PPM sells for $1 per ml. There should be a lot of better alternatives. Tissue Culture has been very successful long before PPM is. For one thing, there is a new invention that generates dissolved ozone in water and anything you rinse with the ozonized water practically become sterile on their surface contact. That machine is featured in one of the best inventions of the year, and its primary usage is for cleaning store-bought fruits and vegetables of pesticide, pests, and microbial contamination. It is called the Lotus Sanitizing System, but I think it can be used to soak your meristems or source material for initial decontamination:
http://www.time.com/time/2006/techgu...ns/meals4.html
The antibiotics that the makers of PPM are using, and if one is not careful, it could encourage the development of even stronger microbial contaminants. So limit its use or alternate with other methods of sterilization or use other antibiotic types. I am just worried that the use of such things will bring anew the viscious cycle of developing new antibiotics. The use of alcohol sprays, pressure cooker for sterilization are old reliable standard ways of sterilization without encouraging the microbial antibiotic's resistances. A nice enclosed hood with adjustable positive or negative pressure is a very good workbench for a lot of tissue culture. They are easy to build if these are pricey.
PPM appears to be a very expensive TC shortcut but in my opinion, it will not be doing us any favor in the long run. Practicing to be clean at each step, thinking of ways of minimizing contamination and accuracy in the measurements are some of the very good habits I have observed from a lot of my friends involved in TC. It also says that you will have to try various concentrations of PPM for each type of plant cultivar that you are trying to propagate, and that would be a lot of trials and expense.