PPM™ significantly simplifies the tissue culture working procedures as follows:
1. Media containing PPM™ may be dispensed outside the laminar flow hood (LFH) exposed to the ambient air. The plates should be covered soon after agar solidification. In the event that media dispensing is done by a pump, we recommend passing autoclaved hot water through the hoses prior to and after media dispensing.
2. Heat sensitive or heat stable liquid media containing PPM™ does not need to be sterilized by Millipore filters or autoclaved provided that it will be stored in sterile containers and that the stock solutions are not contaminated. In rich media containing 200 mg/liter or more of amino acids or proteins, it is recommended to filter the media with the PPM™.
3. If working in the LFH the utensils (forceps or scalpels) do not need to be flamed. They should be periodically dipped in 70% alcohol. The LFH does not need to be certified and the work can be done as well outside the LFH on a clean surface for a period not exceeding 1 hour.
4. PPM™ is an acidic liquid solution (pH 3.8). PPM™ should be stored at 4°C. (see Safety Information below). At the recommended dose of 0.05 - 0.2% (v/v), PPM™ is added to the medium before or after autoclavation to prevent airborne and endogenous contamination at low inoculum densities.
5. PPM™ is less effective when exposed to high density of bacteria or fungi spores found regularly on seed's coat. For in vitro germination, seeds should be conventionally surface sterilized with EPA registered bleach. Therefore, in the presence of PPM™ (in the germination medium), the seeds can be rinsed under tap water in a non-sterile strainer and left to dry preferably in the LFH. If the utensil ends have touched active bacteria, fungi culture or otherwise suspected of being contaminated, they should be sterilized by autoclave or by use of an electric heating element.