微生物文献阅读
【微生物论文】 微生物论文参考文献精选
【微生物论文】微生物论文参考文献微生物论文医学微生物学【1】【摘要】以本科预防医学专业55名学生为实施对象，进行了医学微生物学设计性实验教学的初步探讨，通过学生自己选题、查阅文献资料、设计实验方案，在教师指导下开展实验、整理与分析实验结果、撰写实验论文，有效地培养了学生的实践能力与创新能力。
【关键词】医学微生物学设计性实验创新能力随着现代科学技术的迅猛发展及知识经济时代的到来，加强学生实践能力和创新能力的培养，提高学生的综合素质，已成为目前我国高等教育教学改革的主要目标[1]。
要求医学院校在进行知识教育的同时还须加强学生实践能力和创新能力的培养，这样才能造就满足新时代需要的高素质实用型医学人才。
为此，我们在2005级本科预防医学专业的医学微生物学实验教学中进行设计性实验的初步探索，取得了良好的教学效果。
1对象与方法1.1对象选择预防医学专业本科学生作为设计性实验教学的实施对象，将医学微生物学设计性实验安排在实验教学的最后一次进行，这样学生已经系统地掌握了医学微生物学的知识，并在前期实验的基础上掌握了一定的实验技术和方法，对实验仪器设备的使用有初步了解，为完成设计性实验做好前期准备工作。
1.2方法1.2.1讲座与分组实验前2周，带教教师先给学生讲授医学科学研究的基本知识，使学生初步了解如何进行设计性实验。
学生根据自己的兴趣爱好选题，按照自由组合的原则分实验小组，每组4～6人，并推选一名学生担任实验组长。
1.2.2查阅文献资料，提出实验方案学生在组长的带领下检索、查阅文献资料与工具书，了解和掌握与实验课题有关的国内外技术状况和发展动态，并在此基础上，根据实验课题要求和实验室条件，提出具体的书面实验方案，主要包括：①实验题目;②实验目的与原理;③实验合作者;④实验动物与器材;⑤实验方法与步骤;⑥观察指标;⑦注意事项;⑧参考文献;⑨实验计划进度等。
1.2.3实验方案的讨论与确定教师认真审查学生拟定的实验方案，组织学生对实验方案的可行性进行讨论。
微生物英文文献及翻译—翻译
A/O法活性污泥中氨氧化菌群落的动态与分布摘要：我们研究了在厌氧—好氧序批式反应器（SBR）中氨氧化菌群落（AOB）和亚硝酸盐氧化菌群落（NOB）的结构活性和分布。
在研究过程中，分子生物技术和微型技术被用于识别和鉴定这些微生物。
污泥微粒中的氨氧化菌群落结构大体上与初始的接种污泥中的结构不同。
与颗粒形成一起，由于过程条件中生物选择的压力，AOB的多样性下降了。
DGGE测序表明，亚硝化菌依然存在，这是因为它们能迅速的适应固定以对抗洗涤行为。
DGGE更进一步的分析揭露了较大的微粒对更多的AOB种类在反应器中的生存有好处。
在SBR反应器中有很多大小不一的微粒共存，颗粒的直径影响这AOB和NOB的分布。
中小微粒（直径<0.6mm）不能限制氧在所有污泥空间的传输。
大颗粒（直径>0.9mm）可以使含氧量降低从而限制NOB的生长。
所有这些研究提供了未来对AOB微粒系统机制可能性研究的支持。
关键词：氨氧化菌（AOB），污泥微粒，菌落发展，微粒大小，硝化菌分布，发育多样性1.简介在浓度足够高的条件下，氨在水环境中对水生生物有毒，并且对富营养化有贡献。
因此，废水中氨的生物降解和去除是废水处理工程的基本功能。
硝化反应，将氨通过硝化转化为硝酸盐，是去除氨的一个重要途径。
这是分两步组成的，由氨氧化和亚硝酸盐氧化细菌完成。
好氧氨氧化一般是第一步，硝化反应的限制步骤：然而，这是废水中氨去除的本质。
对16S rRNA的对比分析显示，大多数活性污泥里的氨氧化菌系统的跟ß-变形菌有关联。
然而，一系列的研究表明，在氨氧化菌的不同代和不同系有生理和生态区别，而且环境因素例如处理常量，溶解氧，盐度，pH，自由氨例子浓度会影响氨氧化菌的种类。
因此，废水处理中氨氧化菌的生理活动和平衡对废水处理系统的设计和运行是至关重要的。
由于这个原因，对氨氧化菌生态和微生物学更深一层的了解对加强处理效果是必须的。
当今，有几个进阶技术在废水生物处理系统中被用作鉴别、刻画微生物种类的有价值的工具。
微生物英文文献及翻译—原文
微生物英文文献及翻译—原文本期为微生物学的第二讲，主要讨论炭疽和蛔虫病这两种既往常见而当今社会较为罕见的疾病。
炭疽是由炭疽杆菌所致的一种人畜共患的急性传染病。
人因接触病畜及其产品及食用病畜的肉类而发生感染。
临床上主要表现为皮肤坏死、溃疡、焦痂和周围组织广泛水肿及毒血症症状；似蚓蛔线虫简称蛔虫，是人体内最常见的寄生虫之一。
成虫寄生于小肠，可引起蛔虫病。
其幼虫能在人体内移行，引起内脏幼虫移行症。
案例分析Case 1：A local craftsman who makes garments from the hides of goats visits his physician because over the past few days he has developed several black lesions on his hands and arms. The lesions are not painful, but he is alarmed by their appearance. He is afebrile and his physical examination is unremarkable.案例1：一名使用鹿皮做皮衣的当地木匠来就医，主诉过去几天中手掌和手臂上出现几个黑色皮肤损害。
皮损无痛，但是外观较为骇人。
患者无发热，体检无异常发现。
1. What is the most likely diagnosis?Cutaneous anthrax, caused by Bacillus anthracis. The skin lesions are painless and dark or charred ulcerations known as black eschar. It is classically transmitted by contact with thehide of a goat at the site of a minor open wound.皮肤炭疽：由炭疽杆菌引起，皮损通常无痛、黑色或称为焦痂样溃疡。
微生物英文文献
Results
二、分子鉴定
(1) Pca-QS-0-1, Pch-QS-0-3, and Pe-QS-0-1;
Results
二、分子鉴定
(5) Pv-QS-0-1;
Results
Two new ITS-5.8S rDNA sequence types
(1) Cl-QS-0-1 and Cl-QS-0-2 are two new anamorph species in the genus Tulasnella. (2) Pv-QS-0-1 did not show high homology with high Sequence
成 苗
碳 源 种子发芽
Many fungi isolated from mycorrhizal orchid roots have been classified as Rhizoctonia or Rhizoctonia-like
fungi.
Plant materials
B. Why 27种is Rhizoctonia-like Fungi？
Molecular characterization
Homogenizing
PCR Purifing Sequencing
样品均匀 扩增
纯化 基因测序
Sequence analysis
Results
一、形态学
(1) Pca-QS-0-1, Pch-QS-0-3, and Pe-QS-0-1; (2) D1-KT-TC-1 and C3-DT-TC-2; (3) Pv-QS-0-2 and Df-QS-3-1;
Orchids rely on the infection of Rhizoctonia-like fungi
微生物英文文献及翻译—翻译
A/O法活性污泥中氨氧化菌群落的动态与分布摘要：我们研究了在厌氧—好氧序批式反应器（SBR）中氨氧化菌群落（AOB）和亚硝酸盐氧化菌群落（NOB）的结构活性和分布。
在研究过程中，分子生物技术和微型技术被用于识别和鉴定这些微生物。
污泥微粒中的氨氧化菌群落结构大体上与初始的接种污泥中的结构不同。
与颗粒形成一起，由于过程条件中生物选择的压力，AOB的多样性下降了。
DGGE测序表明，亚硝化菌依然存在，这是因为它们能迅速的适应固定以对抗洗涤行为。
DGGE更进一步的分析揭露了较大的微粒对更多的AOB种类在反应器中的生存有好处。
在SBR反应器中有很多大小不一的微粒共存，颗粒的直径影响这AOB和NOB的分布。
中小微粒（直径<0.6mm）不能限制氧在所有污泥空间的传输。
大颗粒（直径>0.9mm）可以使含氧量降低从而限制NOB的生长。
所有这些研究提供了未来对AOB微粒系统机制可能性研究的支持。
关键词：氨氧化菌（AOB），污泥微粒，菌落发展，微粒大小，硝化菌分布，发育多样性•简介在浓度足够高的条件下，氨在水环境中对水生生物有毒，并且对富营养化有贡献。
因此，废水中氨的生物降解和去除是废水处理工程的基本功能。
硝化反应，将氨通过硝化转化为硝酸盐，是去除氨的一个重要途径。
这是分两步组成的，由氨氧化和亚硝酸盐氧化细菌完成。
好氧氨氧化一般是第一步，硝化反应的限制步骤：然而，这是废水中氨去除的本质。
对16S rRNA的对比分析显示，大多数活性污泥里的氨氧化菌系统的跟ß-变形菌有关联。
然而，一系列的研究表明，在氨氧化菌的不同代和不同系有生理和生态区别，而且环境因素例如处理常量，溶解氧，盐度，pH，自由氨例子浓度会影响氨氧化菌的种类。
因此，废水处理中氨氧化菌的生理活动和平衡对废水处理系统的设计和运行是至关重要的。
由于这个原因，对氨氧化菌生态和微生物学更深一层的了解对加强处理效果是必须的。
当今，有几个进阶技术在废水生物处理系统中被用作鉴别、刻画微生物种类的有价值的工具。
食品微生物参考文献
食品微生物参考文献毕业论文中的参考文献在一般状况下需要笔者将论文之中的学术资料、论文研究文献、注释文献等等诸多资料进行集中展示与整合，进而集中地展现在论文形态之中，下面是店铺整理推荐的一篇关于食品微生物参考文献，欢迎阅读参考。
关于食品微生物文献1 黄丹，殷文政.呼和浩特地区乳中金黄色葡萄球菌的分离鉴定及药敏性试验研究[J].农产品加工，2007 , (12) : 72 - 742 刘冬香.动物性食品源金黄色葡萄球菌的耐药分析及blaZ、mecA和nuc基因的多重PCR [D].内蒙古农业大学，20093 东秀珠，.蔡妙英?常见细菌系统鉴定手册[M].北京：科学出版社，2001: 246-2554 何庆国，贾英民.食品微生物学[M].北京：中国农业大学出版社，2002: 381-3825 刘秀梅.试论国内外食品安全保障体系[C].6 双金，嘎尔迪等.奶牛隐性乳腺炎的发生规律及其致病菌的分离鉴别与药物敏感性试验[门.内蒙古农业大学学报，2001，22(1): 18-237 张中文.北京地区奶牛乳腺炎病原菌的分离鉴定与药敏试验[J].北京农学院学2002,17(4): 44-478 史冬艳.奶牛乳房炎金黄色葡萄球菌耐药性及以黏附素为靶位的疫苗的基础研究[D].内蒙古农业大学，20109 张善瑞.奶牛乳腺炎主要病原茵快速诊断及金葡菌a-溶血素的原核表达[D].山东农业大学，2007’ 233-23510 Walev I，Weller U，Strauch S，et al. Selective killing of human monocytes and cytokine release provoked by sphingomyelinase(beta-toxin)of Staphylococcus aurous[J]. Infect Immune, 1996，64(8): 2974-297911王蟲.金黄色葡萄球菌Panton-Valentine杀白细胞素的研究进展[J].国外医药抗生素分册，2006，27 ( 6 ): 269-27112 Litton M J，Dohlsten M ,Hansson J，et.al. Tumor the ropy with an antibody-targeted superantigen generate a dichotomy between local an systemic immune responses [J]. American Journal of Pathology, 1997, 150(5): 1670-161713 Brakstad O.QAasbakk K”Maeland J.A.,1992, Detection of Staphylococcus aureus by polymerase chain reaction amplification of the nuc geneJ.Clin,Microbiol.30 :1654-166014 Chesneau，0.，Allignet,J .and el Solh，N.1993，Thermonuclease gene as a target nucleotide sequence for specific recognition of Staphylococcus aureus.Mol.Cell Probes.7(4) :301-31015 Levy S B. The antibiotic paradox : how miracle drugs are destroying the miracle[M].New York, Plenum, 1992,ISBN 0-306-44331-7 37:32-3816 Jevons M P. “ Cellbenin \"-resistant staphylococci [J] .BMJ, 1961,1:124-12517 Van Duijkeren,Wolfhagen E，Boxe M J，et al.Human-to-dog transmission of methicillin 一resistant Staphylococcus aureus[J].Ermerg Infect,2004,10,2235-223718 Leonard F C，Markey B K. Meticillin-resistant Staphylococcus aureus in animals: a review[J].Vet, 2008,175:27-3619 Farmer T H, Gilbart J, Elson S W. Biochermical basis of mupirocin resistance in strains of Staphylococcus aureus[J]. Antimicrob Chermother, 1992,30:587-59620 丁兆凤.奶牛乳房炎金黄色葡萄球菌红霉素耐药机制分析[D].黑龙江八一农垦大学，2010, 1-221 Higgins C F, Hyde S C, Mimmack M M, et al. Binding protein-dependent transport systems [J]. Bioenerg Biomennbr,1990,22:571-59222 Rose S D. Application of a novel microarraying system in genomics research and drug discovery[J]. Association Laboratory Automation，1998,3:53—5623 Allignet J, Aubert S, Morvan A, et al. Distribution of genes encoding resistance to streptogramin A and related compounds among staphylococci resistant to these antibiotics[J].Antimicrob Agents Chermother, 1996, 40:2523-252824 Eltringham I. Mupirocin resistance and methicillin-resistant Staphylococcus aureus(MRSA) [J],Hosp. Infect, 1997,35:1-825牛志强，郑敏.P-内酰胺类抗生素应用知识[J].中国动物保健，2009，6: 63-66食品微生物参考文献毕业论文中的参考文献在一般状况下需要笔者将论文之中的学术资料、论文研究文献、注释文献等等诸多资料进行集中展示与整合，进而集中地展现在论文形态之中，下面是店铺整理推荐的一篇关于食品微生物参考文献，欢迎阅读参考。
生物学微生物论文
生物学微生物论文生物学微生物论文学生物专业的同学们，你们的毕业论文准备好了吗?毕业论文题目是什么呢?以下是关于生物学微生物论文，欢迎阅读!生物学微生物论文【1】生物医学中核酸适体应用分析摘要:核酸适体是一种经配体指数富集系统进化技术筛选而出的一种可以特异性结合的离子和分子，核酸适体在生物医学领域有着良好的发展前景。
主要针对核酸适体在生物医学中的应用进行分析。
关键词:核酸适体;生物医学;应用1基于核酸适体的生物医学诊断1.1生物大分子检测随着人类基因组计划的完成，研究蛋白质等生物大分子的具体跟踪检测高灵敏分析方法已经是目前基因组学的研究热点和重点。
原来的蛋白质检测一般是根据抗原/抗体免疫分析的方式来进行检测，一般分析出来的数据都会受到抗体性质的干扰。
而核酸适体能够与蛋白质进行特异性结合，在不同温度、不同盐浓度络合剂条件下能够进行特异性变性与复性研究，所以在蛋白质分析检测上的使用越来越受到各方面重视。
运用核酸适体能够通过GIC方法实施扩增的特点，增强酶联核酸适体诊断方法的检测精确度，把两种不一样的核酸适体组合到蛋白或蛋白复合体两个相近的结合位置上，两种核酸适体的游离末端通过互补碱基链接起来，最终根据GIC方式实施实时扩增。
与传统的检测方法相比较，该种新型检测方式非常明显地应用了核酸适体在发展各种可取代抗体的蛋白靶的功能，在测定体内蛋白质含量和研究蛋白质的功能以及对疾病的早期诊断等方面拥有非常大的使用价值。
1.2肿瘤细胞鉴别分析从分子水平实现早期癌细胞的准确检测具有非常重要的意义，因此设计和发展特异性分子探针成为癌细胞早期检测的关键因素。
研究显示，将前列腺专一性膜抗原(GFBE)的核酸适体连接到具有近红外光性能的量子点上，可以特异性地检测前列腺癌细胞，为核酸适体应用于活细胞及生物体内的分子检测提供了新思路。
在癌症早期检测中，从病人血液或唾液等收集到的恶性肿瘤细胞含量通常较低，所以发展一种从低含量体液中聚集并检测肿瘤细胞的方案成为目前癌症早期诊断的核心，运用先进的双功能纳米粒子作用于白血病细胞的加速富集与检测的速度。
微生物技术 文献综述
微生物修复石油污染的研究概况湖州师范学院生命科学蒋立勋摘要：对于现如今石油的大量的开采，石油泄漏的状况发生的几率持续升高，近期的几个的漏油事故，对于它们的后续处理非常关键，特别是如何恢复原先的生态环境，利用微生物进行处理不失为一种环保的方式。
文章较全面地介绍了环境中降解石油的微生物、石油污染土壤的微生物修复技术以及影响石油污染土壤微生物修复的因素。
关键词：石油污染，微生物修复石油是不可再生资源，也是人类宝贵的能源和重要的化工原料，目前国际油品市场原油价格的持续上涨，将直接影响着我国经济的可持续发展［1］。
但同时，我国每年还有大量的原油及其加工品流入环境，这不但浪费了宝贵的资源，而且对生态环境造成了污染［2］。
石油物质进入土壤后，会引起土壤理化特性发生变化，能够改变土壤有机质的组成和结构，对作物生长发育也有不利的影响［3］。
同时石油通过生长于该土壤中的植物及其产品，以食物链方式直接影响到人类的身体健康［4］。
在最初的石油污染治理工艺中，物理和化学方式处理是最主要的技术，且已研究得比较成熟。
自20 世纪70 年代以来，随着生物修复技术的发展，微生物处理技术在石油污染治理方面逐渐成为核心技术［5］。
为了全面了解石油污染土壤微生物修复研究现状，从而指导现阶段的研究工作。
笔者针对近几年国内外的应用微生物修复技术治理石油污染土壤的最新研究成果与应用状况进行了初步归纳，并对未来的发展进行了展望。
1 环境中降解石油的微生物动物、植物、微生物都具有降解污染物的能力，但微生物在污染物降解中的作用最大；这是由于微生物具有种类多、分布广、个体小、繁殖快、比表面积大、容易变异的特点所决定的。
微生物的降解酶体系具有氧化还原、脱羧、脱氨、水解、脱水等各种化学作用能力，所以对能量的利用比高等生物体更加有效；微生物高速度的繁殖特性和遗传变异性使它的酶体系能够以最快的速度适应外界环境的变化，从而显示出其在环境治理上的高效性和多样性。
微生物文献综述附参考文献
乳酸菌在生产中的应用及其鉴定方法摘要：乳酸菌指发酵糖类主要产物为乳酸的一类无芽孢、革兰氏染色阳性细菌的总称。
其在食品工业的应用具有悠久的历史,也是一种宝贵的微生物资源, 和我们的健康息息相关。
本文介绍了乳酸菌在实际生产中的应用,以及目前研究中发现适用于乳酸菌的鉴定技术.关键词：乳酸菌应用鉴定Abstract：Lactic acid bacteria refer to a class of non — spore, gram positive bacteria, which is the main product of lactic acid. It have been applied in food industryfor a long time and are valuable resource of microorganisms, which closelyrelated to our health。
The application of lactic acid bacteria in the practicalproduction and the identification technology of the present research wereintroduced。
Keywords：Lactic acid bacteria Application identification1。
前言乳酸菌指发酵糖类主要产物为乳酸的一类无芽孢、革兰氏染色阳性细菌的总称,是一个广义范畴的概念而非正式的细菌分类学名称。
乳酸菌可以分成18个属，共有200多种。
乳酸菌的功能主要有: 改善人体肠道功能，恢复人体肠道内菌群平衡，增强人体免疫能力，抑制腐败菌的生长，降低胆固醇, 抗氧化, 抗高血压，抗肿瘤，保藏食品，改善食品风味等。
人们要利用乳酸菌，就需要了解它们的生物学特性，因此对乳酸菌进行快速、准确的分类与鉴定在微生物学和食品科学的研究中是必需的。
微生物学读书笔记
微生物学读书笔记微生物学读书笔记【篇一：微生物学文献读书笔记】微生物学文献读后感一、文章题目a novel approach for assessing the susceptibility of escherichia coli to antibiotics （评估大肠杆菌对抗生素易感性的一种新方法）二、文章概要escherichia coli cvcc249 在不同抗生素浓度下的动态增长过程的分析结果表明，不能获得理想的最终结果的原因是用ast法不能完全确定药物浓度和细菌数量之比以及药物浓度和作用时间的综合效应。
基于一系列浓度梯度的庆大霉素处理一定时间细菌的增长过程的分析，以及根据向前差分法，一种ast新方法被提了出来。
三、研究背景1、ast（药敏试验）是临床微生物学实验室最重要的任务之一，它通常定性在mic（最低抑制浓度）和mbc（最低杀菌浓度），这是由不同的杀菌方法和纸片扩散确定的。
从ast获得的参数通常用来表明抗性反应或细菌对抗生素的敏感性，利用这些结果提供合理用药指导。
2、然而，由于ast的结果容易受到许多不确定因素的影响，使得耐药性和敏感性之间的断点变得相当难以区分。
许多临床研究组织为ast的标准化方法作了巨大的努力。
美国临床试验标准研究所1971年提出了clsi的标准化方法，还有后来英国抗菌化疗协会提出bsac 法，欧洲药敏测试委员会提出eucast法等。
尽管标准在逐渐完善和提高，但前面的路还着实很远。
3、为了解决这个问题，该实验室设计了许多实验，改善ast方法。
根据fibonacci 序列分析，他们用细菌浊度的rc作为目标函数，提出了ast新方法。
这个方法有望发展成为药效学的一种常用方法。
四、研究材料1、从鸡中分离出来的致病性大肠杆菌e. coli cvcc2492、标准质量控制菌株 e. coli 25922五、研究方法1、用增长序列浊度的rc值描述抗生素的抑制率细菌细胞分裂的发生是一个随机过程，在任何时候细胞分裂都会有一定的比例。
微生物英文文献及翻译—原文
Dynamic and distribution of ammonia-oxidizing bacteria communities during sludge granulation in an anaerobic e aerobic sequencing batch reactorZhang Bin a ,b ,Chen Zhe a ,b ,Qiu Zhigang a ,b ,Jin Min a ,b ,Chen Zhiqiang a ,b ,Chen Zhaoli a ,b ,Li Junwen a ,b ,Wang Xuan c ,*,Wang Jingfeng a ,b ,**aInstitute of Hygiene and Environmental Medicine,Academy of Military Medical Sciences,Tianjin 300050,PR China bTianjin Key Laboratory of Risk Assessment and Control for Environment and Food Safety,Tianjin 300050,PR China cTianjin Key Laboratory of Hollow Fiber Membrane Material and Membrane Process,Institute of Biological and Chemical Engineering,Tianjin Polytechnical University,Tianjin 300160,PR Chinaa r t i c l e i n f oArticle history:Received 30June 2011Received in revised form 10September 2011Accepted 10September 2011Available online xxx Keywords:Ammonia-oxidizing bacteria Granular sludgeCommunity development Granule sizeNitrifying bacteria distribution Phylogenetic diversitya b s t r a c tThe structure dynamic of ammonia-oxidizing bacteria (AOB)community and the distribution of AOB and nitrite-oxidizing bacteria (NOB)in granular sludge from an anaerobic e aerobic sequencing batch reactor (SBR)were investigated.A combination of process studies,molecular biotechniques and microscale techniques were employed to identify and characterize these organisms.The AOB community structure in granules was substantially different from that of the initial pattern of the inoculants sludge.Along with granules formation,the AOB diversity declined due to the selection pressure imposed by process conditions.Denaturing gradient gel electrophoresis (DGGE)and sequencing results demonstrated that most of Nitrosomonas in the inoculating sludge were remained because of their ability to rapidly adapt to the settling e washing out action.Furthermore,DGGE analysis revealed that larger granules benefit more AOB species surviving in the reactor.In the SBR were various size granules coexisted,granule diameter affected the distribution range of AOB and NOB.Small and medium granules (d <0.6mm)cannot restrict oxygen mass transfer in all spaces of the rger granules (d >0.9mm)can result in smaller aerobic volume fraction and inhibition of NOB growth.All these observations provide support to future studies on the mechanisms responsible for the AOB in granules systems.ª2011Elsevier Ltd.All rights reserved.1.IntroductionAt sufficiently high levels,ammonia in aquatic environments can be toxic to aquatic life and can contribute to eutrophica-tion.Accordingly,biodegradation and elimination of ammonia in wastewater are the primary functions of thewastewater treatment process.Nitrification,the conversion of ammonia to nitrate via nitrite,is an important way to remove ammonia nitrogen.It is a two-step process catalyzed by ammonia-oxidizing and nitrite-oxidizing bacteria (AOB and NOB).Aerobic ammonia-oxidation is often the first,rate-limiting step of nitrification;however,it is essential for the*Corresponding author .**Corresponding author.Institute of Hygiene and Environmental Medicine,Academy of Military Medical Sciences,Tianjin 300050,PR China.Tel.:+862284655498;fax:+862223328809.E-mail addresses:wangxuan0116@ (W.Xuan),jingfengwang@ (W.Jingfeng).Available online atjournal homepage:/locate/watresw a t e r r e s e a r c h x x x (2011)1e 100043-1354/$e see front matter ª2011Elsevier Ltd.All rights reserved.doi:10.1016/j.watres.2011.09.026removal of ammonia from the wastewater(Prosser and Nicol, 2008).Comparative analyses of16S rRNA sequences have revealed that most AOB in activated sludge are phylogeneti-cally closely related to the clade of b-Proteobacteria (Kowalchuk and Stephen,2001).However,a number of studies have suggested that there are physiological and ecological differences between different AOB genera and lineages,and that environmental factors such as process parameter,dis-solved oxygen,salinity,pH,and concentrations of free ammonia can impact certain species of AOB(Erguder et al., 2008;Kim et al.,2006;Koops and Pommerening-Ro¨ser,2001; Kowalchuk and Stephen,2001;Shi et al.,2010).Therefore, the physiological activity and abundance of AOB in waste-water processing is critical in the design and operation of waste treatment systems.For this reason,a better under-standing of the ecology and microbiology of AOB in waste-water treatment systems is necessary to enhance treatment performance.Recently,several developed techniques have served as valuable tools for the characterization of microbial diversity in biological wastewater treatment systems(Li et al., 2008;Yin and Xu,2009).Currently,the application of molec-ular biotechniques can provide clarification of the ammonia-oxidizing community in detail(Haseborg et al.,2010;Tawan et al.,2005;Vlaeminck et al.,2010).In recent years,the aerobic granular sludge process has become an attractive alternative to conventional processes for wastewater treatment mainly due to its cell immobilization strategy(de Bruin et al.,2004;Liu et al.,2009;Schwarzenbeck et al.,2005;Schwarzenbeck et al.,2004a,b;Xavier et al.,2007). Granules have a more tightly compact structure(Li et al.,2008; Liu and Tay,2008;Wang et al.,2004)and rapid settling velocity (Kong et al.,2009;Lemaire et al.,2008).Therefore,granular sludge systems have a higher mixed liquid suspended sludge (MLSS)concentration and longer solid retention times(SRT) than conventional activated sludge systems.Longer SRT can provide enough time for the growth of organisms that require a long generation time(e.g.,AOB).Some studies have indicated that nitrifying granules can be cultivated with ammonia-rich inorganic wastewater and the diameter of granules was small (Shi et al.,2010;Tsuneda et al.,2003).Other researchers reported that larger granules have been developed with the synthetic organic wastewater in sequencing batch reactors(SBRs)(Li et al., 2008;Liu and Tay,2008).The diverse populations of microor-ganisms that coexist in granules remove the chemical oxygen demand(COD),nitrogen and phosphate(de Kreuk et al.,2005). However,for larger granules with a particle diameter greater than0.6mm,an outer aerobic shell and an inner anaerobic zone coexist because of restricted oxygen diffusion to the granule core.These properties of granular sludge suggest that the inner environment of granules is unfavorable to AOB growth.Some research has shown that particle size and density induced the different distribution and dominance of AOB,NOB and anam-mox(Winkler et al.,2011b).Although a number of studies have been conducted to assess the ecology and microbiology of AOB in wastewater treatment systems,the information on the dynamics,distribution,and quantification of AOB communities during sludge granulation is still limited up to now.To address these concerns,the main objective of the present work was to investigate the population dynamics of AOB communities during the development of seedingflocs into granules,and the distribution of AOB and NOB in different size granules from an anaerobic e aerobic SBR.A combination of process studies,molecular biotechniques and microscale techniques were employed to identify and char-acterize these organisms.Based on these approaches,we demonstrate the differences in both AOB community evolu-tion and composition of theflocs and granules co-existing in the SBR and further elucidate the relationship between distribution of nitrifying bacteria and granule size.It is ex-pected that the work would be useful to better understand the mechanisms responsible for the AOB in granules and apply them for optimal control and management strategies of granulation systems.2.Material and methods2.1.Reactor set-up and operationThe granules were cultivated in a lab-scale SBR with an effective volume of4L.The effective diameter and height of the reactor was10cm and51cm,respectively.The hydraulic retention time was set at8h.Activated sludge from a full-scale sewage treat-ment plant(Jizhuangzi Sewage Treatment Works,Tianjin, China)was used as the seed sludge for the reactor at an initial sludge concentration of3876mg LÀ1in MLSS.The reactor was operated on6-h cycles,consisting of2-min influent feeding,90-min anaerobic phase(mixing),240-min aeration phase and5-min effluent discharge periods.The sludge settling time was reduced gradually from10to5min after80SBR cycles in20days, and only particles with a settling velocity higher than4.5m hÀ1 were retained in the reactor.The composition of the influent media were NaAc(450mg LÀ1),NH4Cl(100mg LÀ1),(NH4)2SO4 (10mg LÀ1),KH2PO4(20mg LÀ1),MgSO4$7H2O(50mg LÀ1),KCl (20mg LÀ1),CaCl2(20mg LÀ1),FeSO4$7H2O(1mg LÀ1),pH7.0e7.5, and0.1mL LÀ1trace element solution(Li et al.,2007).Analytical methods-The total organic carbon(TOC),NHþ4e N, NOÀ2e N,NOÀ3e N,total nitrogen(TN),total phosphate(TP) concentration,mixed liquid suspended solids(MLSS) concentration,and sludge volume index at10min(SVI10)were measured regularly according to the standard methods (APHA-AWWA-WEF,2005).Sludge size distribution was determined by the sieving method(Laguna et al.,1999).Screening was performed with four stainless steel sieves of5cm diameter having respective mesh openings of0.9,0.6,0.45,and0.2mm.A100mL volume of sludge from the reactor was sampled with a calibrated cylinder and then deposited on the0.9mm mesh sieve.The sample was subsequently washed with distilled water and particles less than0.9mm in diameter passed through this sieve to the sieves with smaller openings.The washing procedure was repeated several times to separate the gran-ules.The granules collected on the different screens were recovered by backwashing with distilled water.Each fraction was collected in a different beaker andfiltered on quantitative filter paper to determine the total suspended solid(TSS).Once the amount of total suspended solid(TSS)retained on each sieve was acquired,it was reasonable to determine for each class of size(<0.2,[0.2e0.45],[0.45e0.6],[0.6e0.9],>0.9mm) the percentage of the total weight that they represent.w a t e r r e s e a r c h x x x(2011)1e10 22.2.DNA extraction and nested PCR e DGGEThe sludge from approximately8mg of MLSS was transferred into a1.5-mL Eppendorf tube and then centrifuged at14,000g for10min.The supernatant was removed,and the pellet was added to1mL of sodium phosphate buffer solution and aseptically mixed with a sterilized pestle in order to detach granules.Genomic DNA was extracted from the pellets using E.Z.N.A.äSoil DNA kit(D5625-01,Omega Bio-tek Inc.,USA).To amplify ammonia-oxidizer specific16S rRNA for dena-turing gradient gel electrophoresis(DGGE),a nested PCR approach was performed as described previously(Zhang et al., 2010).30m l of nested PCR amplicons(with5m l6Âloading buffer)were loaded and separated by DGGE on polyacrylamide gels(8%,37.5:1acrylamide e bisacrylamide)with a linear gradient of35%e55%denaturant(100%denaturant¼7M urea plus40%formamide).The gel was run for6.5h at140V in 1ÂTAE buffer(40mM Tris-acetate,20mM sodium acetate, 1mM Na2EDTA,pH7.4)maintained at60 C(DCodeäUniversal Mutation Detection System,Bio-Rad,Hercules,CA, USA).After electrophoresis,silver-staining and development of the gels were performed as described by Sanguinetti et al. (1994).These were followed by air-drying and scanning with a gel imaging analysis system(Image Quant350,GE Inc.,USA). The gel images were analyzed with the software Quantity One,version4.31(Bio-rad).Dice index(Cs)of pair wise community similarity was calculated to evaluate the similarity of the AOB community among DGGE lanes(LaPara et al.,2002).This index ranges from0%(no common band)to100%(identical band patterns) with the assistance of Quantity One.The Shannon diversity index(H)was used to measure the microbial diversity that takes into account the richness and proportion of each species in a population.H was calculatedusing the following equation:H¼ÀPn iNlogn iN,where n i/Nis the proportion of community made up by species i(bright-ness of the band i/total brightness of all bands in the lane).Dendrograms relating band pattern similarities were automatically calculated without band weighting(consider-ation of band density)by the unweighted pair group method with arithmetic mean(UPGMA)algorithms in the Quantity One software.Prominent DGGE bands were excised and dissolved in30m L Milli-Q water overnight,at4 C.DNA was recovered from the gel by freeze e thawing thrice.Cloning and sequencing of the target DNA fragments were conducted following the estab-lished method(Zhang et al.,2010).2.3.Distribution of nitrifying bacteriaThree classes of size([0.2e0.45],[0.45e0.6],>0.9mm)were chosen on day180for FISH analysis in order to investigate the spatial distribution characteristics of AOB and NOB in granules.2mg sludge samples werefixed in4%para-formaldehyde solution for16e24h at4 C and then washed twice with sodium phosphate buffer;the samples were dehydrated in50%,80%and100%ethanol for10min each. Ethanol in the granules was then completely replaced by xylene by serial immersion in ethanol-xylene solutions of3:1, 1:1,and1:3by volume andfinally in100%xylene,for10min periods at room temperature.Subsequently,the granules were embedded in paraffin(m.p.56e58 C)by serial immer-sion in1:1xylene-paraffin for30min at60 C,followed by 100%paraffin.After solidification in paraffin,8-m m-thick sections were prepared and placed on gelatin-coated micro-scopic slides.Paraffin was removed by immersing the slide in xylene and ethanol for30min each,followed by air-drying of the slides.The three oligonucleotide probes were used for hybridiza-tion(Downing and Nerenberg,2008):FITC-labeled Nso190, which targets the majority of AOB;TRITC-labeled NIT3,which targets Nitrobacter sp.;TRITC-labeled NSR1156,which targets Nitrospira sp.All probe sequences,their hybridization condi-tions,and washing conditions are given in Table1.Oligonu-cleotides were synthesized andfluorescently labeled with fluorochomes by Takara,Inc.(Dalian,China).Hybridizations were performed at46 C for2h with a hybridization buffer(0.9M NaCl,formamide at the percentage shown in Table1,20mM Tris/HCl,pH8.0,0.01% SDS)containing each labeled probe(5ng m LÀ1).After hybrid-ization,unbound oligonucleotides were removed by a strin-gent washing step at48 C for15min in washing buffer containing the same components as the hybridization buffer except for the probes.For detection of all DNA,4,6-diamidino-2-phenylindole (DAPI)was diluted with methanol to afinal concentration of1ng m LÀ1.Cover the slides with DAPI e methanol and incubate for15min at37 C.The slides were subsequently washed once with methanol,rinsed briefly with ddH2O and immediately air-dried.Vectashield(Vector Laboratories)was used to prevent photo bleaching.The hybridization images were captured using a confocal laser scanning microscope (CLSM,Zeiss710).A total of10images were captured for each probe at each class of size.The representative images were selected andfinal image evaluation was done in Adobe PhotoShop.w a t e r r e s e a r c h x x x(2011)1e1033.Results3.1.SBR performance and granule characteristicsDuring the startup period,the reactor removed TOC and NH 4þ-N efficiently.98%of NH 4þ-N and 100%of TOC were removed from the influent by day 3and day 5respectively (Figs.S2,S3,Supporting information ).Removal of TN and TP were lower during this period (Figs.S3,S4,Supporting information ),though the removal of TP gradually improved to 100%removal by day 33(Fig.S4,Supporting information ).To determine the sludge volume index of granular sludge,a settling time of 10min was chosen instead of 30min,because granular sludge has a similar SVI after 60min and after 5min of settling (Schwarzenbeck et al.,2004b ).The SVI 10of the inoculating sludge was 108.2mL g À1.The changing patterns of MLSS and SVI 10in the continuous operation of the SBR are illustrated in Fig.1.The sludge settleability increased markedly during the set-up period.Fig.2reflects the slow andgradual process of sludge granulation,i.e.,from flocculentsludge to granules.3.2.DGGE analysis:AOB communities structure changes during sludge granulationThe results of nested PCR were shown in Fig.S1.The well-resolved DGGE bands were obtained at the representative points throughout the GSBR operation and the patterns revealed that the structure of the AOB communities was dynamic during sludge granulation and stabilization (Fig.3).The community structure at the end of experiment was different from that of the initial pattern of the seed sludge.The AOB communities on day 1showed 40%similarity only to that at the end of the GSBR operation (Table S1,Supporting information ),indicating the considerable difference of AOB communities structures between inoculated sludge and granular sludge.Biodiversity based on the DGGE patterns was analyzed by calculating the Shannon diversity index H as204060801001201401254159738494104115125135147160172188Time (d)S V I 10 (m L .g -1)10002000300040005000600070008000900010000M L S S (m g .L -1)Fig.1e Change in biomass content and SVI 10during whole operation.SVI,sludge volume index;MLSS,mixed liquid suspendedsolids.Fig.2e Variation in granule size distribution in the sludge during operation.d,particle diameter;TSS,total suspended solids.w a t e r r e s e a r c h x x x (2011)1e 104shown in Fig.S5.In the phase of sludge inoculation (before day 38),H decreased remarkably (from 0.94to 0.75)due to the absence of some species in the reactor.Though several dominant species (bands2,7,10,11)in the inoculating sludge were preserved,many bands disappeared or weakened (bands 3,4,6,8,13,14,15).After day 45,the diversity index tended to be stable and showed small fluctuation (from 0.72to 0.82).Banding pattern similarity was analyzed by applying UPGMA (Fig.4)algorithms.The UPGMA analysis showed three groups with intragroup similarity at approximately 67%e 78%and intergroup similarity at 44e 62%.Generally,the clustering followed the time course;and the algorithms showed a closer clustering of groups II and III.In the analysis,group I was associated with sludge inoculation and washout,group IIwithFig.3e DGGE profile of the AOB communities in the SBR during the sludge granulation process (lane labels along the top show the sampling time (days)from startup of the bioreactor).The major bands were labeled with the numbers (bands 1e15).Fig.4e UPGMA analysis dendrograms of AOB community DGGE banding patterns,showing schematics of banding patterns.Roman numerals indicate major clusters.w a t e r r e s e a r c h x x x (2011)1e 105startup sludge granulation and decreasing SVI 10,and group III with a stable system and excellent biomass settleability.In Fig.3,the locations of the predominant bands were excised from the gel.DNA in these bands were reamplified,cloned and sequenced.The comparative analysis of these partial 16S rRNA sequences (Table 2and Fig.S6)revealed the phylogenetic affiliation of 13sequences retrieved.The majority of the bacteria in seed sludge grouped with members of Nitrosomonas and Nitrosospira .Along with sludge granula-tion,most of Nitrosomonas (Bands 2,5,7,9,10,11)were remained or eventually became dominant in GSBR;however,all of Nitrosospira (Bands 6,13,15)were gradually eliminated from the reactor.3.3.Distribution of AOB and NOB in different sized granulesFISH was performed on the granule sections mainly to deter-mine the location of AOB and NOB within the different size classes of granules,and the images were not further analyzed for quantification of cell counts.As shown in Fig.6,in small granules (0.2mm <d <0.45mm),AOB located mainly in the outer part of granular space,whereas NOB were detected only in the core of granules.In medium granules (0.45mm <d <0.6mm),AOB distributed evenly throughout the whole granular space,whereas NOB still existed in the inner part.In the larger granules (d >0.9mm),AOB and NOB were mostly located in the surface area of the granules,and moreover,NOB became rare.4.Discussion4.1.Relationship between granule formation and reactor performanceAfter day 32,the SVI 10stabilized at 20e 35mL g À1,which is very low compared to the values measured for activated sludge (100e 150mL g À1).However,the size distribution of the granules measured on day 32(Fig.2)indicated that only 22%of the biomass was made of granular sludge with diameter largerthan 0.2mm.These results suggest that sludge settleability increased prior to granule formation and was not affected by different particle sizes in the sludge during the GSBR operation.It was observed,however,that the diameter of the granules fluctuated over longer durations.The large granules tended to destabilize due to endogenous respiration,and broke into smaller granules that could seed the formation of large granules again.Pochana and Keller reported that physically broken sludge flocs contribute to lower denitrification rates,due to their reduced anoxic zone (Pochana and Keller,1999).Therefore,TN removal efficiency raises fluctuantly throughout the experiment.Some previous research had demonstrated that bigger,more dense granules favored the enrichment of PAO (Winkler et al.,2011a ).Hence,after day 77,removal efficiency of TP was higher and relatively stable because the granules mass fraction was over 90%and more larger granules formed.4.2.Relationship between AOB communities dynamic and sludge granulationFor granule formation,a short settling time was set,and only particles with a settling velocity higher than 4.5m h À1were retained in the reactor.Moreover,as shown in Fig.1,the variation in SVI 10was greater before day 41(from 108.2mL g À1e 34.1mL g À1).During this phase,large amounts of biomass could not survive in the reactor.A clear shift in pop-ulations was evident,with 58%similarity between days 8and 18(Table S1).In the SBR system fed with acetate-based synthetic wastewater,heterotrophic bacteria can produce much larger amounts of extracellular polysaccharides than autotrophic bacteria (Tsuneda et al.,2003).Some researchers found that microorganisms in high shear environments adhered by extracellular polymeric substances (EPS)to resist the damage of suspended cells by environmental forces (Trinet et al.,1991).Additionally,it had been proved that the dominant heterotrophic species in the inoculating sludge were preserved throughout the process in our previous research (Zhang et al.,2011).It is well known that AOB are chemoau-totrophic and slow-growing;accordingly,numerous AOBw a t e r r e s e a r c h x x x (2011)1e 106populations that cannot become big and dense enough to settle fast were washed out from the system.As a result,the variation in AOB was remarkable in the period of sludge inoculation,and the diversity index of population decreased rapidly.After day 45,AOB communities’structure became stable due to the improvement of sludge settleability and the retention of more biomass.These results suggest that the short settling time (selection pressure)apparently stressed the biomass,leading to a violent dynamic of AOB communities.Further,these results suggest that certain populations may have been responsible for the operational success of the GSBR and were able to persist despite the large fluctuations in pop-ulation similarity.This bacterial population instability,coupled with a generally acceptable bioreactor performance,is congruent with the results obtained from a membrane biore-actor (MBR)for graywater treatment (Stamper et al.,2003).Nitrosomonas e like and Nitrosospira e like populations are the dominant AOB populations in wastewater treatment systems (Kowalchuk and Stephen,2001).A few previous studies revealed that the predominant populations in AOB communities are different in various wastewater treatment processes (Tawan et al.,2005;Thomas et al.,2010).Some researchers found that the community was dominated by AOB from the genus Nitrosospira in MBRs (Zhang et al.,2010),whereas Nitrosomonas sp.is the predominant population in biofilter sludge (Yin and Xu,2009).In the currentstudy,Fig.5e DGGE profile of the AOB communities in different size of granules (lane labels along the top show the range of particle diameter (d,mm)).Values along the bottom indicate the Shannon diversity index (H ).Bands labeled with the numbers were consistent with the bands in Fig.3.w a t e r r e s e a r c h x x x (2011)1e 107sequence analysis revealed that selection pressure evidently effect on the survival of Nitrosospira in granular sludge.Almost all of Nitrosospira were washed out initially and had no chance to evolve with the environmental changes.However,some members of Nitrosomonas sp.have been shown to produce more amounts of EPS than Nitrosospira ,especially under limited ammonia conditions (Stehr et al.,1995);and this feature has also been observed for other members of the same lineage.Accordingly,these EPS are helpful to communicate cells with each other and granulate sludge (Adav et al.,2008).Therefore,most of Nitrosomonas could adapt to this challenge (to become big and dense enough to settle fast)and were retained in the reactor.At the end of reactor operation (day 180),granules with different particle size were sieved.The effects of variation in granules size on the composition of the AOBcommunitiesFig.6e Micrographs of FISH performed on three size classes of granule sections.DAPI stain micrographs (A,D,G);AOB appear as green fluorescence (B,E,H),and NOB appear as red fluorescence (C,F,I).Bar [100m m in (A)e (C)and (G)e (I).d,particle diameter.(For interpretation of the references to colour in this figure legend,the reader is referred to the web version of this article.)w a t e r r e s e a r c h x x x (2011)1e 108were investigated.As shown in Fig.5,AOB communities structures in different size of granules were varied.Although several predominant bands(bands2,5,11)were present in all samples,only bands3and6appeared in the granules with diameters larger than0.6mm.Additionally,bands7and10 were intense in the granules larger than0.45mm.According to Table2,it can be clearly indicated that Nitrosospira could be retained merely in the granules larger than0.6mm.Therefore, Nitrosospira was not present at a high level in Fig.3due to the lower proportion of larger granules(d>0.6mm)in TSS along with reactor operation.DGGE analysis also revealed that larger granules had a greater microbial diversity than smaller ones. This result also demonstrates that more organisms can survive in larger granules as a result of more space,which can provide the suitable environment for the growth of microbes(Fig.6).4.3.Effect of variance in particle size on the distribution of AOB and NOB in granulesAlthough an influence of granule size has been observed in experiments and simulations for simultaneous N-and P-removal(de Kreuk et al.,2007),the effect of granule size on the distribution of different biomass species need be revealed further with the assistance of visible experimental results, especially in the same granular sludge reactors.Related studies on the diversity of bacterial communities in granular sludge often focus on the distribution of important functional bacteria populations in single-size granules(Matsumoto et al., 2010).In the present study,different size granules were sieved,and the distribution patterns of AOB and NOB were explored.In the nitrification processes considered,AOB and NOB compete for space and oxygen in the granules(Volcke et al.,2010).Since ammonium oxidizers have a higheroxygen affinity(K AOBO2<K NOBO2)and accumulate more rapidly inthe reactor than nitrite oxidizers(Volcke et al.,2010),NOB are located just below the layer of AOB,where still some oxygen is present and allows ready access to the nitrite produced.In smaller granules,the location boundaries of the both biomass species were distinct due to the limited existence space provided by granules for both microorganism’s growth.AOB exist outside of the granules where oxygen and ammonia are present.Medium granules can provide broader space for microbe multiplying;accordingly,AOB spread out in the whole granules.This result also confirms that oxygen could penetrate deep into the granule’s core without restriction when particle diameter is less than0.6mm.Some mathematic model also supposed that NOBs are favored to grow in smaller granules because of the higher fractional aerobic volume (Volcke et al.,2010).As shown in the results of the batch experiments(Zhang et al.,2011),nitrite accumulation temporarily occurred,accompanied by the more large gran-ules(d>0.9mm)forming.This phenomenon can be attrib-uted to the increased ammonium surface load associated with larger granules and smaller aerobic volume fraction,resulting in outcompetes of NOB.It also suggests that the core areas of large granules(d>0.9mm)could provide anoxic environment for the growth of anaerobic denitrificans(such as Tb.deni-trificans or Tb.thioparus in Fig.S7,Supporting information).As shown in Fig.2and Fig.S3,the removal efficiency of total nitrogen increased with formation of larger granules.5.ConclusionsThe variation in AOB communities’structure was remarkable during sludge inoculation,and the diversity index of pop-ulation decreased rapidly.Most of Nitrosomonas in the inocu-lating sludge were retained because of their capability to rapidly adapt to the settling e washing out action.DGGE anal-ysis also revealed that larger granules had greater AOB diversity than that of smaller ones.Oxygen penetration was not restricted in the granules of less than0.6mm particle diameter.However,the larger granules(d>0.9mm)can result in the smaller aerobic volume fraction and inhibition of NOB growth.Henceforth,further studies on controlling and opti-mizing distribution of granule size could be beneficial to the nitrogen removal and expansive application of granular sludge technology.AcknowledgmentsThis work was supported by grants from the National Natural Science Foundation of China(No.51108456,50908227)and the National High Technology Research and Development Program of China(No.2009AA06Z312).Appendix.Supplementary dataSupplementary data associated with this article can be found in online version at doi:10.1016/j.watres.2011.09.026.r e f e r e n c e sAdav,S.S.,Lee, D.J.,Show,K.Y.,2008.Aerobic granular sludge:recent advances.Biotechnology Advances26,411e423.APHA-AWWA-WEF,2005.Standard Methods for the Examination of Water and Wastewater,first ed.American Public Health Association/American Water Works Association/WaterEnvironment Federation,Washington,DC.de Bruin,L.M.,de Kreuk,M.,van der Roest,H.F.,Uijterlinde,C., van Loosdrecht,M.C.M.,2004.Aerobic granular sludgetechnology:an alternative to activated sludge?Water Science and Technology49,1e7.de Kreuk,M.,Heijnen,J.J.,van Loosdrecht,M.C.M.,2005.Simultaneous COD,nitrogen,and phosphate removal byaerobic granular sludge.Biotechnology and Bioengineering90, 761e769.de Kreuk,M.,Picioreanu,C.,Hosseini,M.,Xavier,J.B.,van Loosdrecht,M.C.M.,2007.Kinetic model of a granular sludge SBR:influences on nutrient removal.Biotechnology andBioengineering97,801e815.Downing,L.S.,Nerenberg,R.,2008.Total nitrogen removal ina hybrid,membrane-aerated activated sludge process.WaterResearch42,3697e3708.Erguder,T.H.,Boon,N.,Vlaeminck,S.E.,Verstraete,W.,2008.Partial nitrification achieved by pulse sulfide doses ina sequential batch reactor.Environmental Science andTechnology42,8715e8720.w a t e r r e s e a r c h x x x(2011)1e109。
寡营养细菌文献综述
海洋中寡营养细菌的分离培养技术及环境适应机制研究进展摘要：生存于北极海洋的细菌归属于极端微生物,它们是目前发现最古老的生物类群。
来自北极的细菌具有极强的环境适应能力,能够在北极地区独特气候形成的强酸碱、干燥、强辐射、高盐、高压、寒冷、寡营养等极端环境下生存繁衍。
独特的生存环境造就了北极细菌独特的代谢水平上的适应机制和分子水平上的代谢机制,这些独特的生物在北极地区生态系统循环中发挥着不可或缺的作用。
与此同时,它们还蕴藏着生命的起源、遗传、进化和巨大的工业用途等多方面的奥秘。
然而,对于人类研究而言,如此庞大的极端微生物资源库中,绝大多数还是未知菌。
Ekeiof于1908年首次报道了他分离自南极的微生物,从此以后,极地作为潜在微生物资源库,逐渐引起人类的广泛关注,成为了研究热点。
对北极微生物多样性的研究,将会为人类发掘利用北极地区微生物的物种资源和基因资源提供理论依据。
对极地细菌的分离鉴定,将会为人类带来产生生物活性物质的新菌株,而这些生物活性物质很可能是新型药物、生物保健品的源泉,具有重要的工业应用价值。
1、前言：早在1959 年, 人们就认识到在琼脂平板上可培养的微生物和通过显微计数测得的微生物相差好几个数量级。
1987 年Carl Woese 通过生物核糖体RNA的序列分析提出了生物体三域的学说, 自此, 16SrRNA 的系统分类学研究日见广泛地应用于环境微生物分析。
这种基于DNA/RNA 测序技术与序列分析的方法不依赖于传统的微生物培养技术, 极大的拓宽了人们对地球上微生物多样性的认识。
至今为止, 在人类已知的原核生物53 个门的分类单元中只有26 个门囊括了经过实验室培养的细菌[1,2]。
在可培养微生物的16S rRNA 基因库中, 紫色光合菌(Proteobacteria) 等细菌(包括Cytophagales 和两类革兰氏阳性菌:Actinobacteria 和低G+C 含量菌)占所有已知细菌的90%[3]。
文献阅读报告
利用微电极原位测量生物膜中、沉积物以及微生物垫微生物活性Introduction在过去的一百年，微生物学家已经阐明微生物种类和代谢的巨大变化。
在微生物代谢和不同微生物过程之间的关系已经取得突破性的成就。
然而自然环境的微生物活性的具体研究仍然受到微生物学传统方法的限制：在特定条件下菌株的分离培养。
这种基本的方法只提供相关电位和活性微生物的活动的信息。
然而，在大部分水生系统中，在沉积物、微生物垫、悬浮絮状物或附着于固体表面的生物膜中的多物种群落中，通过微生物固化出现大量微生物转化。
基质供应和单个细胞单元的处理受到这些结构中还原反应或缺乏自由对流的限制，从而限制了转化速率。
为了了解原位活性，须要考虑两方面：（1）微环境原位变化可以发生在很小的范围内；（2）同种群之间相互作用的重要性。
相关联的例子很多如，微生物垫、生物膜、浮游生物以及沉积物甚至微生物病原体及其宿主。
微传感器用于微生物生态学中的微传感器是尖端直径为1-20微米的针形仪器，用其测量特定化合物的浓度。
由于其尖端感应区尺寸小使得在生物膜、絮体、微生物垫和沉积物中原位测量成为可能。
目前，四中不同原理的的微传感器分别有：安培型、伏安型、电位型和光学微传感器。
最近，伏安微传感器应用于微生物生态学中，不过这种类型的传感器目前只用于特定情况下。
电流型传感器中氧气微传感器是最常用的传感器，已经用于很多研究领域中研究光合作用和呼吸作用。
氧气微传感器也是用于微生物生态学中最早的传感器，所以也是最可靠的传感器。
氧微传感器工作原理详述如下,氧通过硅膜扩散至尖端直径为22-10微米的感应区，在靠近尖端的阴极减少，产生电流正比于尖端附近氧的浓度。
安培微传感器的选择性有一下三个因素决定：（1）应用极化电位；（2）尖端膜的特定渗透性；（3）也是氧化还原特性的需要。
各种测量分析物通过使用传感器中作为氧化还原化合物的形成或消耗的催化剂的纯化酶或整个细菌细胞被扩大。
所有安培型微传感器尤其是微型生物传感器的一个严重缺点是其复杂性。
文献阅读：鲍曼不动杆菌感染和治疗的研究进展
一项针对黏菌素耐药鲍曼不动杆菌的体外实验结果显示，黏菌素与舒巴坦联用时，黏菌素的 MIC 从单用时的 32 mg·L-1降低到 4 mg·L-1，而舒巴坦的 MIC 从单用时的 2 mg·L-1降低到 0.5 mg·L-1
对鲍曼不动杆菌感染临床案例的mate分析显示，黏菌素与舒巴坦的联合疗法与黏菌素单药相比，表现出良好的微生物治愈率（RR=1.21, 95% CI: 1.06~1.38）以及近乎相同的安全性，黏菌素、舒巴坦和替加环素三联疗法是治愈率最高的一种药物联用组合
1
鲍曼不动杆菌在环境中持续存在的能力可能是由于它能够在非生物和生物表面形成生物膜。生物膜形成也是设备相关感染的发病机制，并通过延长在无生命物体上的存活时间提供了重复传播的来源。在恶劣的环境条件下，生物膜深处的鲍曼不动杆菌细胞可以经历休眠，变得代谢不活跃，并对环境压力保持旺盛。 在鲍曼不动杆菌中发现的多重抗生素耐药机制也可能在其环境生存中发挥作用。
鲍曼不动杆菌感染分布的特点
Giammanco A, Calà C[J]. mSphere, 2017, 2(1): 310-316.
全球对左氧氟沙星的耐药性从 2004 年的 92% (283/309)显著增加到 2014 年的 96% (430/447)，哌拉西林-他唑巴坦的耐药性从 2004 年的 82% (252/309)显著增加到 94%(422/447)(P < 0.0001)
鲍曼不动杆菌耐药情况
Asif M, Alvi I A, Rehman S Infect Drug Resist, 2018, 11: 1249-1260.
鲍曼不动杆菌耐药情况
Asif M, Alvi I A, Rehman S Infect Drug Resist, 2018, 11: 1249-1260.
水中微生物的种类和含量文献
水中微生物的种类和含量文献水中微生物的种类和含量研究是环境生物学领域的热门课题之一、水中微生物是指那些在水体中生活并具有微小体型的微生物群体，包括细菌、真菌、病毒、藻类等。
研究水中微生物的种类和含量可以帮助我们了解水体生态系统的健康状况、水质污染程度、环境变化对微生物群落的影响等问题，对于水体的保护与治理具有重要意义。
在过去的几十年中，随着分子生物学和生物技术的发展，研究人员们开展了大量的水中微生物调查与分析工作。
这些研究使用了多种方法，如传统培养与鉴定技术、分子生物学方法和高通量测序技术等，以获得水中微生物种类和含量的信息。
关于水中微生物的种类，研究表明，水体中微生物的多样性极其丰富，包括成千上万种不同的细菌、真菌、病毒和藻类。
其中，细菌是水中微生物群落的主要组成部分，占据着最大的比例。
此外，一些特定的微生物群落也会存在于一些特殊的水体环境中，如热泉、盐湖、寒冷环境等。
这些微生物群落具有独特的适应特性和生态功能，成为生态系统中的重要组成部分。
水中微生物的含量在不同水体中具有巨大的差异。
研究发现，水体的理化因素，如水温、营养盐含量、溶解氧浓度等，对水中微生物的种类和含量具有重要影响。
在常规调查中，常用的测定水中微生物含量的方法包括直接计数方法和生物标记物测定法。
直接计数方法通常通过显微镜观察，对采集的水样中微生物的数量进行统计。
生物标记物测定法则通过检测微生物特定的生物标志物，如DNA、RNA、蛋白质等，来估算微生物的含量。
近年来，随着高通量测序技术的快速发展，研究人员开始通过对水样进行宏基因组测序或16S/18SrRNA基因序列分析，来获取更加详细的水中微生物群落信息。
这些研究揭示了微生物组成的复杂性与多样性，丰富了我们对水中微生物群落结构及其功能的认识。
此外，近年来还有一些关于水中微生物种类和含量的相关研究。
例如，研究人员使用16SrRNA测序技术对河流和湖泊水中微生物群落进行了测定和比较，发现不同水体类型中微生物群落的差异性，以及与水质参数之间的关联性。
微生物专题英文文献
3、Materials and methods
供试菌种 黑曲霉A3（褐黑色）
培养基 孢子培养基：马铃薯、葡萄糖、琼脂、去离子水 菌种培养基：PDA培养基 摇瓶发酵培养基：玉米穗、麸皮、（NH4）2SO4、NaNO3 分离培养基：蛋白胨、琼脂、麸皮
矿质元素、生长因子：KH2PO4、MgSO4、FeSO4、CoCl2
试验流程
收集孢子 制备菌悬液 稀释制膜（自然干燥） 离子注入 洗脱、涂布平皿、28o培养 挑选单菌落 优良菌株
高产菌株
酶活力检测
产孢子斜面
发酵
N 注入参 数
+
不同的碳源
培养工艺 的优化
不同的氮源
培养基优化的正交设计
4、Results and dicussion
4.1 N+ 注射量和不同能量的离子束对黑曲霉A3 存活率的影响
2、Introduction
Generally xylan is a major hemicellose component of the cell walls of a higher yield plant.In a pure state it is composed of monomers of D-xylose, linked through β-1,4 glycosidic linkages. The hydrolysis of β-linkages in different polymeric carbohydrates, including β xylans, is carried out by several enzymes produced by a wide range of micro-organisms such as fungi, actinomycettes and eubacteria.
肠道微生物转录组文献解读
肠道微生物转录组文献解读
引言：
肠道微生物转录组是指肠道中所有微生物的基因转录
表达情况。
近年来，随着高通量测序技术的发展，肠道微生物转录组研究已成为探索肠道微生物与人体健康关系的重
要手段。
本文通过对近期相关文献的解读，探讨肠道微生物转录组的研究进展及其在疾病诊断、治疗和预防等方面的应用前景。
材料与方法：
本文选取了近五年内发表的肠道微生物转录组相关文献，采用文献综述和归纳总结的方法进行解读。
结果：
通过对文献的梳理，我们发现肠道微生物转录组的研究主要集中在以下几个方面：（1）肠道微生物转录组的组成和变化规律；（2）肠道微生物转录组与人体健康的关系；（3）肠道微生物转录组在疾病诊断、治疗和预防中的应用。
讨论：
肠道微生物转录组研究对于深入了解肠道微生物与人
体健康的关系具有重要意义。
通过对肠道微生物转录组的调控，可以实现对肠道微生物的定向调控，从而达到预防和治疗疾病的目的。
然而，目前肠道微生物转录组研究仍存在一些挑战，如样本采集、数据分析和解读的标准化等。
因此，
需要进一步加强研究，完善研究方法和技术体系，为肠道微生物转录组的应用提供更加可靠的依据。
结论：
肠道微生物转录组研究在疾病诊断、治疗和预防等方面具有广阔的应用前景。
未来需要加强跨学科合作，深入研究肠道微生物转录组的调控机制和影响因素，推动肠道微生物转录组研究的发展，为人类健康提供更多有益的探索。
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微生物文献阅读
关于微生物降解的研究进展
摘要：塑料工业的崛起, 促进了科学技术和工农业的高速发展, 1992 年世界塑料产量达1亿吨/ 年, 各种塑料制品的需求量与日俱增, 但同时也带来废旧塑料“白色污染”的公害, 废弃塑料大约4000 万吨/ 年, 且数量正以惊人的速度增长[1]。
合成高分子(树脂) 所制成的塑料已得到广泛应用。
本文详细介绍了生物降解塑料包括天然高分子合成、微生物发酵合成、人工合成及可溶性生物降解塑料的国内外发展概况。
以及在我国开展生物降解塑料[2]研究的重要意义, 指出生物降解塑料是解决白色污染的理想途径。
关键词：微生物合成生物降解塑料发展
降解性塑料根据其降解机理大致可分为光降解塑料和生物降解塑料[3]。
当前，为了改善降解塑料的降解性能，又发展了光-生物双降解塑料。
可光降解塑料是高分子链能用光化学方法使之破坏，塑料就失去它的物理强度并脆化，再经自然界的剥蚀(风、雨等)碎为细脆化, 最后变为粉末, 进入土壤，在微生物作用下重新进人生物循环。
生物可降解塑料按降解机理[4]和破坏方式可分为完全生物降解型，和生物破坏性塑料两种。
完全生物降解型塑料主要采用天然高分子材料如淀粉、废糖蜜和具有生物降解性的合成高分子材料，或水溶性高分子材料以及利用微生物发酵法可降解塑料。
生物破坏性塑料是对材料水平而言的, 主要是天然高分子与通用型合成高分子通过共混或共聚而制成的降解塑料。
光-生物降解塑料[5]是利用光降解机理和生物降解机理相结合的方法制得的一类塑料，是一种比较理想的降解塑料。
可降解塑料的研究是一个环境科学、高分子化学、生物学交叉的全新领域[6]。
可降解塑料以生物资源为原料, 取代了不可再生的化石资源，如石油和煤炭等；在生态环境中会完全降解为水和二氧化碳, 最重要的是可以节约能源、保护环境，实现资源与环境的可持续发展。
PHA(聚羟基烷酸)正是在这种情况下发展起来的一类高分子材料。
目前，微生物合成出的PHA有均聚物、共混物和无规共聚物, 其性能可在塑料和橡胶间变化。
已鉴定的PHA约有40种，其中PHB(聚B-羟基丁酸)是PHA 的典型代表。
PHB 是细菌体内一种酯类的累积物，主要被用作碳源和能源的储备物。
由于具有低溶解性和相对高的摩尔质量, 故PHB可以在细菌胞内大量储存而不影响胞内外的渗透压，是一种理想的储存材料。
当增加碳氮比后，细菌体内的PHB含量就会增加；当细菌缺乏足够的营养供应而不能分裂和生长时也积累PHB。
与传统的化学合成高分子相比，PHB作为一种微生物合成塑料，不仅具有化学合成塑料的特性，而且还有如下特点：密度大、光学活性好、透氧性低、抗紫外线辐射、生物可降解性、生物组织相容性、压电性和抗凝血性等[7], 可望在电子、光学、生物医学等高技术领域获得应用。
PHB应用的另一个重要领域是其单体的应用。
它的每一个结构单元都有一个手性碳,可用于色谱分析,以分离光学异构体；另外, PHB水解后得到的B-羟基丁酸单元体可作为有机物合成的原料, 制备手性衍生物。
回顾中国生物降解塑料的研究开发历程,发现产业界和学术界各自独立开展
工作,交流很少。
产业界盲目引进了多条聚烯烃/淀粉塑料生产线[8]，学术界独立开展全生物降解塑料的研究，未能和产业界紧密结合，结果，影响了中国生物降解塑料发展。
今后，在生物降解塑料的研发进程中，要加强学术界和产业界的联系和交流，促进中国生物降解塑料的健康发展。
在应用领域, 降解塑料地膜经上世纪90 年代的大规模试验, 其结果表明了降解塑料地膜降解和应用的复杂性, 同一配方的降解塑料地膜在不同的地方、对不同的作物有不同的降解表现[9], 必须通过应用研究才能推广使用。
为此, 降解塑料地膜的实际推广受到了阻碍, 虽然有需求, 但是, 应用终未能走向普及。
降解塑料在地膜上的应用还是一个未能解决的问题，是今后需要进一步开发的应用领域。
在大量的一次性使用的塑料包装袋、餐具等应用领域, 用生物降解塑料去替代不可降解塑料, 因受到经济原因的制约, 也尚未形成其应有的市场。
在这一领域, 生物降解塑料的任务是进一步降低成本, 提高性能, 推进市场化。
生物降解塑料在其他领域的应用, 如卫生用品、光盘盒、文具、家电零部件方面的应用应该引起重视。
微生物塑料是塑料家族中带降解功能的一类新型的天然高分子材料[10]，它为人类展示了一个环境科学、化学、生物学等多学科交叉的全新科学领域[11]。
虽然目前存在许多问题, 但它符合现代社会的要求, 其技术含量高, 是开发的热点。
我们相信，随着技术的进步，性能的不断提高和成本的降低，公众环保意识的增强，微生物塑料的应用将越来越广泛。
21世纪是经济、资源、能源、环保相互协调、经济持续发展的时代, 微生物塑料的研究开发和应用, 无论从环保角度还是从其自身的学术角度都有重要意义, 前景是很乐观的。
参考文献
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