Yeah I think it’s a great question and I don’t know that I have a great answer. Plasmids (small rings of DNA that float around separately) are part of the story. My understanding here is pretty sketchy, but I think plasmids are way more likely to be deleted than the chromosomal DNA, and for some reason antibiotic resistant genes tend to be in plasmids (perhaps because they are shared so frequently through horizontal gene transfer)? So the “delete within a few hours” bit is probably overstating the average case of DNA deletion in bacteria. I would be surprised if it “knew” about the function of the gene, although I agree it seems possible that some epigenetic mechanism could explain it. I don’t know of any, though!
Thanks!!
Yeah I think it’s a great question and I don’t know that I have a great answer. Plasmids (small rings of DNA that float around separately) are part of the story. My understanding here is pretty sketchy, but I think plasmids are way more likely to be deleted than the chromosomal DNA, and for some reason antibiotic resistant genes tend to be in plasmids (perhaps because they are shared so frequently through horizontal gene transfer)? So the “delete within a few hours” bit is probably overstating the average case of DNA deletion in bacteria. I would be surprised if it “knew” about the function of the gene, although I agree it seems possible that some epigenetic mechanism could explain it. I don’t know of any, though!