Excellent video. What would be even more powerful is if they repeated the experiment, but with the 1000x agar right next to the antibiotic-free medium to illustrate what happens when antibiotics are used properly.
I would like to see that as well, but I would want them to let it sit for a long time - months, maybe. Because eventually, you may still get a mutation that can withstand the jump from 0 to 1000x.
Quite possible, especially because there's a safe haven of antibiotic-free medium just across the border, and the likelihood of a beneficial mutation is correlated with the number of individuals present.
In a properly-applied therapeutic situation, there is no such safe haven, and one hopes that the subject's immune system would be able to exterminate the much smaller load once the antibiotic's done its job, instead of leaving any stragglers behind to develop resistance.
Without iterative improvement, the chance of a complex adaption occurring by random chance are much much smaller. I don't know how complex an adaption to become resistant to this substance is, so it's possible it could occur by random chance. But even if so, it would likely still take much longer.
I can't speak about what the adaptation is, so I don't know if the adaptations at the difference levels of concentration are different in kind or degree. If degree, it is more feasible. Certainly the environment is only different in degree. Keep in mind the adaptation to go from 0 to 10x did not happen iteratively - and I may be remembering wrong, but I think that the bacteria stopped at the 10x boundary longer than the others. That may indicate that the subsequent mutations were of degree, not kind. Anyway, I think it would be worth doing this experiment.
