At
about
this
time
Liebig
the
German
chemist,
had
claimed
that
fermentation
and
putrefaction
were
processes
caused
by
the
chemical
instability
of
organic
molecules.
On
the
other
hand,
Pasteur
had
shown
that
living
yeast
cells
were
required
for
the
conversion
of
sugar
into
alcohol
and
had
suggested
that
these
fermentations,
and
transformations
are
brought
about
by
the
agency
of
microorganisms.
At
this
time.
the
distilleries
in
France,
where
alcohol
was
produced
from
sugar
beet
had
difficulties
in
their
fermentations
and
requested
Pasteur
for
help.
Pasteur
found
that
the
trouble
was
due
to
the
replacement
of
the
alcoholic
fermentation
by
a
lactic
fermentation.
Instead
of
finding
yeast
in
the
fermenting
brew,
he
found
rod-shaped
structures.
He
concluded
that
these
rod
shaped
organisms
were
responsible
for
the
conversion
of
sugar
into
lactic
acid.
Subsequently,
he
also
showed
that
different
fermentations
are
brought
about
by
specific
microorganisms.
