Michael Tanabe , Professor of Plant Science, U. of Hawaii at Hilo, College of Agriculture, Forestry and Natural Resource Management writes:

My responsibilities at UHH-CAFNRM include directing a Certificate of Achievement in Plant Tissue Culture program, teaching 4 courses in the area of plant tissue culture and plant propagation and conducting research pertaining to micropropagation of especially tropical and subtropical plants.

Contamination is frequently the greatest concern for many labs in the State of Hawaii. Our year-round comfortable weather is great for attracting tourists but also for growth of microbes. As such, the plant TC lab is frequently challenged to develop disinfection protocols that maintain asepsis from initial explanting to growth in the culture growth room. This problem is compounded in the teaching environment due to the broad range of techniques and attitudes that the students bring to the lab.

I decided to try [Plant Preservative Mixture] as a medium-incorporated biocide several years ago. Initially, I conducted a simple air test using FS M&S and nutrient agar with and without the recommended level of PPM. The media combinations were sterilized and exposed to the open air environment for 3 hours. Absolutely no growth of microbes was evident after the cultures were incubated at 29° C for 4 days. I was convinced that PPM had biocide activity so I incorporated it into culture media for various tropical plants to determine possible phytotoxic effects. No obvious phytotoxic effects such as chlorosis or necrosis were observed. Additionally, contamination from airborne contaminants in the culture storage room was significantly reduced.

All plants shown were grown in a medium containing 1-2 ml PPM™ per liter.
Click a thumbnail to view full size image.