• Question: Is in vivo gene cloning of plasmids of bacteria a realistic solution to make antibiotics more useful against bacteria, despite the fact that many bacteria have actually developed resistance against antibiotics?

    Asked by MaximDis to Daniela ?, ☣ Danna, Jonny, Juan, Lindsay on 16 Jun 2016.
    • Photo: Daniela Lobo

      Daniela Lobo answered on 16 Jun 2016:

      Hi again MaximDis,

      Well, plasmids are bits of circular bacterial DNA that often contain information not related to the bacteria basic life functions. It’s on these plasmids that the bacteria have, for example, the information of being or not antibiotic resistant (this is actually very important for molecular biology lab techniques – for example, if I only want to select bacteria that are resistant to a certain antibiotic, I add that same antibiotic to the foodie of the bacteria, and the bacteria that don’t have the resistance piece of DNA against that antibiotic, die, leaving only alive the bacteria I previously wanted to select). The interesting part is that some bacteria can transfer this information to other bacteria, making them also resistant to the antibiotic. Also, you can “synthetically” introduce this resistance: the virus I work with also has bits of information on its DNA that allows for antibiotic resistance (I made that on the lab, the virus doesn’t naturally have the antibiotic resistance bit on its DNA!). When the virus infects the bacteria, its DNA mixes with DNA from the bacteria, and the bacteria now gains a new power: becomes resistant to a certain antibiotic.
      I am not sure if this answers your question, let me know if this wasn’t clear.

    • Photo: Danna Gifford

      Danna Gifford answered on 16 Jun 2016:

      Hello MaximDis,

      I don’t think gene cloning on plasmids will make antibiotics more useful against bacteria. Let’s say you put a gene on a plasmid that made the bacteria susceptible to antibiotics again.
      You then treat the bacteria with the antibiotic you made them susceptible to, thus “punishing” the bacteria with the plasmid, because if they have the plasmid, they will die.
      Every time a bacterium divides, there is a chance that a copy of the plasmid won’t make it into the new cell.
      So now you have a bacterium without the plasmid, that can then grow when the antibiotic is present.
      There is a strong natural selection force for losing the plasmid when the antibiotic is present, hence the bacteria will evolve to lose the plasmid you gave them to make them susceptible to the antibiotic.

    • Photo: Jonathan Hunter

      Jonathan Hunter answered on 16 Jun 2016:

      Sorry, this is not my field but I think the others have made excellent points!

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