Hi - long time since I've checked in here. I recently bumped into an article I thought was worth sharing: "Zing of the ginger beer: Rediscovering the lost fermentation of the 'super spice'" published in 2011 and appears to be from a food-industry journal in India.
It provides some history of ginger production, ginger beer itself, and a scientific history of the discovery of the microbes in the original ginger beer plant (GBP). The Instructables link about making your own beer from an authentic GBP link in the article is still active.
Another link provided leads to a German institute that is sort of a living "library" of microorganisms. The institute could be a valuable resource for those serious about pure cultures: although they no longer sell GBP grains, for 90 Euro you can order pure culture of Lentilactobacillus hilgardii, or you could go into production of acetic or citric acid by ordering from their strains for schools & universities.