Plasmid Copy number(low vs. High) and affect on evolution rate

[siena248]

Hello,

 

I was curious about low, medium, and high copy plasmids and how their copy number affects the rate of evolution.

 

I am learning about antibiotic resistance and we are talking about specifically when there is no selective pressure of antibiotics, how quickly will a bacteria lose the plasmid conferring for antibiotic resistance when it does not have a selective advantage.

 

We are looking at three different types of plasmids, low, medium and high copy number. The reasoning I thought of is that for the low copy plasmid, it will lose the plasmid conferring antibiotic resistance quickly when there is no selective pressure to save energy when making the plasmids. And then I was thinking for the high copy plasmid it would be vice versa, and the medium somewhere in between.

 

Does this make sense?

 

Thank you!

[CharonY]

 

The reasoning I thought of is that for the low copy plasmid, it will lose the plasmid conferring antibiotic resistance quickly when there is no selective pressure to save energy when making the plasmids.

 

Can you elaborate on this part. What do you mean with energy saving in that context?

[siena248]

 

Can you elaborate on this part. What do you mean with energy saving in that context?

I mean that since it has a low amount number of copies, losing one plasmid when it is not advantageous will save energy/cost in terms of the cell. I'm not sure if it makes any sense.

 

Thank you!

[CharonY]

So if you think about energy cost, isn't maintaining high copy plasmids more costly? If you think about your answers you have actually two somewhat separate elements to consider.