cyanobacterial contaminants

Mon Aug 17 12:31:18 EST 1998

Dear Microbiologists,

I am growing ttwo types of moss crusts on sand trays, with the purpose of 
testing the resultant crusts in a wind tunnel. Of necessity the trays are 
large..2m by 30cm.  In total I have 3reps of each moss...and plan to test 
the ability of moss protonema to withstand wind erosion.  unfortunately , 
despite my best efforts, I have a cyanobacterial contaminant... probably a 
species of Nostoc, ( which is a good sand binder) . The sand was autoclaved 
for 50mins in a shallow pan. The deionized water  also runs through a U/V 
light system. All equipment was sterilized or where appropriate washed down 
with a strong soln of Chlorox.  The trays are in a large plastic tent and 
misted at regular intervals.

One of the mosses is Pohlia which prefers an acdic environment, so I can 
spray with a medium which is pH 3.5. This seems to inhibit the Nostoc.
The other moss is Tortula, whch dies at a similar pH.

I was thinking of treating the Tortula crust with Streptomycin, until I 
found out that it is stable, but also toxic to humans. There is a lot of 
dust generated in the wind tunnel and I am afraid of causing problems to 
the people who work there now and in the future!

Does anyone know of an antibiotic that is not particularly stable but is 
effective against cyanobacteria?  or alternatively does anyone have any 
suggestions ?

Any help would be gratefully welcomed.


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