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Flsxx/测试
P. aeruginosa colonies on an agar plate.
科学分类
域： 细菌域 门： 变形菌门 纲： γ-变形菌纲 目： 假单胞菌目 科： 假单胞菌科 属： 假单胞菌属（Pseudonomas） Migula 1894
模式种
铜绿假单胞菌
种
铜绿假单胞菌组 P. aeruginosa（铜绿假单胞菌） P. alcaligenes（产碱假单胞菌） P. anguilliseptica（病鳝假单胞菌） P. argentinensis P. borbori P. citronellolis（香茅醇假单胞菌） P. flavescens（变黄假单胞菌） P. mendocina（多门萨假单胞菌） P. nitroreducens（硝基还原假单胞菌） P. oleovorans（食油假单胞菌） P. pseudoalcaligenes（类产碱假单胞菌） P. resinovorans（食树假单胞菌） P. straminea（稻草假单胞菌） 绿针假单胞菌组 P. agarici P. asplenii P. aurantiaca（桔黄假单胞菌） P. aureofaciens P. chlororaphis（绿针假单胞菌） P. corrugata P. fragi（霉实假单胞菌） P. lundensis（隆德假单胞菌） P. taetrolens（腐臭假单胞菌） 荧光假单胞菌组 P. antarctica P. azotoformans（产氮假单胞菌） P. blatchfordae P. brassicacearum P. brenneri P. cedrina P. corrugata（皱缩假单胞菌） P. fluorescens（荧光假单胞菌） P. gessardii P. libanensis P. mandelii P. marginalis（边缘假单胞菌） P. mediterranea P. meridiana P. migulae P. mucidolens（霉味假单胞菌） P. orientalis P. panacis P. protegens P. proteolytica P. rhodesiae（罗氏假单胞菌） P. synxantha（类黄假单胞菌） P. thivervalensis P. tolaasii（托氏假单胞菌） P. veronii（韦龙氏假单胞菌） 穿孔假单胞菌组 P. denitrificans（脱氮假单胞菌） P. pertucinogena（穿孔假单胞菌） 恶臭假单胞菌组 P. cremoricolorata P. fulva（黄褐假单胞菌） P. monteilii（蒙氏假单胞菌） P. mosselii P. oryzihabitans P. parafulva P. plecoglossicida P. putida（恶臭假单胞菌） 施氏假单胞菌组 P. balearica（巴利阿里假单胞菌） P. luteola P. stutzeri 丁香假单胞菌组 P. amygdali（扁桃假单胞菌） P. avellanae（榛色假单胞菌） P. caricapapayae（番木瓜假单胞菌） P. cichorii（菊苣假单胞菌）） P. coronafaciens P. ficuserectae（无花果假单胞菌） 'P. helianthi' P. meliae（苦楝假单胞菌） P. savastanoi（萨氏假单胞菌） P. syringae（丁香假单胞菌） P. tomato P. viridiflava（绿黄假单胞菌） 地位未定 P. abietaniphila P. acidophila P. agarici（伞菌假单胞菌） P. alcaliphila P. alkanolytica P. amyloderamosa P. asplenii（铁角蕨假单胞菌） P. azotifigens P. cannabina P. coenobios P. congelans P. costantinii P. cruciviae P. delhiensis P. excibis P. extremorientalis P. frederiksbergensis P. fuscovaginae（褐鞘假单胞菌） P. gelidicola（石花菜假单胞菌） P. grimontii P. indica P. jessenii P. jinjuensis P. kilonensis P. knackmussii P. koreensis P. lini P. lutea P. moraviensis P. otitidis P. pachastrellae P. palleroniana P. papaveris P. peli P. perolens P. poae P. pohangensis P. protegens P. psychrophila P. psychrotolerans P. rathonis P. reptilivora P. resiniphila P. rhizosphaerae P. rubescens P. salomonii P. segitis P. septica P. simiae P. suis P. thermotolerans P. toyotomiensis P. tremae P. trivialis P. turbinellae P. tuticorinensis P. umsongensis P. vancouverensis P. vranovensis P. xanthomarina

假单胞菌属（Pseudomonas）是假单胞菌科（Pseudomonadaceae）的一属，为一种革兰氏阴性菌。假单胞菌属广泛分布于土壤和水体中，在人体中亦有分布，多为化能有机营养型，某些种为兼性化能无机营养型，专性氧化（呼吸）代谢，所有种都以氧为最终电子受体，一些能以硝酸盐呼吸。细胞形态典型为极生鞭毛杆菌，体多呈现直或微弯的杆状，无菌柄及鞘，不产芽孢，许多种能够积累聚-β-羟基丁酸盐，作为储藏物质。大多数种能以单级毛或多级毛运动，进行呼吸性代谢，最终电子受体为氧，铜绿假单胞菌和个别情况下以硝酸盐为电子受体，进行厌氧呼吸，进行反硝化作用。一些种对植物及人畜具有致病性，如铜绿假单胞菌（P. aeruginosa）、鼻疽假单胞菌（P. mallei）和青枯病假单胞菌（P. solanacearum）等。直径约0.5至1微米，长约1至4微米。该属基因组DNA的GC比范围为58－69%。

该属的模式种为铜绿假单胞菌。目前临床上越来越多地将铜绿假单胞菌视作一种条件致病菌，几种不同的流行病学研究表明，其临床分离菌株的抗生素耐药性呈现上升趋势。

该属的种在代谢上表现出极大的多样性，因此能在多种生境下生长。由于该属的细菌易于进行体外培养，并且人们已经对该属下越来越多个种的基因组加以研究，假单胞菌属已经成为重要的科研对象，主要的有人体条件致病菌铜绿假单胞菌、植物致病菌丁香假单胞菌、土壤细菌恶臭假单胞菌和植物促生菌荧光假单胞菌等。

由于假单胞菌在水体及植物种子（如双子叶植物）上广泛分布，在微生物学领域已经早有研究。Walter Migula在1894年和1900年给“假单胞菌”这一属名的定义相当模糊，是指一种革兰氏阴性、棒状、极生鞭毛的细菌，一些种能产生孢子。但关于孢子的描述事后证明是错误的，这是一些储藏物质的折光性造成的误判。 Despite the vague description, the type species, Pseudomonas pyocyanea (basonym of Pseudomonas aeruginosa), proved the best descriptor.

分类历史

最初对假单胞菌进行分类是在19世纪末Walter Migula最早鉴别出该属的时候，至于这一名称的构词法，在当时并无明确说法，最早提到则在伯杰系统细菌学手册的第7版上，称是希腊语 ψευδες（pseudes，“假的”）和 μονάς / μονάδα（-monas，“单个”）；但也可能Migula的本意就是指“假的”滴虫（Monas，一种鞭毛虫类原生生物）。后来，monad一词在早期微生物学史上用于表示单细胞生物。不久以后，许多与Migula最初的模糊描述有或多或少匹配的物种被从各种生境中分离出来，在当时其中许多被分类到这个属。但是，后来人们用更新的分类学原则，并采用诸如保守生物大分子研究等更多手段，将其中一些物种重新分类归于其他属。

最近，16S rRNA的序列分析使得许多细菌的分类再次受到挑战。结果，金色单胞菌属（Chryseomonas）和黄色单胞菌属（Flavimonas）的种被并入假单胞菌属。一些原属于假单胞菌属的种被划分到伯克氏菌属（Burkholderia）及雷尔氏菌属（Ralstonia）。

2000年，人们得到了第一个假单胞菌属菌株的全基因组序列，近年来更多菌株的序列也测序完成，包括铜绿假单胞菌PAO1（2000年）、恶臭假单胞菌KT2440（2002年）、P. protegens Pf-5（2005年）、绿针假单胞菌GP72（2012年）等。

2008年在《科学美国人》（Scientific American）上发表的一篇文章表明，假单胞菌可能是云当中冰晶最常见的成核中心，可能说明假单胞菌对地球上雨和雪的形成起到了有极为重要的作用。

特征

假单胞菌属的种符合以下的定义性特征：

• 棒状；
• 革兰氏阴性；
• 单极或多极鞭毛，可运动；
• 好氧；
• 不产芽孢；
• 过氧化氢酶检测阳性；
• 氧化酶检测阳性。

也有其他一些仅能够判定可能属于假单胞菌属的特征（有例外），包括在环境铁含量不足的情况下分泌绿脓菌荧光素（pyoverdine，一种有荧光的黄绿色铁载体），一些特定的假单胞菌还能产生另一些铁载体，如铜绿假单胞菌代谢产生绿脓菌素，，或荧光假单胞菌代谢产生thioquinolobactin。

生物膜的形成

All species and strains of Pseudomonas are Gram-negative rods, and have historically been classified as strict aerobes. Exceptions to this classification have recently been discovered in Pseudomonas biofilms. A significant number of cells can produce exopolysaccharides which are associated with biofilm formation. Secretion of exopolysaccharide such as alginate, makes it difficult for pseudomonads to be phagocytosed by mammalian white blood cells. Exopolysaccharide production also contributes to surface-colonising biofilms which are difficult to remove from food preparation surfaces. Growth of pseudomonads on spoiling foods can generate a "fruity" odor.

Pseudomonas have the ability to metabolize a variety of nutrients. Combined with the ability to form biofilms, they are thus able to survive in a variety of unexpected places. For example, they have been found in areas where pharmaceuticals are prepared. A simple carbon source, such as soap residue or cap liner-adhesives is a suitable place for them to thrive. Other unlikely places where they have been found include antiseptics, such as quaternary ammonium compounds, and bottled mineral water.

Antibiotic resistance

Being Gram-negative bacteria, most Pseudomonas spp. are naturally resistant to penicillin and the majority of related beta-lactam antibiotics, but a number are sensitive to piperacillin, imipenem, ticarcillin, or ciprofloxacin. Aminoglycosides such as tobramycin, gentamicin, and amikacin are other choices for therapy.

This ability to thrive in harsh conditions is a result of their hardy cell wall that contains porins. Their resistance to most antibiotics is attributed to efflux pumps, which pump out some antibiotics before the antibiotics are able to act.

Pseudomonas aeruginosa is a highly relevant opportunistic human pathogen. One of the most worrying characteristics of P. aeruginosa is its low antibiotic susceptibility. This low susceptibility is attributable to a concerted action of multidrug efflux pumps with chromosomally encoded antibiotic resistance genes (e.g. mexAB-oprM, mexXY, etc.,) and the low permeability of the bacterial cellular envelopes. Besides intrinsic resistance, P. aeruginosa easily develops acquired resistance either by mutation in chromosomally encoded genes, or by the horizontal gene transfer of antibiotic resistance determinants. Development of multidrug resistance by P. aeruginosa isolates requires several different genetic events that include acquisition of different mutations and/or horizontal transfer of antibiotic resistance genes. Hypermutation favours the selection of mutation-driven antibiotic resistance in P. aeruginosa strains producing chronic infections, whereas the clustering of several different antibiotic resistance genes in integrons favours the concerted acquisition of antibiotic resistance determinants. Some recent studies have shown phenotypic resistance associated to biofilm formation or to the emergence of small-colony-variants may be important in the response of P. aeruginosa populations to antibiotic treatment.

Taxonomy

The studies on the taxonomy of this complicated genus groped their way in the dark while following the classical procedures developed for the description and identification of the organisms involved in sanitary bacteriology during the first decades of the 20th century. This situation sharply changed with the proposal to introduce as the central criterion the similarities in the composition and sequences of macromolecular components of the ribosomal RNA. The new methodology clearly showed the genus Pseudomonas, as classically defined, consisted in fact of a conglomerate of genera that could clearly be separated into five so-called rRNA homology groups. Moreover, the taxonomic studies suggested an approach that might prove useful in taxonomic studies of all other prokaryotic groups. A few decades after the proposal of the new genus Pseudomonas by Migula in 1894, the accumulation of species names assigned to the genus reached alarming proportions. At present, the number of species in the current list has contracted more than 90%. In fact, this approximated reduction may be even more dramatic if one considers the present list contains many new names, i.e., relatively few names of the original list survived in the process. The new methodology and the inclusion of approaches based on the studies of conservative macromolecules other than rRNA components, constitutes an effective prescription that helped to reduce Pseudomonas nomenclatural hypertrophy to a manageable size.

Pathogenicity

Animal pathogens

主条目：Pseudomonas infection

Infectious species include P. aeruginosa, P. oryzihabitans, and P. plecoglossicida. P. aeruginosa flourishes in hospital environments, and is a particular problem in this environment since it is the second most common infection in hospitalized patients (nosocomial infections). This pathogenesis may in part be due to the proteins secreted by P. aeruginosa. The bacterium possesses a wide range of secretion systems, which export numerous proteins relevant to the pathogenesis of clinical strains.

Plant pathogens

P. syringae is a prolific plant pathogen. It exists as over 50 different pathovars, many of which demonstrate a high degree of host plant specificity. There are numerous other Pseudomonas species that can act as plant pathogens, notably all of the other members of the P. syringae subgroup, but P. syringae is the most widespread and best studied.

Although not strictly a plant pathogen, P. tolaasii can be a major agricultural problem, as it can cause bacterial blotch of cultivated mushrooms. Similarly, P. agarici can cause drippy gill in cultivated mushrooms.

Use as biocontrol agents

Since the mid-1980s, certain members of the Pseudomonas genus have been applied to cereal seeds or applied directly to soils as a way of preventing the growth or establishment of crop pathogens. This practice is generically referred to as biocontrol. The biocontrol properties of P. fluorescens and P. protegens strains (CHA0 or Pf-5 for example) are currently best understood, although it is not clear exactly how the plant growth-promoting properties of P. fluorescens are achieved. Theories include: that the bacteria might induce systemic resistance in the host plant, so it can better resist attack by a true pathogen; the bacteria might out compete other (pathogenic) soil microbes, e.g. by siderophores giving a competitive advantage at scavenging for iron; the bacteria might produce compounds antagonistic to other soil microbes, such as phenazine-type antibiotics or hydrogen cyanide. There is experimental evidence to support all of these theories.

Other notable Pseudomonas species with biocontrol properties include P. chlororaphis, which produces a phenazine-type antibiotic active agent against certain fungal plant pathogens, and the closely related species P. aurantiaca which produces di-2,4-diacetylfluoroglucylmethane, a compound antibiotically active against Gram-positive organisms.

Use as bioremediation agents

Some members of the genus Pseudomonas are able to metabolise chemical pollutants in the environment, and as a result can be used for bioremediation. Notable species demonstrated as suitable for use as bioremediation agents include:

• P. alcaligenes, which can degrade polycyclic aromatic hydrocarbons.
• P. mendocina, which is able to degrade toluene.
• P. pseudoalcaligenes is able to use cyanide as a nitrogen source.
• P. resinovorans can degrade carbazole.
• P. veronii has been shown to degrade a variety of simple aromatic organic compounds.
• P. putida has the ability to degrade organic solvents such as toluene. At least one strain of this bacterium is able to convert morphine in aqueous solution into the stronger and somewhat expensive to manufacture drug hydromorphone (Dilaudid).
• Strain KC of P. stutzeri is able to degrade carbon tetrachloride.

Food spoilage agents

As a result of their metabolic diversity, ability to grow at low temperatures and ubiquitous nature, many Pseudomonas spp. can cause food spoilage. Notable examples include dairy spoilage by P. fragi, mustiness in eggs caused by P. taetrolens and P. mudicolens, and P. lundensis, which causes spoilage of milk, cheese, meat, and fish.

Species previously classified in the genus

Recently, 16S rRNA sequence analysis redefined the taxonomy of many bacterial species previously classified as being in the Pseudomonas genus. Species which moved from the Pseudomonas genus are listed below; clicking on a species will show its new classification. Note that the term 'pseudomonad' does not apply strictly to just the Pseudomonas genus, and can be used to also include previous members such as the genera Burkholderia and Ralstonia.

α proteobacteria: P. abikonensis, P. aminovorans, P. azotocolligans, P. carboxydohydrogena, P. carboxidovorans, P. compransoris, P. diminuta, P. echinoides, P. extorquens, P. lindneri, P. mesophilica, P. paucimobilis, P. radiora, P. rhodos, P. riboflavina, P. rosea, P. vesicularis.

β proteobacteria: P. acidovorans, P. alliicola, P. antimicrobica, P. avenae, P. butanovorae, P. caryophylli, P. cattleyae, P. cepacia, P. cocovenenans, P. delafieldii, P. facilis, P. flava, P. gladioli, P. glathei, P. glumae, P. graminis, P. huttiensis, P. indigofera, P. lanceolata, P. lemoignei, P. mallei, P. mephitica, P. mixta, P. palleronii, P. phenazinium, P. pickettii, P. plantarii, P. pseudoflava, P. pseudomallei, P. pyrrocinia, P. rubrilineans, P. rubrisubalbicans, P. saccharophila, P. solanacearum, P. spinosa, P. syzygii, P. taeniospiralis, P. terrigena, P. testosteroni.

γ-β proteobacteria: P. beteli, P. boreopolis, P. cissicola, P. geniculata, P. hibiscicola, P. maltophilia, P. pictorum.

γ proteobacteria: P. beijerinckii, P. diminuta, P. doudoroffii, P. elongata, P. flectens, P. halodurans, P. halophila, P. iners, P. marina, P. nautica, P. nigrifaciens, P. pavonacea, P. piscicida, P. stanieri.

δ proteobacteria: P. formicans.

Bacteriophage

There are a number of bacteriophage that infect Pseudomonas, e.g.

• Pseudomonas phage Φ6
• Pseudomonas aeruginosa phage EL
• Pseudomonas aeruginosa phage ΦKMV
• Pseudomonas aeruginosa phage LKD16
• Pseudomonas aeruginosa phage LKA1
• Pseudomonas aeruginosa phage LUZ19
• Pseudomonas aeruginosa phage ΦKZ

See also

• culture collection for a list of culture collections

External links

General

• Pseudomonas at origin of world's rain and snow
• Pseudomonas survive in nuclear reactor
• Pseudomonas genome database
• Pseudomonas
• Fluorescent Pseudomonas video