I watched a few minutes, his statement that a flagella must rotate is wrong, they don't need to rotate and do not, so far as I am aware, actually rotate. What they do instead, which is difficult to describe, is have a rotating wave travel along a non rotating hair like part. Just as a linear wave on water moves across the surface of the water without the water itself moving along, so a rotating wave can traverse an otherwise stationary hair / rope etc. You can demonstrate this by attaching a rope to a tree, holding the rope, pulling it fairly tight and moving your hand in a circle. The result will be a circular wave traveling along the rope. The rope itself will not be rotating.
I gave up after that, I don't trust the guy.
The flagella actually do rotate. A famous and definitive experiment proved this a couple of decades ago by fixing a single flagellum to a glass slide, and a microscope video showed that the bacterium rotates instead.
Interesting. I am claiming they don't based on a documentary that clearly showed they don't rotate, and described as I have done. Unfortunately the documentary was many years ago and I don't imagine I could find it. I've no Idea what to search for.
Ok, for me I'm going to consider this an open question pending further information.
There are plenty of modern, well informed discussions on the bacterial motor on line. It is a very complex machine, and all the evidence suggests that it evolved only once, as the machinery is common to all bacteria (with flagella) that have been carefully investigated.
Ok, I'm too tired now, I'll investigate another day.
Thank you, I'm both surprised and intrigued by this.
Incidentally, the motor is also reversible, under control of the bacterium sensory apparatus, so they can "back out of" or steer away from unfavorable environments!
Good, comprehensive lecture here: https://www.youtube.com/watch?v=UKkBmyjJHnM
Mentioned in the link you provided. Fix the flagellum and the bacteria rotates.
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