Microorganisms
Nutritional
Classification -Although organisms can be grouped based on their relationship to molecular oxygen, they can also be grouped in relation to their nutritional requirements.
Broadly
two
groups
are
recognized.
(i)
Autotrophs
- which
can
utilize,
inorganic
nutrients
or
light
as
a
source
of
energy,
e.g.
nitrifying
bacteria,
algae,
etc.,
and
(ii)
Heterotrophs
- which
require
organic
compounds
as
a
source
of
energy,
e.g.
many
bacteria,
fungi
and
protozoa.
Although
this
classification
is
relatively
simple
it
does
not
allow
us
to
distinguish
organisms
based
on
their
energy
requirement
and
the
principal
carbon
source.
