Name: antibiotic resistance in cloning
Uploaded: 2026-08-26T08:20:54.022Z
Duration: 1 min 45 s
Channel: JoVE

K12 Standards

Louisiana Student Standards for Science

High School

Life Sciences

from-molecules-to-organisms-structures-and-processes

From Molecules To Organisms: Structures And Processes

HS-LS1-8

Antibiotic Selection

Die Antibiotika-Selektion wird normalerweise verwendet, um sicherzustellen, dass eine Bakterienkolonie ein Plasmid mit einigen Schl&#xFC;sselmerkmalen enth&#xE4;lt.
 Ein Antibiotikaresistenzgen und ein Gen von Interesse, mit dem ein Forscher exprimieren m&#xF6;chte.
 Damit die Bakterien das Plasmid aufnehmen k&#xF6;nnen, m&#xFC;ssen beide zusammen inkubiert und dann einem Hitzeschock unterzogen werden, um die Vebindung zu f&#xF6;rdern.
 Nicht jedes Bakterium nimmt erfolgreich eine Kopie des Plasmids auf.
 Ziel ist es, Bakterien zu isolieren, die eine Kopie besitzen.
 Forscher geben einen Teil der Bakterienkultur auf eine Platte, die ein Antibiotikum enth&#xE4;lt.
 Nur die Bakterien, die das Plasmid aufgenommen haben, das das Resistenzgen enth&#xE4;lt, k&#xF6;nnen das Antibiotikum abbauen und auf der Platte wachsen.
 In den n&#xE4;chsten Tagen bilden einzelne Bakterien Kolonien, die f&#xFC;r die weitere Arbeit ausgew&#xE4;hlt werden k&#xF6;nnen.

Courvalin, P. 2016. "Warum ist Antibiotikaresistenz eine tödlich auftretende Krankheit?" Klinische Mikrobiologie und Infektion 22 (5): 405–7. [<a href="https://doi.org/10.1016/j.cmi.2016.01.012" target="__blank">Quelltext</a>]

Daubin, Vincent und Gergely J. Szöllősi. 2016. "Horizontaler Gentransfer und die Geschichte des Lebens." Cold Spring Harbor: Perspektiven in der Biologie 8 (4). [<a href="https://doi.org/10.1101/cshperspect.a018036" target="__blank">Quelle</a>]

Hiltunen, Teppo, Marko Virta und Anna-Liisa Laine. 2017. "Antibiotikaresistenz in freier Wildbahn: Eine öko-evolutionäre Perspektive." Philosophical Transactions of the Royal Society B: Biological Sciences 372 (1712). [<a href="https://doi.org/10.1098/rstb.2016.0039" target="__blank">Quelltext</a>]

antibiotische selektion

<h4>&#xDC;berblick</h4>
 
 Forscher verwenden Antibiotikaresistenz-Gene, um Bakterien zu identifizieren, die ein Plasmid mit dem zu untersuchenden Gen enthalten. Die Antibiotikaresistenz kommt auch nat&#xFC;rlich vor, wenn eine spontane DNA-Mutation Ver&#xE4;nderungen in Bakteriengenen, welche die antibiotische Wirkung ausschalten, hervorruft. Bakterien k&#xF6;nnen diese neuen Resistenzgene mit ihren Nachkommen und anderen Bakterien teilen. Der &#xFC;berm&#xE4;&#xDF;ige Einsatz und Missbrauch von Antibiotika hat zu einer Krise in der &#xF6;ffentlichen Gesundheit gef&#xFC;hrt, da sich vermehrt resistente und multiresistente Bakterien entwickeln.
 
 <h4>Die Antibiotikaresistenz ist ein notwendiges Werkzeug in der Gentechnik</h4>
 
 Antibiotika, wie z.B. Penicillin, sind Medikamente, die Bakterien t&#xF6;ten oder ihr Wachstum stoppen k&#xF6;nnen. Bakterien, die eine nat&#xFC;rliche oder k&#xFC;nstlich erzeugte Antibiotikaresistenz haben, reagieren nicht auf Antibiotika. Wissenschaftler nutzen dies, um Plasmide zu entwerfen, die sowohl ein Antibiotikum-Resistenzgen als auch das von ihnen zu untersuchende Gen enth&#xE4;lt. Plasmide sind kleine, sich selbst replizierende DNA-St&#xFC;cke. Die Antibiotikaresistenz ist ein integraler Bestandteil der Klonierung, die es einem Forscher erm&#xF6;glicht, Zellen zu identifizieren, die das zu untersuchende Gen aufgenommen haben.
 
 Das gew&#xFC;nschte DNA-St&#xFC;ck wird dann in bakterielle Zellen in einem Prozess, der Transformation, eingef&#xFC;hrt. Bei der bakteriellen Transformation werden vor&#xFC;bergehend kleine L&#xF6;cher in der bakteriellen Zellwand erzeugt, die die Aufnahme von externer DNA, wie z.B. ein Plasmid, erm&#xF6;glichen. Nur einige Bakterienzellen nehmen neue DNA auf. Da das Plasmid, dass gew&#xFC;nschte DNA-St&#xFC;ck sowie ein Gen, das die Resistenz gegen ein spezifisches Antibiotikum enth&#xE4;lt, kann ein Antibiotikum nun angewendet werden um festzustellen welche Bakterienzellen genetisch ver&#xE4;ndert wurden. Dieser Prozess wird auch antibiotische Selektion genannt.
 
 Der Forscher verteilt die Bakterienzellen in einer Petrischale auf einem N&#xE4;hrboden, der das ausgew&#xE4;hlte Antibiotikum enth&#xE4;lt. Nur Bakterien, die das Antibiotikum-Resistenzgen enthalten, &#xFC;berleben und wachsen. Nach einem Tag kann der Forscher eine Bakterienkolonie ausw&#xE4;hlen, die er f&#xFC;r weitere Experimente, wie Genexpressions-Studien, kultivieren kann. Nach der Selektion mit dem Antibiotikum, testet der Forscher die Bakterien mit zus&#xE4;tzlichen Methoden (z.B. PCR), um zu best&#xE4;tigen, dass das gew&#xFC;nschte DNA-St&#xFC;ck tats&#xE4;chlich enthalten ist. Das ist notwendig, da in diesem Prozess h&#xE4;ufig Fehler auftreten, wie zum Beispiel, dass das Plasmid das gew&#xFC;nschte Gen gar nicht enth&#xE4;lt.
 
 <h4>Bakterien k&#xF6;nnen Antibiotikaresistenzen nat&#xFC;rlich bekommen</h4>
 
 Bakterien k&#xF6;nnen eine Antibiotikaresistenz erwerben durch spontane DNA-Mutationen, die die von der Zelle produzierten Proteine ver&#xE4;ndern. Widerstandsf&#xE4;hige Bakterien k&#xF6;nnen Proteine produzieren, die dazu f&#xFC;hren, dass das Antibiotikum abgebaut wird, aus der Zelle herausgepumpt wird oder sie verhindern die Interaktion mit seinem Zielprotein. So hemmt das Antibiotikum Vancomycin beispielsweise die Synthese der bakteriellen Zellwand. Einige Bakterien haben eine Resistenz gegen dieses Antibiotikum entwickelt, indem sie die Protein-Untereinheiten (Aminos&#xE4;uren), die beim Aufbau ihrer Zellwand notwendig sind gegen solche ausgetauscht, die nicht von Vancomycin beeinflusst werden.
 
 Sobald Antibiotikum-Resistenzgene entstehen, k&#xF6;nnen Bakterien diese an ihre Nachkommen weitergeben. Bakterien k&#xF6;nnen auch Antibiotikum-Resistenzgene von anderen Bakterien der gleichen oder anderer Spezies durch einen Prozess erwerben, der als horizontaler Gentransfer (HGT) bezeichnet wird. Es gibt drei Mechanismen des HGT: Transformation, Konjugation und Transduktion. Antibiotikum-Resistenzgene finden sich h&#xE4;ufig in Plasmiden oder Transposons, das sind DNA-St&#xFC;cke, die leicht zwischen Bakterien &#xFC;bertragen werden und w&#xE4;hrend des HGTs ausgetauscht werden. Infolgedessen k&#xF6;nnen sich neue Typen von Antibiotikaresistenzen schnell auf mehrere Arten von infekti&#xF6;sen Bakterien &#xFC;bertragen.
 
 <h4>Klinische &#xDC;ber- und Fehlanwendung von Antibiotika produziert &#x201C;Superbakterien&#x201D;</h4>
 
 Antibiotika sind f&#xFC;r die Behandlung bakterieller Infektionen von entscheidender Bedeutung. Ihr Einsatz kann jedoch dazu f&#xFC;hren, dass Bakterien resistent werden und das Antibiotikum unwirksam wird. Das f&#xFC;hrt zu nicht-behandelbaren und potenziell t&#xF6;dlichen Infektionen. Die &#xFC;berm&#xE4;&#xDF;ige Anwendung und der der Missbrauch von Antibiotika ist problematisch, da es zu Resistenzen f&#xFC;hrt, wie zum Beispiel bei der Verwendung von Antibiotika zur Behandlung von viralen (statt bakteriellen) Infektionen oder zur Wachstumsbeschleunigung bei Nutztieren.
 
 Antibiotika verursachen die Entwicklung von Resistenzen, weil anf&#xE4;llige Bakterien get&#xF6;tet werden und nur widerstandsf&#xE4;hige Individuen &#xFC;berleben. Die &#xFC;berlebenden Bakterien teilen sich schnell und produzieren Nachkommen mit der gleichen Antibiotikaresistenz. Bei &#xFC;berm&#xE4;&#xDF;igem Einsatz von Antibiotika f&#xFC;hrt dieser Selektionsdruck dazu, dass die Zahl der resistenten Bakterien in der Bev&#xF6;lkerung schnell ansteigt. Dies stellt f&#xFC;r die &#xF6;ffentliche Gesundheit ein gro&#xDF;es Problem dar, da vermehrt Antibiotikaresistenzen auftreten und &#x201C;Superbakterien&#x201D; geschaffen werden. Das sind Bakterien, die gegen mehrere Antibiotika resistent sind. Der anhaltende und &#xFC;berm&#xE4;&#xDF;ige Einsatz sowie der Missbrauch von Antibiotika kann schlie&#xDF;lich zu einer Ersch&#xF6;pfung der Behandlungsm&#xF6;glichkeiten f&#xFC;r bakterielle Infektionen f&#xFC;hren.

Antibiotische Selektion

Overview

Researchers use antibiotic resistance genes to identify bacteria that possess a plasmid containing their gene of interest. Antibiotic resistance ...

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antibiotic resistance in cloning

Antibiotic resistance genes help scientists find bacteria that took up a plasmid with a gene of interest. In genetic engineering, this resistance is used as a marker, not just as a medical concern. The same process also connects to the growing problem of resistant bacteria in the real world.

Antibiotics, such as penicillin, stop bacterial growth or kill bacteria. When bacteria naturally have, or are engineered to carry, an antibiotic resistance gene, the antibiotic no longer works on them. Researchers build plasmids, which are small pieces of self-replicating DNA, with both the gene of interest and a resistance gene. This makes antibiotic resistance an important part of DNA cloning and cell selection.

To move DNA into bacteria, scientists use transformation. During transformation, small holes are made in the bacterial cell wall so external DNA, like a plasmid, can enter. Only some cells take up the new DNA. Scientists then place the bacteria on a plate containing the chosen antibiotic. Only cells with the resistance gene survive and form colonies.

After a few days, a colony can be picked and grown for later experiments, such as gene expression studies. The bacteria are often tested again with methods like PCR to confirm that the DNA of interest is correct. This step matters because mistakes can happen, including plasmids that do not contain the target gene at all.

Bacteria can also gain antibiotic resistance naturally through spontaneous DNA mutations. These changes may produce proteins that break down the antibiotic, pump it out of the cell, or block it from reaching its target. For example, vancomycin blocks bacterial cell wall synthesis, but some bacteria avoid its effect by changing the amino acid subunits used to build their cell wall.

Once resistance genes appear, bacteria can pass them to offspring. They can also share them with other bacteria through horizontal gene transfer, or HGT. The three main HGT methods are transformation, conjugation, and transduction. Resistance genes are often carried on plasmids or transposons, which can move easily between cells and spread new resistance traits quickly.

Antibiotic overuse and misuse have made this problem worse. Using antibiotics for viral infections or to increase livestock growth can select for resistant bacteria. The susceptible bacteria die, while resistant survivors keep dividing and passing on the same trait. Over time, this can lead to multi-resistant bacteria, or superbugs, and may leave fewer treatment options for bacterial infections.

Antibiotic Resistance in Cloning

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antibiotic selection

Antibiotic resistance genes help scientists find bacteria that took up a plasmid with a gene of interest. In genetic engineering, this resistance is used as a marker, not just as a medical concern. The same process also connects to the growing problem of resistant bacteria in the real world. Antibiotics, such as penicillin, stop bacterial growth or kill bacteria. When bacteria naturally have, or are engineered to carry, an antibiotic resistance gene, the antibiotic no longer works on them.

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reproductive cloning

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genomics

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key terms and concepts

Learn how antibiotic resistance genes help scientists select transformed bacteria, and why resistance and superbugs are a major health concern.

Antibiotic Resistance in Cloning | JoVE K12

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Deoxyribonucleic acid, or DNA, is the genetic material responsible for passing traits from generation to generation in all organisms and most ...

DNA Packaging

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Eukaryotes have large genomes compared to prokaryotes. In order to fit their genomes into a cell, eukaryotes must pack their DNA tightly inside ...

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Types of RNA

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Transcription

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Translation

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Antibiotic Resistance in Cloning

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