Alcoholic Fermentation: Second Edition, 1914Harden, Arthur
Science
Alcoholic Fermentation: Second Edition, 1914
Harden, Arthur
Fermentation
Some other explanation must therefore be sought for this phenomenon.
Great significance must be attached in this connection to the relation
noted above between the degree of disintegration and disorganisation
of the cell and the fall in the normal rate of fermentation. It seems
not impossible that fermentation may be associated in the living cell
with some special structure, or carried on in some special portion
of the cell, perhaps the nuclear vacuole described by Janssens and
Leblanc [1898], Wager [1898, 1911; Wager and Peniston, 1910] and
others which undergoes remarkable changes both during fermentation
and autofermentation [Harden and Rowland, 1901]. The disorganisation
of the cell might lead to many modifications of the conditions,
among others to the dilution of the various catalytic agents by
diffusion throughout the whole volume of the cell. As a matter of
observation the dilution of yeast-juice leads to a considerable
diminution of the rate of fermentation of sugar, and it is possible
that this is one of the chief factors concerned. That phenomena
of this kind may be involved is shown by the remarkable effect of
toluene on the autofermentation of yeast. Whereas the fermentation
of sugar is greatly diminished by the action of toluene, the rate of
autofermentation, which is carried on at the expense of the glycogen
of the cell, is greatly increased. In a typical case, for example, the
autofermentation of 10 grams of yeast suspended in 20 c.c. of water
amounted to 28 c.c. in 4·8 hours [p127] at 25°, whereas the same
amount of yeast in presence of 2 c.c. of toluene gave 97·6 c.c. in
the same time.
Many salts produce a similar effect on English top yeasts (in which
the autofermentation is large) [Harden and Paine, 1912], whereas
Neuberg and Karczag in Berlin [1911, 2] were unable to observe this
phenomenon.
A necessary preliminary of the fermentation of glycogen is its
conversion by a diastatic enzyme into a fermentable sugar, and it
is probable that the effect of the disorganisation of the cell by
toluene is that this enzyme finds more ready access to the glycogen,
which is stored in the plasma of the cell. No such acceleration
of autofermentation is effected by the addition of toluene to
yeast-juice, and hence the result is not due to an acceleration of the
action of the diastatic enzyme on the glycogen.
This effect of toluene is similar in character to the action of
anæsthetics on the leaves of many plants containing glucosides and
enzymes, whereby an immediate decomposition of the glucoside is
initiated [see H. E. and E. F. Armstrong, 1910].
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