微生物英文文献及翻译—原文
- 格式：pdf
- 大小：1.11 MB
- 文档页数：10
下载文档原格式
合集下载
微生物专题英文文献共24页文档
谢谢！
微生物专题ห้องสมุดไป่ตู้文文献
11、战争满足了，或曾经满足过人的 好斗的 本能， 但它同 时还满 足了人 对掠夺 ，破坏 以及残 酷的纪 律和专 制力的 欲望。 ——查·埃利奥 特 12、不应把纪律仅仅看成教育的手段 。纪律 是教育 过程的 结果， 首先是 学生集 体表现 在一切 生活领 域—— 生产、 日常生 活、学 校、文 化等领 域中努 力的结 果。— —马卡 连柯(名 言网)
13、遵守纪律的风气的培养，只有领 导者本 身在这 方面以 身作则 才能收 到成效 。—— 马卡连 柯 14、劳动者的组织性、纪律性、坚毅 精神以 及同全 世界劳 动者的 团结一 致，是 取得最 后胜利 的保证 。—— 列宁 摘自名言网
15、机会是不守纪律的。——雨果
61、奢侈是舒适的，否则就不是奢侈 。——CocoCha nel 62、少而好学，如日出之阳；壮而好学 ，如日 中之光 ；志而 好学， 如炳烛 之光。 ——刘 向 63、三军可夺帅也，匹夫不可夺志也。 ——孔 丘 64、人生就是学校。在那里，与其说好 的教师 是幸福 ，不如 说好的 教师是 不幸。 ——海 贝尔 65、接受挑战，就可以享受胜利的喜悦 。——杰纳勒 尔·乔治·S·巴顿
临床微生物细菌-英文版
Chaper 1 Chapter 3
Bacteria
Introduction
Bacteria
Size, Shape, and Arrangement of Bacterial Cells Most bacteria fall within a range
Cm = 10-2 meter mm = 10-3 meter μm = 10-6 meter nm = 10-9 meter
Staphylococcus - facultatively anaerobic, grampositive, usually form irregular clusters, nonmotile, catalase positive but oxidase negativeally.
Representatives: Escherchia col Prote
Pseudomonas
Vibrio, Spirillum and Spirochete
vibrio
spirillum
spirochete
Some bacteria are shaped like long rods twisted into spirals or helices; they are called vibrios (like commas or incomplete spirals), spirilla if rigid and spirochetes when flexable.
Clostridium – Anaerobic
Clostridium botulinus C. butyricum C. aceticum C. tetani C. putrificum
Nonspore - forming rod shaped bacteria
Bacteria
Introduction
Bacteria
Size, Shape, and Arrangement of Bacterial Cells Most bacteria fall within a range
Cm = 10-2 meter mm = 10-3 meter μm = 10-6 meter nm = 10-9 meter
Staphylococcus - facultatively anaerobic, grampositive, usually form irregular clusters, nonmotile, catalase positive but oxidase negativeally.
Representatives: Escherchia col Prote
Pseudomonas
Vibrio, Spirillum and Spirochete
vibrio
spirillum
spirochete
Some bacteria are shaped like long rods twisted into spirals or helices; they are called vibrios (like commas or incomplete spirals), spirilla if rigid and spirochetes when flexable.
Clostridium – Anaerobic
Clostridium botulinus C. butyricum C. aceticum C. tetani C. putrificum
Nonspore - forming rod shaped bacteria
文献翻译-保持微创新鲜已加工果蔬的微生物和感官质量的新兴技术
Emerging technologies for keeping microbial and sensory quality of minimally fresh processed fruits and vegetablesThe emphasis in post-harvest fruit protection against quality attributes losses, physiological disorders, diseases and insects has shifted from using agro-chemicals to various alternative techniques, including biological control, cultural adaptations and physical methods such as controlled atmosphere (CA), MAP and irradiation. Given the restrictions of chemical use in plant foods and because many of them cause ecological problems or are potentially harmful to humans and may be withdrawn from use, the advantage of these alternative techniques is that no chemicals are involved (Artés, 1995; Graham and Stevenson, 1997; Reddy et al., 1998; Mathre et al., 1999; Sanz et al., 1999; Daugaard, 2000; Harker et al., 2000; Marquenie et al., 2003). Additionally, preservation techniques are becoming milder in response to demands of consumers for higher quality, more convenient foods that are less heavily processed and preserved and less reliant on chemical preservatives (Abee and Wounters, 1999).The unique way to assure microbial and sensory quality of minimally fresh processed plant products relies on refrigerated storage and distribution, although combination of refrigeration and subinhibitory preservation techniques could prolong their shelf-life.As mentioned above, many non-conventional methods are now being investigated; however, there are some limitations to their application since some methods are not applicable to fresh-cut fruits and vegetables because of damage to plant tissue but only to liquid foods such as fruit juices (Carlin and Nguyen-the, 1997). Therefore, in this section those techniques that can be used to preserve fresh processed plant foods will be revised.The most critical step in the production chain of minimal fresh processing of fruits and vegetables is washing-disinfection. For this reason, special attention to the alternative sanitizing agents as well as the new technologies for disinfection of these commodities will be given. To develop or improve washing and sanitizing treatments, special attention should be paid to the compatibility of treatments with commercial practices, cost, absence of induced adverse effects on product quality and the need for regulatory approval and consumer acceptance (Sapers, 2001). Some alternatives to sanitizing agents are: O3, ClO2, peracetic acid (about 90–100 ppm), H2O2, organic acids (acetic, lactic, citric, malic, sorbic and propionic acids at 300–500 mg/ml), electrolysed water, radio frequency, hot water treatments and UV-C radiation (Adams et al., 1989;Masson, 1990; Castañer et al., 1996; Tomás-Barberán et al., 1997; Delaquis et al., 1999, 2000, 2004; Sapers, 2001; Suslow, 2002; Jacxsens, 2002; Aguayo, 2003; Allende, 2003).1. Hydrogen peroxideTreatments of hydrogen peroxide (H2O2) seem to be a promising alternative to chlorine for disinfecting minimally fresh processed vegetables (Soliva-Fortuny and Martín-Belloso, 2003). H2O2 is generally recognized as safe (GRAS) for some food applications, but has not yet been approved as an antimicrobial wash. It does not produce residues since it is rapidly decomposed by the enzyme catalase to water and O2 (Sapers, 2001). Various experimental antimicrobial applications of H2O2 for foods have been described, including preservation of vegetable salads, berries and fresh-cut melons (Hagenmaier and Baker, 1997) since it reduces microbial populations and extends the shelf-life without causing loss of quality. Sapers and Simmons (1998) recommended its use for fresh-cut melon as it extended the shelf-life for 4–5 days in comparison to chlorine treatments. However, they demonstrated that H2O2 is injurious to some commodities, causing bleaching of anthocyanins in mechanically damaged berries. H2O2 vapour delayed or reduced the severity of bacterial soft rot in fresh processed cucumber, green bell pepper and zucchini, but no effect on spoilage of fresh-cut broccoli was found (Hagenmaier and Baker, 1997). Additionally, an extended shelf-life was found in fresh processed cucumbers, green bell peppers and zucchini after washing in a 5–10 per cent solution of H2O2 for 2 min (Sapers and Simmons, 1998). It means that the applicability of H2O2 to a broad range of minimally fresh processed vegetables should be determined, especially with commodities that are subject to rapid spoilage.2. Acidic electrolysed waterThis is a new disinfectant technique for fresh produce that has been shown to be efficient due to its antimicrobial and antiviral activities for fruit and vegetables (Izumi, 1999; Koseki and Itoh, 2000). Electrolysis of water containing a small amount of sodium chloride generates a highly acidic hypochlorous acid solution containing 10–100 ppm of available chlorine. Koseki et al. (2001) found that acidic electrolysed water (pH 2.6, oxidation reduction potential, 1140mV; 30 ppm of available chlorine) reduced viable aerobes in shredded lettuce by 2 log cfu/g within 10 min, showing a higher disinfectant effect than ozonated water. They reported that the use of this new technique could be applicable for food factory hygiene, meaning that the use of acidic electrolysed water at home or restaurant kitchen just before eating fresh fruits and vegetables could preventpoisoning.According to this, Park et al. (2002) reported population reductions on lettuce leaves exceeding2.49 log units for E. coli O157:H7 and L. monocytogenes and Horton et al. (1998) reported population reductions of E. coli O157:H7 on apples of3.7–4.6 log units cfu/g. However, Izumi (1999) only found 1 log unit cfu/g reduction in the microbial population of fresh-cut vegetables.3. Chlorine dioxideChlorine dioxide (ClO2) is a strong oxidizing agent (about 2.5 times the oxidative capacity of chlorine) having a broad biocide efficacy (Singh et al., 2002), including a good biofilm penetration. To date, the FDA (USFDA, 1998) has allowed the use of aqueous ClO2 in washing of uncut and unpeeled fruit and vegetables. However, ClO2 is unstable and it must be generated on-site and can be explosive when concentrated (Jacxsens, 2002). Zhang and Farber (1996) found that the initial microbial load decreased by 1 log cycle of cfu/g for shredded lettuce inoculated with L. monocytogenes at levels of 5 mg/l ClO2 in aqueous solution. However, Reina et al. (1995) found that bacterial populations present on fresh processed cucumbers were not greatly influenced by ClO2 treatment, even at concentration of 5.1 mg/l. More recently, Singh et al. (2002) found that increasing the concentration of ClO2 in deionized water (5 mg/l for 1 and 5 min) resulted in a decrease in E. coli O157:H7 population on lettuce and baby carrots in comparison to washing with deionized water (control) for the same period.Increasing the washing period from 1 to 15 min with aqueous ClO2 (5 mg/l) showed no significant reduction in the population of E. coli O157:H7 on shredded lettuce. However, after washing baby carrots a reduction in E. coli O157:H7 was found.4. Organic acidsSeveral organic acids have been tested as alternative disinfectants to sanitize fresh-cut vegetable surfaces (Hilgren and Salverda, 2000). They may retard and/or prevent the growth of some microorganisms (Beuchat, 1998). Their antimicrobial activity is not generally due to killing of the cells but they affect the cells’ ability to maintain pH homeostasis, disrupting substrate transport and inhibiting metabolic pathways (Seymour, 1999). Peracetic acid has been recommended for treatment of process water (Hilgren and Salverda, 2000); however, population reductions for aerobic bacteria, coliforms, yeast and moulds on fresh-cut celery, cabbage and potatoes, treated with 80 ppm peracetic acid, were less than 1.5 log units cfu/g (Forney et al., 1991). Wright etal. (2000) obtained a 2 log units cfu/g reduction in apple slices inoculated with E. coli O157:H7 using 80 ppm peracetic acid, with an interval of 30 min between inoculation and treatment.On the other hand, Wisniewsky et al. (2000) found a reduction of less than 1 log unit cfu/g at the same concentration but in an interval of 24 h. Citric acid has been proposed as a very good coadjutant to the washing of fresh-cut fruit and vegetables due to its antibrowning power. It is a phenolase Cu-chelating agent and the inhibition of PPO was attributed to its chelating action (Jiang et al., 1999). Santerre et al. (1988) reported that application of citric acid can prevent browning of sliced apple thus extending shelf-life and it was shown that the combination of citric acid and ascorbic acid exhibited even more beneficial effects (Pizzocaro et al., 1993). Additionally, Jiang et al. (2004) found that the application of citric acid was effective in extending shelf-life and maintaining the quality of fresh-cut Chinese water chestnut slices during storage.5. OzoneOzone (O3) is a strong oxidant and potent disinfecting agent and, when it is applied to food, it leaves no residues since it decomposes quickly. The biocide effect of O3 is caused by a combination of its high oxidation potential, reacting with organic material up to 3000 times faster than chlorine (EPRI, 1997). Even though it is new for the USA, it has been utilized in European countries for a long time (Guzel-Seydima et al., 2004).For instance, it has been commonly used as a sanitizer in water treatment plants since the early 1900s (Gomella, 1972) and also for disinfection of swimming pools, sewage plants, disinfection of bottled water and prevention of fouling of cooling towers in Europe (Gomella, 1972; Rice et al., 1981; Legeron, 1982; Schneider, 1982; Echols and Mayne, 1990; Costerton, 1994; Videla et al., 1995; Strittmatter et al., 1996). In 1997, an expert panel decreed that O3 was a GRAS substance for use as a disinfectant or sanitizer for foods when used in accordance with good manufacturing practices in the USA (Suslow, 2003) and it has now been approved for use as a disinfectant or sanitizer in foods and food processing in the USA (USDA, 1997, 1998). The bactericidal action of O3 has been studied and documented on a wide variety of organisms, including those that are resistant to chlorine, extending the shelf-life of a number of fruit and vegetables (Fetner and Ingols, 1956; Norton et al., 1968; Rice et al., 1982; Foegeding, 1985; Ishizaki et al., 1986; Foegeding and Busta, 1991; Restaino et al., 1995; Beuchat, 1998; Richardson et al., 1998; Aguayo, 2003). In fact, it has been proven thatO3 is suitable for washing and sanitizing solid food with intact and smooth surfaces (e.g. fruit and vegetables) and ozone-sanitized fresh produce has recently been introduced in the USA market. The use of O3 to sanitize equipment, packaging materials and the processing environment is currently being investigated (Kim et al.,2003). The modus operandi of O3 implicates the destruction of microorganisms by the progressive oxidationof vital cellular components. The bacterial cell surface has been suggested as the primary target of ozonation (Guzel-Seydima et al., 2004). Khadre and Yousef (2001) compared the effects of O3 and H2O2 against foodborne Bacillus spp. spores and found that O3 was more effective than H2O2. In shredded lettuce treated with O3, Kim et al. (1999) reported that bubbling O3 gas (49 mg/l, 0.5 l/min) in a lettuce-water mixture decreased the natural microbial load by 1.5–1.9 log unit cfu/g in 5 min. As a consequence, a number of patents have been issued for using O3 to treat fruit and vegetables. However, the results obtained by Singh et al. (2002) have shown that treatment with ozonated water (5.2 mg/l) did not result in any significant reduction in E. coli O157:H7 populations during 1–15 min of washing in shredded lettuce, although they found a reduction in microbial counts on baby carrots after 10 min exposure to 5.2 mg/l ozonated water. The reduced efficacy of ozonated water during lettuce washing might be due to more O3 demand of organic material in the medium as it was also found in melon fresh-cut pieces (Aguayo, 2003). It was shown that the use of O3 in the storage of vegetable products could have detrimental effects, as happened in some berries with very thin skin which can be easily penetrated by O3, oxidizing the fruit (Norton et al., 1968; Rice et al., 1982).The antimicrobial efficacy can be enhanced considerably when ozonation is combined with other chemical (e.g. H2O2) or physical (e.g. UV-C radiation) treatments. Mechanical action is also needed as a means to dislodge microorganisms from the surface of the food and expose them to the action of the sanitizer (Kim et al., 2003).6. Hot water treatmentsHeat preservation is one of the oldest forms of preservation known to man and has the potential to provide barriers to reduce microorganisms and inhibit enzyme activity, but this treatment is incompatible with fresh processed plant food since heat is associated with destruction of flavour, texture, colour and nutritional quality (Orsat et al., 2001). However, hot water treatments used to reduce or eliminate pathogens offer an alternative means to control the quality deterioration of fresh fruit and vegetables, as well as a means of enzyme inactivation (Bolin and Huxsoll, 1991). These mild heat treatments consist of subjecting the products to temperatures of 50–90°C for periods of time not exceeding 1–5 min. Loaiza-Velarde et al. (1997) reported that dipping lettuce in water at 45–55°C would extend the shelf-life and visual quality of minimally fresh processed lettuce by inhibiting the activity of PAL, which is the enzyme that initiates biosynthesis of phenolic compounds that leads to visible discoloration along the cut edge of the lettuce leaf (López-Gálvez et al., 1996). Additionally, Li et al. (2001) suggest that heat (50°C) treatment combined with 20 mg/l free chlorine for 90 smay have delayed browning and reduced initial populations of some groups of microorganisms naturally occurring on iceberg lettuce, but enhanced microbial growth during subsequent storage due to tissue damage.Delaquis et al. (1999, 2000) found a reduction of 2 log cfu/g in initial microbial load in lettuce washed with chlorinated water (100_l/l) at 47°C for 3 min, compared to washing at 4°C. However, in 2004, Delaquis et al. found that comparison between lettuce washed at 4°C and 50°C revealed that disinfection of the lettuce was improved by heat, although the difference in total microbial populations was only 1 log cfu/g.The application of mild heat treatments is commonly by using hot air, hot water or steam. Among them, hot water is the easiest conditioning treatment since it offers a great flexibility and easiest control(Barkai-Golan and Philips, 1991). However, Orsat et al. (2001) have demonstrated that it is possible to treat carrot sticks thermally with radio-frequency energy in less than 2 min at an internal temperature of 60°C, to reduce the microbial load before packaging while minimizing the detrimental effects on the sensory quality of the fresh-like product. The main difference in using this treatment is that in radio-frequency heating, the energy is absorbed directly within the material, the heating is rapid and uniform throughout the material and the technology is relatively simple to adapt to an existing processing line.保持微创新鲜已加工果蔬的微生物和感官质量的新兴技术（英文文献中文译稿）收获后水果对质量损失、生理病变、虫害等的保护的重点已经从使用农药转变为各种替代技术，包括生物控制、文化适应和物理方法如控制气氛、MAP和辐射。
水处理微生物学—细菌的遗传(中英文对照
局限性转导( restricted transduction)
Section E Bacterial genetics 细菌的遗传
E10 Transformation 转化
1.Overview（概述）
1.1 转化（transformation）：细菌能够从它们的周围环境中自然 吸收DNA，并将该片断掺入染色体基因组的现象称为转化。 1.2 20世纪20年代末期Fred Griffith发现这样一个现象： 1.3 在环境中基因自然转移，转化作用大概是一个重要的机制。
2.A typical phage life cycle（典型噬菌体的生活周期）
2.4 噬菌体装配（phage assembly）：一旦噬菌体的衣壳成分和核酸 被完全合成，新的噬菌体便自发组装。 2.5 释放（release）：噬菌体通过裂解细胞壁而释放，完成噬菌体 的一个生活周期，具有这种周期的噬菌体称为烈性噬菌体。噬菌 体用酶软化细胞壁，裂解细胞后释放出大约50~100个噬菌体；也 有的线性噬菌体穿过细胞壁后释放，并不损伤细胞。
Carbon cycle
图
Exercise
1. State the Carbon cycle in the earth. 2. State the Nitrogen cycle in the earth. 3. State the Sulfur cycle in the earth.
Section E Bacterial genetics 细菌的遗传
E9 Transduction 转导
1.Transduction（转导）
1.1 转导（transduction）：通过噬菌体颗粒的媒介，把一个细胞 的DNA转移到另一个细胞的机制称为转导. 1.2 转导现象在细菌和噬菌体中被广泛发现，在自然界遗传信息 的转移中起着显著的作用。转导在遗传学上也是一个重要的工具， 它可以用于细菌之间转移基因，也可以通过它绘制细菌染色体的 遗传图谱。
微生物翻译——精选推荐
Contributions of Microbes in Vertebrate Gastrointestinal Tract to Production and Conservation of Nutrients微生物在脊椎动物肠道中对生产和储存营养的贡献I.引言II.饮食，生活习性以及消化系统的总体特征的区别A 鱼类B 两栖类C 爬行类D 鸟类E 哺乳类Ⅲ化道和滞留时间Ⅳ肠道固有细菌的分布和特征A 反刍动物的前胃B 其他种类动物的前肠C 中肠D 后肠Ⅴ碳水化合物的发酵A 反刍动物的前胃B 其他种类动物的消化通道C 断链脂肪酸的吸收Ⅵ微生物蛋白的产生和氮循环A 反刍动物的前胃B 其他种类动物的前肠C 中肠D 胺的吸收和微生物所产生的氨基酸Ⅶ维生素是产生与吸收Ⅷ微生物的解毒作用Ⅸ与微生物发酵有关的疾病Ⅹ结论史蒂文斯,爱德华,伊恩d·休姆。
微生物在脊椎动物肠道中对生产和储存营养的贡献。
在脊椎动物的胃肠道内寄生的有细菌和一些能够将营养物与内源性物质转变为可吸收的营养成分的原生动物和真菌。
由于胃肠道具有一个中性的PH环境和较长的消化滞留时间，因此在哺乳动物，鸟类，爬行类和成熟的两栖类动物的后肠或大肠中，以及一些哺乳动物和至少一种鸟类的前肠中发现了最大的微生物种群。
细菌能够把碳水化合物发酵成为短链脂肪酸，把食物和内源性氮化合物转变为胺和微生物蛋白质，并能合成维生素B。
短链脂肪酸的吸收可以为肠上皮细胞提供能量，并在对钠和水的吸收过程中发挥着重要作用。
胺的吸收有助于氮和水的保持。
食草动物较大的肠道容量和较长的消化滞留时间为其提供了额外的短链脂肪酸，以用来维持能量，供微生物进行前肠发酵和后肠发酵合成蛋白质和维生素B。
原生动物和真菌也为寄主提供营养成分。
本文讨论了脊椎动物中常见的肠道微生物的贡献，由于食草动物具有许多的消化方式，从而使它们的这些贡献最大，同时其低纤维的食物和间隔的喂养影响着这些微生物的消化过程。
有关微生物的英语作文
有关微生物的英语作文英文回答：Microorganisms are a diverse group of organisms that include bacteria, viruses, fungi, and protozoa. They are found in all environments on Earth, from the deepest oceans to the highest mountains. Microorganisms play a vital role in the cycling of nutrients, the decomposition of organic matter, and the production of oxygen. They are also responsible for a wide range of human diseases, from the common cold to tuberculosis.The study of microorganisms is called microbiology. Microbiologists use a variety of techniques to study microorganisms, including microscopy, culturing, and molecular biology. Microscopy allows microbiologists to visualize microorganisms and study their morphology. Culturing allows microbiologists to grow microorganisms in the laboratory and study their growth and metabolism. Molecular biology allows microbiologists to study thegenetic material of microorganisms and understand how they function.Microorganisms have a wide range of applications in industry, medicine, and agriculture. In industry, microorganisms are used to produce a variety of products, including antibiotics, enzymes, and biofuels. In medicine, microorganisms are used to develop vaccines and antibiotics. In agriculture, microorganisms are used to improve soil fertility and crop yields.The study of microorganisms is essential for understanding the role they play in the environment and for developing new ways to use them to benefit humanity.中文回答：微生物是一个多样化的生物群，包括细菌、病毒、真菌和原生动物。
微生物学术语双语（中英文）对照
微生物学术语双语（中英文）对照Brock Biology of Microorganisms Bilingual Glossary（For Internal Circulation Only）微生物学术语双语（中英文）对照北京林业大学生物科学与技术学院微生物教研室谢响明2007年6月10日Catalogue目录Chapter1 Microorganisms and MicrobiologyChapter 2 An Overview of Microbial LifeChapter 3 MacromoleculesChapter 4 Cell Structure/FunctionChapter5 Nutrition, Laboratory Culture, and Metabolism of MicroorganismsChapter 6 Microbial GrowthChapter 7 Principles of Microbial Molecular Biology Chapter 8 Regulation of Gene ExpressionChapter 9 Essentials of VirologyChapter 10 Bacterial GeneticsChapter 11 Microbial Evolution and Systematics Chapter 15 Microbial GenomicsChapter 18 Methods in Microbial EcologyChapter 19 Microbial Habitats, Nutrients Cycles Chapter 20 Microbial Growth ControlBilingual Glossary for MicrobiologyChapter 1Landmark：里程碑Ramifications：分支non-cellular life ：非细胞生命prion：朊病毒microbial diversity and evolution：微生物的多样性和进化pathogens：病原体genetic engineering：基因工程entity：实体macromolecules：大分子Reproduction：繁殖Differentiation：分化Communication：信息沟通coding devices：编码机制attributes：特征，品质coordination.：协调regulation：调节optimally attuned to最适地调和populations：种群habitat.：生境assemblages：集合体microbial communities：微生物群落biofilms：生物被膜hot springs：温泉Aquatic：水生的Terrestrial：陆生的Prokaryotic cells：原核细胞ecosystem ：生态系统biomass：生物量nitrogen：氮phosphorus：磷Bubonic Plague：鼠疫Fleas：跳蚤Mortality：死亡率Grotesque：奇异Liquefy：液化Influenza and pneumonia：流感和肺炎Tuberculosis：肺结核spontaneous generation：自然发生学说microbes：微生物Broth：肉汤Flask：烧瓶Guncotton filters：棉花滤器Dissolved：溶解的Ether：醚Particles：微粒flask with swan neck：曲颈瓶sterilization：灭菌vaccines：疫苗anthrax：炭疽热fowl cholera：禽流感rabies：狂犬病Germ theory：病菌说Koch’s postulates：科赫假设(法则) contagious diseases：传染病artificially infected animals：人工感染的动物Solid medium：固体培养基Gelatin：明胶Agar：琼脂Colony formation：菌落形成Differential staining：鉴别染色Pure culture：纯培养isolation：分离, 隔离inoculation：接种Tuberculin：结核菌素Diagnosis：诊断Subdisciplines：（学科的）分支enrichment culture：富集培养aerobic：需氧的N-fixing bacteria：固氮细菌sulfate-reducing：硫酸盐还原sulfur-oxidizing bacteria：硫氧化细菌root nodule：根瘤Lactobacillus：乳酸杆菌tobacco mosaic virus：烟草花叶病毒tenets：原则virology：病毒学nitrifying bacteria：硝化细菌nitrification：硝化作用oxidation of ammonia to nitrate：从氨氧化为硝酸盐hydrogen sulfide：硫化氰chemolithotrophy：无机化能营养型autotrophs：自养生物anaerobe ：厌氧生物Clostridium pasteurianum：巴斯德羧菌属Medical microbiology and immunology：医学微生物学和免疫学Aquatic microbiology：水生微生物学Microbial ecology：微生物生态学Microbial systematic：微生物的系统学Microbial physiology：微生物生理学Cytology ：细胞学Bacterial genetics：细菌遗传学Chapter 2Evolutionary History：进化史Elements：原理，基础Viral Structure：病毒结构The Tree of Life：生命树Physiological：生理学的Eukaryotic：真核的Cytoplasmic (cell)membrane：细胞质膜Cytoplasm：细胞质Macromolecules：大分子Ribosome：核糖体organic molecules：有机分子inorganic ions：无机离子rod-shaped prokaryote：杆状原核生物organelles：细胞器Archaea：古生菌Nucleus：细胞核（nuclear的复数）Mitochondrion （Mitochondrion复数）线粒体Chloroplast：叶绿体Metazoans：后生生物Cytoplasmic：细胞质的Membrane：膜，隔膜Endoplasmic reticulum：内质网Nucleoid：类核，拟核Nucleolus：核仁Nuclear：核的，细胞核Static：静态的metabolic abilities：代谢能力biosynthetic：生物合成genetic alterations：遗传改造Genomes：基因组Chromosome：染色体Circular：环状copy：拷贝haploid：单倍体extrachromosomal：染色体外的。
微生物专业名词英文小作文
微生物专业名词英文小作文Microbes are fascinating creatures that exist all around us, from the air we breathe to the food we eat. They play a crucial role in our environment, both good and bad. Some microbes help us break down organic matter, while others can cause diseases.In the field of microbiology, scientists study these tiny organisms with great interest. They use special equipment like microscopes to observe them and understand their behavior. The diversity of microbes is incredible, from bacteria to viruses and fungi, each with unique characteristics and functions.One fascinating aspect of microbes is their resilience. They can survive in extreme conditions that would kill most other organisms. This adaptability allows them to thrive in places like the depths of the ocean or the harsh desert. And yet, despite their tiny size, they have a significant impact on our planet's ecosystems.Microbes are also essential for biotechnology and medical applications. They can be used to produce antibiotics and other useful compounds. In addition, researchers are exploring the potential of using microbes to clean up environmental pollution or even to develop new biofuels.Overall, microbes are fascinating and complex organisms that play a crucial role in our world. From the mundane to the cutting-edge, microbiology continues to be a vibrant and exciting field of study.。
杀菌、消毒 (微生物学) 英文版
Chemical agents V:
Chlorine 氯
reacts with water to form hypochlorite ions, which in turn denature microbial enzymes
Iodine碘 and iodophores
denatureve against some endospores
Denaturation of proteins Mercury汞 compounds (mercurochrome;
merthiolate) : bacteriostatic, ineffective against endospores Silver nitrate硝酸银 (1%) : dropped in the eyes of newborn babies to prevent gonococcal ophthalmia （淋球菌性结膜炎）.
The best way to preserve bacteria nowadays is lyophilization（冻干法）.
Section C Chemical Agents
Chemical agents I:
Phenol and phenol derivatives
Alteration of membrane permeability （膜渗透性） and denaturation of proteins
Disruption of cell membrane or wall
Removal of free sulfhydryl groups
DNA
-SH
-SS-
Chemical Antagonism
Protein denaturation
临床微生物细菌-英文版
Staphylococcus - facultatively anaerobic, grampositive, usually form irregular clusters, nonmotile, catalase positive but oxidase negative, ferment glucose anaerobically.
Rod-shaped
bacteria
Bacilli divide only across their short axis, so there are fewer groupings of bacilli than of cocci.
Single bacillus Diplobacilli streptobacilli
How to identify an unknown bacterial species ? The thousands of species of bacteria are differentiated by many factors, including morphology (shape), chemical composition (often detected by staining reactions), nutritional requirements, biochemical activities, and source of energy (sunlight or chemicals).
Micrococcus – aerobic, gram-positive, catalase positive, cell arranges mainly in pairs, tetrads, or irregular clusters, nonmotile. They are often yellow, orange or red in colour
- 1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。
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。