C:N Ratio and ammonia production

Lesley Robertson l.a.robertson at stm.tudelft.nl
Tue Oct 19 08:57:22 EST 1999


Alan S. Wicks <NAP-4 at worldnet.att.net> wrote in message
news:380B8C21.360BCDCE at worldnet.att.net...
> Greetings,
>
> We recently grew a bacterium in liquid meida using Difco
> Tryptic Soy Broth.  When we harvested the bacteria we
> noticed that there was a smell of free ammonia.
>
> Does this indicate that perhaps there was not enough CHO
> source in the media?  If this were a compost pile that would
> be the problem.
>
> Any ideas?

A lot depends on what the bug was, the growth conditions, and the medium
constituent concentrations (I can't remember the last time I used a
non-defined medium, so don't know the ingredients), but it SOUNDS like
dissimilatory nitrate reduction - happens when some fermentative bacteria
aren't getting enough oxygen and there's nothing in the medium to ferment so
they reduce nitrate to ammonium and excrete it (don't confuse this with
assimilatory nitrate reduction) as a survival mechanism. If you're growing
them aerobically, either shake/stir harder, or dilute your medium so that
you don't get anaerobic zones.
Lesley Robertson
Delft.





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