JoeReal

the meristem are equivalent to the "eyes" on potatoes, but instead on potatoes, these are located around the banana corms, you can easily spot them after you clean up the corm of roots, soil and dirt.

PPM, isn't that concentration abbrev. for parts per million? If you can reduce contamination to less than parts per million, then your kitchen hood would be sterile enough for tissue culture. But anyway, it is Plant Preservative Mixture biocide, just don't know what kind.