Katherine D Sauer wrote:
> I'm attempting to grow Methanosaeta concilii,
> and I can't seem to get the medium right. I
> tried using the medium described in the paper
> which characterized the strain GP6 (which I have),
> by Patel 1984. I followed the protocol, and got
> a large quantity of black precipitate after
> making sterile additions. The protocol said to
> add NaHCO3, vitamins, and FeCl2 aseptically
> after autoclaving. Before these additions (but
> after autoclaving), the medium was clear.
> I suspect it is FeS that is precipitating.
Methanogens need iron, but not as much iron as is often
included in their culture media. It was once
demonstrated (I believe in the 1970's) that large
concentrations of iron enhanced methanogenesis and the
growth of methanogenic bacteria, but this apparent iron
requirement was later revealed to be a requirement for
nickel, a trace contaminant of the iron. If you use a
trace metal solution that satisfies other requirements
of Methanosaeta concilii, the amount of iron needed will
not visibly precipitate ferrous sulfide.
Methanosaeta concilii is difficult to grow without large
(e.g., 10%) inocula. Even larger inocula (as high as
50%) will give you more dependable growth.
--
David R. Boone
Professor of Environmental Microbiology
Oregon Graduate Institute, Portland
503-690-1146
boone at ese.ogi.eduhttp://www.ese.ogi.edu/ese_docs/boone.html
