Methanogenic
Bacteria
Methanogenic
bacteria
may
have
been
among
the
earliest
living
organisms
on
earth
because they
can
grow
autotrophically
(chemo
autotrophs)
on
hydrogen
and
carbon
dioxide
under
anaerobic
conditions
and
it
is
presumed
that
the
early
atmosphere
of
the
earth
would
have
permitted
the
growth
of
just
such
organisms.
Methanogens
can
be
differentiated
on
the
basis
of
relatively
few
morphological
and
physiological
features
