> A typical E. coli cell, after all, measures about one micrometer across.

Bit nitpicky here but ... he wrote a typical E. coli cell.

Naturally bacteria have different size ranges, depending on many factors - nutrients, temperature, genome and so forth; e. g. look at how huge Thiomargarita namibiensis is.

But the 1 µm as average here given for E. coli, is not correct:

https://bionumbers.hms.harvard.edu/bionumber.aspx?id=117344&...

Length 1.78±0.54 μm

So while +/- at the lower end may be 1.24 µm, the max range here would be 2.42 µm, which is what I had more in mind (e. g. roughly about 2µm). I don't have all of the data to be able to say which is the exact value, but I think the website at bionumbers.hms.harvard.ed is more realistic, so I would say that E. coli's best average is more at 2µm than 1µm.