need help with nutrients for bacteria !

Franz H. Wagner franz.wagner at
Tue Nov 23 15:18:30 EST 1999

I am working on experiments with enriching natural streamwater (surface
water) with nutrients (glucose, nitrate, phosphate) to test the effect
on surface attached bacteria (biofilms). My problem is, that whem I am
adding a concentrated nutrient solution to the stream water the
phosphate (sodium phoshate x 12 H2O) is immediately falling out in form
of "flocks". It appears under the microscope that these flocks have a
particular center - a cristal or a bacteria probably ? Filtering the
water (0.01 mm) does not help.
The same thing is NOT happening if I dissolve the nutrients in tap water
or destilled water.
Does anybody of you have an idea what I should do ? Is there another
phosphate which would do the job better ? Could the bacteria use NaHPO4
as well (better soluble - no flocks) ?
Sorry for my bad english and for my un-knowledge in chemistry and
microbiology. I am not a microbiologist myself, but a
limnologist-zoologist - and I do these experiments to see which effect
the influenced biofilms may have on invertebrates living in streams.

Thanks in advance for any help and suggestion


Franz H. Wagner, Biological Station Lunz
3293 Lunz am See, AUSTRIA
TEL: ++7486 8095 24 FAX: ++7486 8095 31
e-mail: franz.wagner at

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