Your best bet is not to do your study in the field. Do it in a pest-free
greenhouse using as sterile a technique as possible; At least if you manage
to "purify" by autoclaving your soil, it has a better chance of staying that
way. Even better is not using soil at all if you wish to look at specific
microorganisms (their functions, plant symbiosis,etc.)---use vermiculite or
other substance perhaps mixed with sand and autoclave this planting media.
Then add an autoclaved nutrient solution, and your pure culture. Experiment
with medias and nutrient solutions to get your pH, etc correct for your
plants and/or your microbes.
We use this system to study nitrogen fixation by Rhizobium.
D. Jones, USDA/ARS
David Hagerberg wrote in message
>I'm working with fieldstudies of fungal and bacterial activity in soil.
>Now I would like to keep soil bacterium-free and fungus-free
>respectively in order to study the pure fungal or bacterial activity.
>This seems to be tricky and my first thoughts involve addition of
>specific antibiotics, however I doubt they will stay in my soil-samples
>for any longer period of time.
>Has anybody some suggestion how to keep soil free from bacteria and fungi
respectively?
