[allmendream]

The ability to digest citrate was cloned into the non citrate metabolizing e.coli by introducing plasmids that made the necessary enzymes.

This is quite different than e.coli evolving the ability on its own. The difference between writing a new book and being given an already existing book to read. People said no “new book” could be written using evolutionary means, yet such has been demonstrated. The existence of a different book with the same “message” doesn't discount the fact that this was indeed a “new book” written by an evolving strain of e.coli; not an existing book given to e.coli by way of a plasmid.

From the paper....

The inability of Escherichia coli to utilize citrate as the sole carbon and energy source has been recognized for 60 years and provides the basis for an often-used distinction between Cit- E. coli and many similar but Cit+ bacterial species.

[Sopater]

The very next sentence says:

The recent discovery of naturally occurring plasmids that confer a Cit+ phenotype on E. coli strains (14, 15, 35) has provided an explanation for the periodic isolation of bacteria that would have been called E. coli except for their ability to utilize citrate.

So the only reason that these other bacteria are NOT called "E. coli" is due to their ability to utilize citrate.

You continue to amaze me.