Re: Vitamin B12

>From: Craig Bingman <cbingman at netcom_com>
>Subject: Re: Cobalt in fertilizer

>Hmmm.  My impression is that all life is dependent on vitamin B-12, which
>contains cobalt, and that it is only synthesized by procaryotes.  If
>anyone has information indicating that plants can either roll their own
>B-12 or are not dependent on it, I would be most interested to see it.
>I don't know if N-fixing organisms have additional requirements for
>cobalt.  I am aware that nitrogenases require either Mo or V, and other
>things like iron that are required by all life.
The information about cobalt and plants came from Biology of Plants, 5th.
ed., by Raven, Evert, and Eichorn, 1992, p. 596.  I looked up vitamin B12
in General and Comparative Physiology, 1983, by William S. Hoar, who says
(p.417) that a need for it is not known in all animals, but it is needed by
some protozoans and the higher vertebrates.  The author speculates,
however, that more animals will be found to need B12 because its role in
the higher vertebrates is connected with DNA synthesis.

Paul Krombholz                  Tougaloo College, Tougaloo, MS  39174
In 75 degree Jackson, Mississippi, where we are wondering what happened to