Nick Maclaren wrote:

Andy Burns wrote:

Apparently the 'true' ginger beer plant is not just yeast, but a
symbiotic mixture of a particular rare yeast and a bacteria ...

Nuts. That's about as likely as the claims that true bread, sourdough,
ale or lager yeast is something in particular.

Kew gardens seemed to agree [archived article]

https://web.archive.org/web/20121021090019/http://www.kew.org/plant-cultures/plants/ginger_food_ginger_beer_plant.html

When made in open conditions, such mixtures evolve to be whatever is
appropriate for the particular location, feedstock and growing
method.

Yes, I'm sure all manner of organisms would 'want' to incorporate into
the plant if it was conducive to them, but the claim seems to be that
Saccharomyces pyriformis and Brevibacterium vermiforme are the
characteristic pair.