axenic cultures

[JMB113 at psuvm.psu.edu]

Hello, I have been culturing diatom algae and have had trouble with
bacterial contaminants for some time now.  I have tried to clean the algae
using mixtures of penicillin, streptomycin, and chloramphenicol, but any
concentrations that kill the bacteria also kill the algae.  Shorter term
exposures are ineffective.  I do not know what species of bacteria I have,
but I do know that it is gram negative.  Does anyone have any suggestions as
to other agents that may be effective for removing gram-negative
contaminants without killing my diatoms?

Thanks,  Joe Balczon
         Graduate Program in Ecology
         Penn State University