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Xanthomonas campestris és una espècie de bacteri que d'una banda causa una gran varietat de malalties a les plantes i de l'altra banda, en la seva forma purificada, es fa servir per produir el polisacàrid goma xantana utilitzada a la indústria alimentària i amb altres usos.
(pv. significa patovar, una classificació segons l'hoste de planta atacada per Xanthomonas campestris)
El pv. citri, que causa el xancre dels cítrics, es va reclassificar com X. axonopodis el 1995 Xanthomonas campestris#cite note-0. El 2006, per pv. citri i malvacearum va ser revisat a X. citri i aquests patovars s'anomenen com la subespècie[1]
Xanthomonas campestris és una espècie de bacteri que d'una banda causa una gran varietat de malalties a les plantes i de l'altra banda, en la seva forma purificada, es fa servir per produir el polisacàrid goma xantana utilitzada a la indústria alimentària i amb altres usos.
Xanthomonas campestris is a gram-negative, obligate aerobic bacterium that is a member of the Xanthomonas genus, which is a group of bacteria that are commonly known for their association with plant disease.[1] The species is considered to be dominant amongst its genus, as it originally had over 140 identified pathovars and has been found to infect both monocotyledonous and dicotyledonous plants of economical value with various plant diseases.[1] This includes "black rot" in cruciferous vegetables, bacterial wilt of turfgrass, bacterial blight, and leaf spot, for example. [2][3][4]
These bacteria are facultative saprophytes, meaning that they are typically parasitic while also having the ability to live on dead or decaying organic matter under the proper conditions. Upon initial infection, the bacteria remain in the epiphytic stage; however, the harmful endophytic stage is reached when the bacteria actually enter the plant host through natural openings.[4] In general, the genes that contribute significantly to the plant-bacteria relationship are the avirulence (avr) genes, the hypersensitivity response and pathogenicity (hrp) genes, and the pathogenicity factors (rpf) genes.[1][2][5] Additionally, the virulence determinants associated with the seedborne diseases that result from this bacterium include extracellular enzymes, polysaccharides, lipopolysaccharides, etc.[2]
Several strains of Xanthomonas campestris also produce an exopolysaccharide called xanthan, making it valuable in the commercial production of xanthan gum, which has important uses in the food, oil, agricultural, and pharmaceutical industries.[6]
There have been over 140 pathovars of Xanthomonas campestris that have been identified, and they are typically named according to the plant that they were first found to infect.[1] However, upon further investigation of genetic relationships, many of these pathovars are now being reclassified as different species within the Xanthomonas genus instead.[1] This leaves six pathovars of Xanthomonas campestris remaining, which includes Xanthomonas campestris pv. abberans, Xanthomonas campestris pv. armoraciae, Xanthomonas campestris pv. barbarreae, Xanthomonas campestris pv. campestris, Xanthomonas campestris pv. incanae, and Xanthomonas campestris pv. raphani.[3]
Further investigation of pathogenicity profiles and multilocus sequencing typing suggests that the list should actually be further narrowed down to just three pathovars with the different symptoms being black rot, leaf spot, and bacterial blight.[3] That said, Xanthomonas campestris pv. campestris is commonly known for causing black rot of crucifers, and Xanthomonas campestris pv. incanae has the ability to impact ornamental brassica plants through bacterial blight. Both of these pathovars are vascular pathogens, and they have been found to invade the plant host through wounds or hydathodes. Alternatively, Xanthomonas campestris pv. campestris also has the ability to infect the plant host through the stomata. Xanthomonas pv. raphani has been found to enter the plant through its stomata to cause infection of the tissue, or rather parenchyma. This results in bacterial spot on a wider range of hosts, which includes both crucifers and certain solanaceous plants.[1][3]
Relationships between Xanthomonas campestris bacteria and plants can be both compatible and incompatible. It is in the compatible relationships, where the bacteria are able to overcome the host's defenses, rather than experience attenuated growth, that disease symptoms will be seen in the plants.[2] This is due to toxins, extracellular enzymes (exported by the type II secretion system), polysaccharides, lipopolysaccharides, a fatty acid-dependent cell-cell communication system, and proteins (secreted by the type III secretion system), for example.[1] The genes in the bacterial genome that are responsible for such interactions include avirulence (avr) and hypersensitivity response and pathogenicity (hrp) genes.[2]
Gene-for-gene patterns control the interactions between the Xanthomonas campestris, a bacterial pathogen, and plants. Avr genes are a group of genes that impact the specificity of the interaction between the bacteria and the plant host. When either these bacterial genes or a plant's resistance genes to the pathogen are not present, the interaction will result in disease. Alternatively, when the genes are present, the plant's resistance genes will produce a product that is able to recognize the avr genes of the bacteria, which allows for the plant host to have resistance.[2] Hrp genes are responsible for the determination of the outcome of the interaction between the plant and bacteria. When mutation occurs within these genes, there is impact on both compatible and incompatible interactions. This is the case because there may be an impact on pathogenicity and hypersensitivity response, respectively.[2] Therefore, the plant's ability to limit the spread of the microbial pathogen may be inhibited.
The regulation of pathogenicity factors (rpf) gene cluster also plays an important role in the plant-bacteria interactions by encoding for a cell-cell signaling system involving diffusible signal factor that is necessary for full virulence. This regulation system is involved in the regulation of both the formation and dispersal of Xanthomonas campestris biofilms, which is specifically related to the rpfB and rpfF genes within the cluster.[1][5] With a mutation in the rpf genes, the synthesis of various extracellular enzymes will be downregulated. This includes endoglucanase, protease, and extracellular polysaccharide (EPS) xanthan, for example, which are important to the virulence of the bacteria.[5]
Like with Xanthomonas species in general, the primary route of transmission for Xanthomonas campestris is through seeds, which act as the source of inoculum.[2][4] Therefore, the bacteria are initially in the epiphytic stage of the infection cycle, which is when they grow on the surface of the plant, such as on the aerial tissues of leaves and fruit. Various adhesion strategies are utilized by the microbes in order to remain attached to the plant surfaces, and this includes bacterial surface polysaccharides, adhesion proteins, and type IV pili.[4] Then, biofilm matrices composed primarily of xanthan will form, which will help the bacteria to survive in the harsh abiotic conditions of the plant surfaces. These biofilms, along with pigments, also help the bacteria to survive the potential damages to DNA and membrane that result from radiation and light. Eventually, the bacteria enter the host tissue through natural openings such as pores and stomata, or wounds, which is hypothesized to be a result of chemotaxis.[4] When this happens, the endophytic stage has been reached and colonization in the vascular system or parenchyma takes place. This is when the development of symptoms, such as lesions of leaves, will occur.[4] Progression into the stem and roots can eventually happen as well, which is when there is systematic infection of the plant. Furthermore, Xanthomonas campestris can be spread to other plants when the population of bacteria has increased enough that they emerge on the plant surfaces again. This dispersal includes both environmental and mechanical routes, such as through wind, rain, people, non-specific vectors, seed dispersal, etc.[4]
Xanthomonas campestris is commonly used industrially to produce a water-soluble exo-polysaccharide, known as xanthan gum, from fermentation of carbon sources like glucose.[6] In this process, a preserved culture of the gram-negative bacterium is expanded through growth and then used as an inoculum in bioreactors with liquid growth media. Under select modes of operation, such as batch fermentation, and proper growth conditions, fermentation then takes place. Therefore, as the microorganism grows, there is production of xanthan, which is secreted from the bacterial cells and ultimately recovered from the media and purified using alcohol precipitation techniques.[6]
This product is particularly applicable to the food industry as a suspending, thickening, and stabilizing agent. However, it also has applications pertaining to the agricultural industry, the oil industry, the pharmaceutical industry, etc.[6] Because of that, work is being done to investigate advancements that can be made to the current xanthan gum production processes.
Xanthomonas campestris is a gram-negative, obligate aerobic bacterium that is a member of the Xanthomonas genus, which is a group of bacteria that are commonly known for their association with plant disease. The species is considered to be dominant amongst its genus, as it originally had over 140 identified pathovars and has been found to infect both monocotyledonous and dicotyledonous plants of economical value with various plant diseases. This includes "black rot" in cruciferous vegetables, bacterial wilt of turfgrass, bacterial blight, and leaf spot, for example.
These bacteria are facultative saprophytes, meaning that they are typically parasitic while also having the ability to live on dead or decaying organic matter under the proper conditions. Upon initial infection, the bacteria remain in the epiphytic stage; however, the harmful endophytic stage is reached when the bacteria actually enter the plant host through natural openings. In general, the genes that contribute significantly to the plant-bacteria relationship are the avirulence (avr) genes, the hypersensitivity response and pathogenicity (hrp) genes, and the pathogenicity factors (rpf) genes. Additionally, the virulence determinants associated with the seedborne diseases that result from this bacterium include extracellular enzymes, polysaccharides, lipopolysaccharides, etc.
Several strains of Xanthomonas campestris also produce an exopolysaccharide called xanthan, making it valuable in the commercial production of xanthan gum, which has important uses in the food, oil, agricultural, and pharmaceutical industries.
Xanthomonas campestris es una bacteria que causa una variedad de fitopatologías. Es usada en la producción comercial de un polisacárido de alto peso molecular, la goma xantana, que es un eficiente viscosificador de soluciones acuosas, con importantes usos, especialmente en la industria alimenticia.
Datos: Q3753551
Multimedia:
Especies: Xanthomonas campestris
Xanthomonas campestris est une espèce de Protéobacteries de la famille des Xanthomonadaceae.
Cette bactérie phytopathogène est responsable de diverses maladies des plantes.
Elle est utilisée dans la production commerciale d'un polysaccharide à haut poids moléculaire, la gomme de xanthane, qui est un agent efficace de viscosité de l'eau et qui a de nombreuses utilisations importantes, en particulier dans l'industrie alimentaire. Elle est disponible dans une forme purifiée auprès de diverses collections internationales de microorganismes, telles que la National Collection of Plant Pathogenic Bacteria (NCPPB, Royaume-Uni) , l’International collection of microorganisms from plants (ICMP, Nouvelle-Zélande), l’American Type Culture Collection (ATCC, États-Unis), la Collection française de bactéries associées aux plantes (CFBP) ou la collection de bactéries BCCM/LMG (Belgique).
Selon NCBI (14 juin 2014)[2] :
Xanthomonas campestris est une espèce de Protéobacteries de la famille des Xanthomonadaceae.
Cette bactérie phytopathogène est responsable de diverses maladies des plantes.
Elle est utilisée dans la production commerciale d'un polysaccharide à haut poids moléculaire, la gomme de xanthane, qui est un agent efficace de viscosité de l'eau et qui a de nombreuses utilisations importantes, en particulier dans l'industrie alimentaire. Elle est disponible dans une forme purifiée auprès de diverses collections internationales de microorganismes, telles que la National Collection of Plant Pathogenic Bacteria (NCPPB, Royaume-Uni) , l’International collection of microorganisms from plants (ICMP, Nouvelle-Zélande), l’American Type Culture Collection (ATCC, États-Unis), la Collection française de bactéries associées aux plantes (CFBP) ou la collection de bactéries BCCM/LMG (Belgique).
Xanthomonas campestris é unha especie de bacteria que por unha banda causa unha gran variedade de doenzas nas plantas e pola outra, na súa forma purificada, utilízase para producir o polisacárido goma xantana utilizado na industria alimentaria como estabilizante, espesante e emulsificante; e con outros usos.
(pv. significa patovar, unha clasificación segundo o hóspede de planta atacada por Xanthomonas campestris)
O pv. citri, que causa o cancro cítrico, reclasificouse coma X. axonopodis en 1995 Xanthomonas campestris#cite note-0. En 2006, por pv. citri e malvacearum foi revisado en X. citri e estes patovares chámanse coma a subespecie[1].
Xanthomonas campestris é unha especie de bacteria que por unha banda causa unha gran variedade de doenzas nas plantas e pola outra, na súa forma purificada, utilízase para producir o polisacárido goma xantana utilizado na industria alimentaria como estabilizante, espesante e emulsificante; e con outros usos.
Xanthomonas campestris is een bacteriesoort, die verschillende plantenziektes kan veroorzaken. Xanthomonas campestris wordt gebruikt om Xanthaangom te maken.
De classificatie is gebaseerd is op de plant die wordt aangetast door Xanthomonas campestris. pv. staat voor pathovar.
Xanthomonas campestris is een bacteriesoort, die verschillende plantenziektes kan veroorzaken. Xanthomonas campestris wordt gebruikt om Xanthaangom te maken.
Predominantemente com geração isolada, a bactéria Xanthomonas campestris e suas variações recebem a denominação de gram-negativas e possuem morfologia semelhante a bastonetes.[1]
Este tipo de bactéria, junto as suas diferentes espécies, possuem a capacidade de confeccionar através de fermentação o polissacarídeo Goma Xantana quando introduzido em meio contendo fontes de carbono, nitrogênio, fósforo junto a outros micronutrientes, possuindo um grande valor agregado visto as suas características reológicas. Pode ser maximizado com um consequente meio fermentativo com dosagens específicas de nutrientes e o respectivo controle de parâmetros como temperatura, pH, pressão, entre outros, que promovem melhor adaptação da variedade do microrganismo no meio selecionado.[2]
Predominantemente com geração isolada, a bactéria Xanthomonas campestris e suas variações recebem a denominação de gram-negativas e possuem morfologia semelhante a bastonetes.
Xanthomonas campestris är en bakterie bland pseudomonaderna, stavformig med polär cilie.
Den förekommor allmänt i blad, stjälk och rot hos korsblommiga växter som olika slags kål, kålrötter, rovor med flera. De infekterar värdväxterna brunbakterios, som brunfärgar växtens kärlsträngar med omgivande delar. Används för kommersiell framställning av Xantangummi som bl.a. används som förtjockningsmedel inom livsmedelsindustrin.
Xanthomonas campestris är en bakterie bland pseudomonaderna, stavformig med polär cilie.
Den förekommor allmänt i blad, stjälk och rot hos korsblommiga växter som olika slags kål, kålrötter, rovor med flera. De infekterar värdväxterna brunbakterios, som brunfärgar växtens kärlsträngar med omgivande delar. Används för kommersiell framställning av Xantangummi som bl.a. används som förtjockningsmedel inom livsmedelsindustrin.
カンキツかいよう病（かんきつかいようびょう）はカンキツかいよう病菌（Xanthomonas campestris pv. citri）により引き起こされる柑橘類の病気で、世界の栽培地で広く発生している、柑橘における最重要病害のひとつである。果実、葉、枝などに発生し、被害果実の商品価値を低下させて、多発すると落葉や枝枯れ、樹勢の著しい低下を招く場合もある[1][2][3]。
果実、葉、枝に褐色の病斑を形成する。病斑は最初盛り上がった濃緑色の水浸状円形で、拡大するとともに頂部にザクロ状の亀裂を生じて、中央部から次第にコルク化する。葉が成熟する頃には直径2~5mm程度となり、病斑の周縁は幅1~2mmが黄色になる。春葉の展開開始期から発病し、その伝染源は越冬病斑である。病原菌は雨によって飛散し、さらに感染を広げる。病原菌の侵入は、伸長・肥大期には主として気孔からで、初夏以降は風やミカンハモグリガなどによってできた傷口から侵入する[2][3]。
カンキツかいよう病菌は、短桿状の細菌で大きさは1.5~2.0×0.5~0.75μm。1本の鞭毛を有する。好気性でグラム陰性、発病適温は20~30℃である[3]。
この項目は、植物に関連した書きかけの項目です。この項目を加筆・訂正などしてくださる協力者を求めています（プロジェクト:植物／Portal:植物）。 カンキツかいよう病（かんきつかいようびょう）はカンキツかいよう病菌（Xanthomonas campestris pv. citri）により引き起こされる柑橘類の病気で、世界の栽培地で広く発生している、柑橘における最重要病害のひとつである。果実、葉、枝などに発生し、被害果実の商品価値を低下させて、多発すると落葉や枝枯れ、樹勢の著しい低下を招く場合もある。
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