There are other symbiotic microorganisms which humans make use of. For example sourdough bread is made with a "starter" which contains wild yeasts and lactobacteria, instead of shop-bought yeast. Just like the ginger beer plant, you keep your starter and feed it so it grows. When it has doubled in size you can take part of it to leaven some bread. As well as making the bread rise, the starter gives the bread a unique tangy taste.
As far as I know, there is only one authentic ginger beer plant. But there are many sourdough starters, with different qualities. I am trying to get hold of a couple to compare them, but I may try to make my own from scratch later today. Watch this space.