Re: Going to buy the Tissue Culture kit
JoeReal is right about the mushrooms. I asked my friend why they do it, and it's to keep the plant true to type for commercial purposes. If you're selling under a brand name, your customers expect the same each time they purchase.
What I found out about the PPM is they put a small amount of sterile water/antibiotic/chlorine mix on top of the media when using new plants from other sources. The amounts I still haven't been able to find out, but it sounds like a very tiny bit.
I also found out that you use the apical meristem (undifferentiated tissue at the microscopic tip of a shoot/ root) because it is not yet joined to the donor plants vascular system. You are literally getting the cells before they can become contaminated by the donor plant. By doing this and proper sterilization of plant material to be used, there is not much need for PPM.
Now with that being said, I have not tried to do tc myself and there may be some reason why you would need a PPM.
When talking to my friend today, he told me to get the media, my jars, the donor plants and bring it over. He is not only going to show me how to do it, he said he'd do the first batch! I kinda want to wait until we get close to our first freeze before I pull any plants up though (mid 80's here today!). He also told me how to build a HEPA flow cabinet for about $150, and that you'll really appreciate not breathing all the bleach and alcohol that you get from a still air cabinet such as the aquarium I was going to use.
Let me know how it's going and I'll try to gain all the knowledge I can to pass along in this thread.