紫外诱变原生质体选育D-核糖生产菌株

以D-核糖产生菌枯草芽孢杆(Bacillus subtilis)B941为出发菌株,采用紫外诱变原生质体的方法,获得了4株可以在含有6．0％D-核糖的培养基上生长的D-核糖高产菌株,其摇瓶发酵产糖达55．0g／L左右。通过摇瓶发酵试验,研究了D-核糖高产菌株Buvp-24的遗传稳定性。研究结果表明,经多次传代,菌株Buvp-24的发酵产糖能力及对发酵产物D-核糖的耐受性没有改变,有望应用于工业生产中。     

D-核糖生产菌的原生质体诱变及其发酵培养

目的:筛选出莽草酸、转酮醇酶双重营养缺陷型的D-核糖生产菌枯草芽胞杆菌,以提高D-核糖的产量。方法:采用化学诱变剂乙基磺酸甲烷(EMS)对野生型D-核糖生产菌的原生质体进行诱变,并从D-核糖合成途径对发酵培养基进行优化设计。结果:摇瓶发酵D-核糖平均产量为52.2g/L;获得的B.sems-10菌株具有良好的遗传稳定性,D-核糖产量高达67.5g/L。结论:通过对D-核糖生产菌原生质体的EMS诱变,筛选出了高产、遗传性状稳定的营养缺陷型B.sems-10菌株,为进一步提高产量奠定了基础。     

紫外诱变耐糖选育D-核糖高产菌株

以D-核糖产生菌枯草芽胞杆菌B2502为出发菌株,经紫外诱变、耐糖选育,得到1株可在D-核糖浓度达6%的肉汤液体培养基中生长的菌株B2502-2。其D-核糖产量提高37%,菌体生长达到对数期的时间缩短3 h,耐糖性比出发菌株提高了50%。     

玉米浆对转酮酶缺陷型短小芽孢杆菌菌株成链的影响

在研究D 核糖发酵过程中发现 ,培养基中玉米浆的含量直接影响着菌体的形态及D 核糖产量。在不同培养基中加入不同浓度的玉米浆 ,镜检菌株的生长情况 ,并测定发酵培养基中D 核糖的产量。研究表明 ,转酮酶缺陷是突变株在菌体生长过程中出现链状的内因 ,而玉米浆中所含的芳香族氨基酸是转酮酶缺陷型突变株在生长过程中出现链状的外因。     

D-乳酸产生菌的研究进展

D-乳酸作为一种重要的工业有机酸,是许多手性物质的中间体,特别是高光学纯度D-乳酸因其可以提高聚乳酸材料的性能而广泛应用。微生物发酵法是目前D-乳酸的主要生产方法,而菌种在发酵生产中占有非常重要的地位,是决定整个生产过程的关键。就近几十年来产D-乳酸常用菌株、菌种进化、研究方法、存在问题及前景做一综述。     

发酵法生产D-核糖

Ｄ－核糖是一种重要的生理物质,可用于合成维生素Ｂ２,风味提高剂以及多种核酸药物等,具有广泛的应用前景,由于化学合成法存在污染公害,故近年来各国相继研究微生物发酵法生产Ｄ－核糖,并致力于工业化生产。本文对国内外Ｄ－核糖的研究进展作了综述,并对Ｄ－核糖的提取方法进行了探讨。     

生物材料表面蛋白质微图形对人体软骨细胞形态及蛋白表达的影响

主要研究采用微接触印刷术在生物材料表面制备的细胞外基质蛋白微图形对人体软骨细胞粘附、铺展以及蛋白质表达等细胞行为的影响．研究结果表明,蛋白质微图形表面对细胞的粘附、铺展、排列以及细胞蛋白质表达具有明显的影响．细胞优先粘附在微图形蛋白区域,微图形形状以及尺度明显影响细胞的粘附形态以及铺展程度,同时也影响细胞生长过程中的Ⅱ型与Ⅵ型胶原蛋白的表达,细胞的铺展行为与细胞的蛋白质表达具有一定的正相关性,铺展较好的细胞表现出更好的Ⅱ型与Ⅵ型胶原蛋白表达．结果表明,通过在材料表面制备细胞外基质蛋白微图形可以有效调控人体软骨细胞的生长行为与功能．     

微生物发酵过程的多种培养技术

微生物发酵是一种很复杂的生化过程,除了与菌种的生产性能有关,还与培养基的配比、原料的质量、灭菌条件、发酵条件和过程控制等有密切关系.传统的微生物发酵过程主要有分批、半连续、分批补料、连续发酵等几种方式,不同的培养技术各有其优缺点.了解生产菌种在不同的生产工艺条件下的细胞生长、代谢和产物合成的变化规律将有助于发酵过程烫的控制.     

丝状真菌液体深层发酵过程菌丝聚集的调控机制

丝状真菌是微生物发酵产品的重要表达体系,其液体深层发酵过程的典型特征是环境因素显著影响菌丝聚集,菌丝聚集影响发酵体系流变特性,进而影响质量传递、热量传递和动量传递,最终影响目标产物生物合成和生产效率。文中首先综述了丝状真菌形态调控的方法和策略,在此基础上针对丝状真菌菌丝生长和聚集过程的两大典型特征——顶端延伸生长和分枝生长,综述和展望了钙信号传导途径和几丁质生物合成途径对调控菌体聚集这一形态的重要意义。     

枯草杆菌JSIM—1018糖代谢突变株积累D—核糖研究

从收集的Bacillus,Brevibacterum,Corynebacterium,Pseudomonas,Arthrobacter等属菌种中进行D-核糖产生菌的筛选,对其中BacillusSM-18菌株用紫外线和甲基磺酸乙酯诱变,选育到莽草酸营养缺陷型突变株JSIM-1018．发酵产物经物理、化学鉴定为D-核糖．某些有机氮源如酵母粉、玉米浆、牛肉膏、蛋白陈以及某些芳香族氨基酸对突变株积累D-核糖有促进作用。在以葡萄糖为碳源的培养液中,摇瓶发酵D-核糖最高可达929／L,3000L发酵罐中试D-核糖最高可达81．759／L,平均在64g／L以上,葡萄糖基本耗尽。     

Investigation of the mechanism of temperature sensitivity of the electroreceptors of ampullae of lorenzini

In experiments on Black Sea skates (Raja clavata), the potential of the receptor epithelium of the ampullae of Lorenzini and spike activity of single nerve fibers connected to them were investigated during electrical and temperature stimulation. Usually the potential within the canal was between 0 and –2 mV, and the input resistance of the ampulla 250–400 k. Heating of the region of the receptor epithelium was accompanied by a negative wave of potential, an increase in input resistance, and inhibition of spike activity. With worsening of the animal's condition the transepithelial potential became positive (up to +10 mV) but the input resistance of the ampulla during stimulation with a positive current was nonlinear in some cases: a regenerative spike of positive polarity appeared in the channel. During heating, the spike response was sometimes reversed in sign. It is suggested that fluctuations of the transepithelial potential and spike responses to temperature stimulation reflect changes in the potential difference on the basal membrane of the receptor cells, which is described by a relationship of the Nernst's or Goldman's equation type.I. P. Pavlov Institute of Physiology, Academy of Sciences of the USSR, Leningrad. I. M. Sechenov, Institute of Evolutionary Physiology and Biochemistry, Academy of Sciences of the USSR, Leningrad. Pacific Institute of Oceanology, Far Eastern Scientific Center, Academy of Sciences of the USSR, Vladivostok. Translated from Neirofiziologiya, Vol. 12, No. 1, pp. 67–74, January–February, 1980.     

Determination of stoichiometry of radioiodination of proteins

A sensitive method for the detection of small quantities of hydrophobic antioxidant free radical scavengers such as butylatedhydroxytoluene (BHT) and butylatedhydroxyanisole (BHA) in aqueous samples is described. The procedure involves extraction of the hydrophobic free radical scavenger into an organic solvent phase, followed by the subsequent reaction of an aliquot of this extract with the stable cation radical tris(p-bromophenyl)amminium hexachloroantimonate (TBACA). In experiments with BHT and BHA, the loss of TBACA absorbance at 730 nm was found to be linearly proportional to the amount of antioxidant added, with quantities of BHT as small as 200 pmol being easily detectable. In aqueous suspensions of dimyristoylphosphatidylcholine vesicles, assays of the aqueous BHT concentration showed that BHT partitioned strongly into the membrane phase, achieving very high BHT/phospholipid ratios. For a given concentration of BHT, partitioning into the membrane phase was greater in large, multilamellar liposomes than in either small, single-walled vesicles or in purified rat brain synaptic vesicle membranes. Direct assay of BHT and BHA in phospholipid membranes, however, was complicated by a nonspecific interaction between TBACA and the phospholipid.