嗜盐微生物

高盐环境通常是指那些盐浓度高于海水的环境．在这些环境中能够生存的微生物可划分为三类：一“类是能耐受一定浓度的盐溶液,但在无盐存在条件下生长最好的菌称为耐盐菌．第二类是一定浓度的盐为菌体生长所必需,且在一定浓度的盐溶液中生长最好,称为嗜盐菌．在盐浓度从零至饱和的盐溶液中均能生长,在一定浓度的盐溶液中生长最好的特殊类群称为多能盐生苗。依据嗜盐浓度的不同,嗜盐菌又可分为轻度嗜盐菌（最适盐浓度0．2—0．smol／L）、中度嗜盐菌（最适盐浓度0．5—2．omol／L）和极端嗜盐菌（最适盐浓度＞3mol／U,其中部分极端嗜…     

微生物嗜盐酶盐适应性的分子结构基础研究

由高盐环境中生长的微生物里分离出的嗜盐酶在高盐度下仍然具有催化活性,工业上具有良好的应用前景。一些嗜盐酶已被克隆纯化出来,它们的分子结构特点也已经被广泛研究。该文从嗜盐酶的蛋白质序列和结构特征等方面综述了嗜盐酶嗜盐的分子结构基础研究进展,分析了存在的问题并对未来工作提出了展望。研究嗜盐酶盐适应性的分子基础,可以为新的功能蛋白的发展和鉴定提供依据。     

嗜热微生物酶的嗜热机制及应用研究进展

从细胞膜组分、蛋白质结构、遗传物质、钨元素等方面阐述了嗜热微生物酶的嗜热机制 ,并简要介绍了其应用的研究进展。     

嗜盐菌的嗜盐机制

嗜盐菌是生活在高盐环境中的细菌。它们的细胞结构和生理机能特殊,要求有高盐浓度维持其生存;同时,它们的细胞膜结构和细胞内的溶质,都能适应高盐环境。     

嗜盐脂肪酶产生菌的筛选及其粗酶性质

从内蒙古锡林浩特地区盐湖菌种样品分离获得一株嗜盐脂肪酶高产菌, 结合生理生化试验和16S rDNA序列分析结果, 鉴定并命名为Haloterrigena thermotolerans Z4。该菌最适生长NaCl浓度为3.5 mol/L, 最高生长温度为60°C, 属于嗜盐耐热古生菌。粗酶性质研究表明, 金属离子(Ba2+、Fe2+、Cu2+)对酶有激活作用, 酶活不同程度的提高了20%~30%; 该酶受EDTA的抑制, 酶活下降了20%, 受PMSF的完全抑制。该酶对NaCl有较高的依赖专一性, 至少需要0.5 mol/L NaCl维持活性并且高浓度NaCl可以提高其耐热水平。醇类物质对于提高酶的热稳定性有一定作用, 丙三醇效果最好。该酶对短链底物对硝基苯酚丁酸酯(p-NPB)的最适水解条件为：pH 8.0、70°C、3.5 mol/L NaCl; 而对长链底物对硝基苯酚十六酸酯(p-NPP)的最适水解条件为：pH 8.0、80°C、2.5 mol/L NaCl。     

嗜盐微生物在环境修复中的研究进展

人类活动产生的污染物,使一些天然盐环境遭受不同程度的污染,或者使环境受到污染物与高盐的双重污染。在高盐条件下,非嗜盐微生物的代谢会受到抑制,其生物修复效率明显降低,甚至丧失修复能力。嗜盐微生物则能够在高盐环境中栖息繁殖,凸显其修复被污染高盐环境的生物学效率和广阔的应用前景。就嗜盐微生物降解石油烃、芳香烃衍生物和有机磷等污染物的研究进展进行了综述和讨论。     

嗜盐微生物的工业应用研究及进展

嗜盐微生物是一类生长于高盐环境的微生物,在新型生物化工产业及生物修复领域具有突出的应用潜力。本文简要介绍了嗜盐微生物的种类、生理特性,着重阐述了嗜盐微生物产生的活性物质在工业生产上的应用价值和开发前景,总结了近年来国内外在嗜盐微生物工业应用上的研究进展,对嗜盐微生物的应用研究做了概括。     

极端嗜盐古菌蛋白类抗生素——嗜盐菌素

古菌 (Ａｒｃｈａｅａ)是一类与细菌及真核生物显著不同的生命的第三种形式[1] ,大多生活在极端或特殊环境 ,主要包括产甲烷古菌 (ＭｅｔｈａｎｏｇｅｎｉｃＡｃｈａｅａ)、极端嗜盐古菌 (ＥｘｔｒｅｍｅｌｙＨａｌｏｐｈｉｌｉｃＡｒｃｈａｅａ)和极端嗜热古菌 (ＥｘｔｒｅｍｅｌｙＴｈｅｒｍｏｐｈｉｌｉｃＡｒｃｈａｅａ)等三大类。极端古菌是极端环境微生物的重要成员 ,也是极端环境微生物资源开发的重要领域。其中 ,嗜盐古菌可产生一类蛋白类抗生素 ,称为嗜盐菌素 (ｈａｌｏｃｉｎ)。与细菌素相似[2 ] ,嗜盐菌素是由质粒编码、核糖体合…     

安徽定远盐矿可培养嗜盐微生物多样性

【背景】嗜盐微生物多生活于高盐环境,具有独特的生理代谢特征,是一类重要的极端环境微生物资源。【目的】为更好地认识我国陆相盐矿的嗜盐微生物多样性组成,更好地开发利用嗜盐微生物资源积累丰富的微生物菌种。【方法】对安徽定远盐矿盐芯样品进行嗜盐微生物的纯培养分离,并对所分离菌株进行基于16SrRNA基因的测序和序列相似性分析,并对所分离菌株进行物种多样性分析。在此基础上,对代表菌株进行菌落形态和耐盐度及酶活测定。【结果】通过纯培养共分离获得了嗜盐微生物264株,其中嗜盐古菌150株,占56.8%;嗜盐细菌114株,占43.2%。嗜盐古菌物种分别来自于Halorubrum、 Halopenitus、 Haloterrigena、 Natrinema、 Natronoarchaeum和Natronomonas等6个属;嗜盐细菌物种分别来自于Pseudomonas、Aliifodinibius、Halobacillus、Halomonas和Halospina等5个属。通过代表菌株的酶活平板检测,发现产胞外蛋白酶菌株1株,酯酶1株,淀粉酶2株;能液化明胶菌株2株。在物种多样性组成方面,发现嗜盐古菌的物种多样性指数高于嗜盐细菌。【结论】本研究对我国安徽定远陆相盐矿的可培养嗜盐微生物多样性进行探究,积累了丰富的嗜盐微生物菌株资源。     

极端嗜盐菌的特性及其应用前景

主要介绍极端嗜盐菌的嗜盐机理、细菌视紫红质(bR)和嗜盐菌素的研究进展,然后对其在环境生物治理、生物电子和医药工业等领域的应用研究进行总结和展望。     

Mechanism and Atomic Structure of Superoxide Dismutase

The active site Cu ion in Cu,Zn superoxide dismutase is alternately oxidized and reduced during the enzymatic dismutation of superoxide to hydrogen peroxide and molecular oxygen. For oxidized Cu,Zn superoxide dismutase, an atomic structure has been determined for the human enzyme at 2.5 A resolution. The resolution of the bovine enzyme structure has been extended to 1.8 A. Atomic resolution data has been, collected for reduced and inhibitor-bound Cu,Zn superoxide dismutases. and the interpretation of the' electron density difference maps is in progress. The geometry and molecular surfaces of the active sites in these structures, together with biochemical data, suggest a specific model for the enzyme mechanism. Similarities in the active site geometry of the Mn and Fe superoxide dismutases with the Cu.Zn enzyme suggest that dismutation in these enzymes may follow a similar mechanism.     

Distribution of the 7S Proteins in Soybean Globulins by Gel Filtration with Sephadex G-200

The level of isocitrate lyase, an enzyme of glyoxylate cycle, in Candida tropicalis was enhanced at the later period of growth when the yeast was cultivated in a semisynthetic glucose medium. On the other hand, such increase in the enzyme activity was not observed in C. lipolytica grown under the same conditions. In the case of C. tropicalis, high concentrations of glucose remaining in the medium permitted the increase in the enzyme activity and the addition of ethanol, one of the major products from glucose, to the glucose medium did not stimulate the enzyme formation, indicating that the enhanced enzyme level in the yeast was not merely attributable to the release from the repression by glucose or to the induction by ethanol. Biotin, one of the growth-stimulating factors for C. tropicalis, affected markedly the level of isocitrate lyase. That is, the supplementation of biotin to the synthetic glucose medium inhibited completely the increase in the enzyme activity, and reversely the absence of biotin stimulated the enzyme formation in the glucose-assimilating cells. Thiamine, another growth-stimulating factor for C. tropicalis, did not show any effect on the level of isocitrate lyase in the yeast. The level of isocitrate lyase in C. lipolytica growing on glucose was not affected by biotin added exogenously.     

Metabolism of Histidine in Growing Rats at Various Dietary Protein Levels

The metabolic fate of the carbon skeleton of l-(U-¹⁴C)-histidine has been investigated in growing rats fed diets containing different percentages of protein calories (0, 5, 10, 15 and 30 PC%) at 410 kcal of metabolizable energy per 100 g diet.

The incorporation of ¹⁴C into body protein at 12 hr after injection of ¹⁴C-histidine was about 70% of the dose in rats fed 0 to 10 PC% diets, though the value was reduced in rats fed higher PC% diets. The expired ¹⁴CO₂ production was depressed in the low protein groups, and it showed an inverse pattern to that of ¹⁴C incorporation into body protein. Urinary excretion of ¹⁴C was about 20% of the dose in all dietary groups. The activities of hepatic histidase, urocanase and histidine-pyruvate aminotransferase were increased in the 30 PC% group.

These results indicate that the metabolic response of histidine to dietary protein changes around 10 PC%, where growth rate and body protein retention reached approximate plateaus.

The nutritional significance of the metabolism of histidine has been discussed and compared with that of leucine, alanine and serine reported previously.     

中度嗜盐菌产木聚糖酶发酵条件的研究

中度嗜盐菌在盐碱环境下生长繁殖,其产生的木聚糖酶也同样具有在盐碱环境下发挥作用的特性。本文对一株中度嗜盐菌的产木聚糖酶活性进行了初步研究。研究包括氮源、液体种子接种量、培养温度、pH值、培养时间等因素对该菌株产木聚糖酶能力的影响。结果表明,最佳培养氮源为蛋白胨;最佳产生木聚糖酶的发酵条件是液体种子接种量为6%,温度为35℃,pH值7,培养时间为4 d。     

Purification and some properties of an extracellular halophilic 5'-nucleotidase from a moderate halophile, Micrococcus varians subsp. halophilus

Abstract An extracellular 5'-nucleotidase produced by a moderate halophile, Micrococcus varians subsp. halophilus was partially purified from the culture filtrate by ethanol precipitation and Sepharose 4B hydrophobic chromatography. The 5'-nucleotidase was a novel halophilic enzyme, requiring 2 M NaCl or 2.5 M KCl and 0.1 mM Co²⁺ or 0.1 mM Mn²⁺ for maximal activity.     

嗜盐古菌几种常见胞外酶研究进展

嗜盐古菌是一类生活于极端高盐环境的化能异养型原核微生物,其所分泌的胞外酶(外泌酶)具有在高盐条件下仍能保持活性的特点,在制革工业、高盐有机废水处理和泡菜加工等腌制食品方面发挥重要用途.本文对嗜盐古菌的胞外蛋白酶、淀粉酶、酯酶等几种常见胞外酶的来源和基本酶学性质的最新研究进展进行综述,为更好地开发利用嗜盐古菌胞外酶资源提...     

Statistical optimization of medium components for extracellular protease production by an extreme haloarchaeon, Halobacterium sp. SP1(1)

Aims:  Optimization of medium components for extracellular protease production by Halobacterium sp. SP1(1) using statistical approach.
Methods and Results:  The significant factors influencing the protease production as screened by Plackett–Burman method were identified as soybean flour and FeCl₃. Response surface methodology such as central composite design was applied for further optimization studies. The concentrations of medium components for higher protease production as optimized using this approach were (g l⁻¹): NaCl, 250; KCl, 2; MgSO₄, 10; tri-Na-citrate, 1·5; soybean flour, 10 and FeCl₃, 0·16. This statistical optimization approach led to production of 69·44 ± 0·811 U ml⁻¹ of protease.
Conclusions:  Soybean flour and FeCl₃ were identified as important factors controlling the production of extracellular protease by Halobacterium sp. SP1(1). The statistical approach was found to be very effective in optimizing the medium components in manageable number of experimental runs with overall 3·9-fold increase in extracellular protease production.
Significance and Impact of the Study:  The present study is the first report on statistical optimization of medium components for production of haloarchaeal protease. The study also explored the possibility of using extracellular protease produced by Halobacterium sp. SP1(1) for various applications like antifouling coatings and fish sauce preparation using cheaper raw material.     

硅烷偶联剂的研究与应用

硅烷偶联剂是应用最广的一类偶联剂。本文阐述了其结构特征、偶联机理与使用技术,着重综述了硅烷偶联剂的应用范围与具体应用效果,最后展望了硅烷偶联剂的发展方向。