.68 g/100 g DM x 24 h, protein yield 14% and cellulose utilization 50.2%.