History of Enzymes
The history of modern enzyme technology really began in 1874
when the Danish chemist Christian Hansen produced the first specimen
of rennet by extracting dried calves' stomachs with saline solution.
Apparently this was the first enzyme preparation of relatively
high purity used for industrial purposes.
This significant event had been preceded by a lengthy evolution.
Enzymes have been used by man throughout the ages, either in the
form of vegetables rich in enzymes, or in the form of microorganisms
used for a variety of purposes, for instance in brewing processes,
in baking, and in the production of alcohol. It is generally known
that enzymes were already used in the production of cheese since
old times.
Even though the action of enzymes has been recognised and enzymes
have been used throughout history, it was quite recently that
their importance were realised. Enzymatic processes, particularly
fermentation, were the focus of numerous studies in the 19th century
and many valuable discoveries in this field were made. A particularly
important experiment was the isolation of the enzyme complex from
malt by Payen and Persoz in 1833. This extract, like malt itself,
converts gelatinised starch into sugars, primarily into maltose,
and was termed 'diastase'.
Development progressed during the following decades, particularly
in the field of fermentation where the achievements by Schwann,
Liebig, Pasteur and Kuhne were of the greatest importance. The
dispute between Liebig and Pasteur concerning the fermentation
process caused much heated debate. Liebig claimed that fermentation
resulted from chemical process and that yeast was a nonviable
substance continuously in the process of breaking down. Pasteur,
on the other hand, argued that fermentation did not occur unless
viable organisms were present.
The dispute was finally settled in 1897, after the death of both
adversaries, when the Buchner brothers demonstrated that cell
free yeast extract could convert glucose into ethanol and carbon
dioxide just like viable yeast cells. In other words, the conversion
was not ascribable to yeast cells as such, but to their nonviable
enzymes.
In 1876, William Kuhne proposed that the name 'enzyme' be used
as the new term to denote phenomena previously known as 'unorganised
ferments', that is, ferments isolated from the viable organisms
in which they were formed. The word itself means 'in yeast' and
is derived from the Greek 'en' meaning 'in', and 'zyme' meaning
'yeast' or 'leaven'.
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Early developments in
Japan
During the early part of this century, enzyme technology was
also developing slowly but surely outside Europe. In the Far East,
an age-old tradition prevailed where mould fungi, the so-called
koji, were (and still are) used in the production of certain foodstuffs
and flavour additives based on soya protein (shoyu, miso, tempeh)
and fermented beverages (sake, alcohol). Koji is prepared from
steamed rice into which a mixture of mould fungi is inoculated,
the composition of the mixture being passed down from generation
to generation. This formed the basis which the Japanese scientist
Takamine developed a fermentation process for the industrial production
of fungal amylase; the process included the culture of Aspergillus
oryzae on moist rice or wheat bran. The product was called 'Takadiastase'
and it is still used as a digestive aid. The method of fermentation
suggested by Takamine, the 'surface culture' or 'semisolid
culture’ is still actively used in the production of various
enzymes.
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Textile Desizing
At about the same time as Takamine was developing his novel fermentation
technique, another field was being opened up for the use of enzymes
- the desizing of textiles. Previously, textiles were treated
with acid, alkali or oxidising agents, or soaked in water for
several days so that naturally occurring microorganisms could
break down the starch. However, both of these methods were difficult
to control and sometimes damaged or discoloured the material.
It represented great progress, therefore, when crude enzyme extracts
in the form of malt extract, or later, in the form of pancreas
extract, were first used to carry out desizing.
Bacterial amylase derived from Bacillus subtilis was used for
desizing, the first time by Boidin and Effront as early as 1917.
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Leather Bating
Investigations carried out by the German chemist and industrial
magnate Otto Rohm before World War I were of great importance
for the further development of the industrial use of enzymes.
Among other things, he studied the so called 'bating' process,
a step in the preparation of hides and skins prior to tanning.
According to tradition, bating required the excrement of dogs
and pigeons, a fact that did not improve the image of tanning
which was considered a stinking and unpleasant activity. Rohm's
theory was that these excrements exerted their effect because
they contained residual amounts of the animals' digestive enzymes.
If this was so, it might be possible to use extracts of the pancreas
directly for bating. Such extracts were tried and produced the
expected positive results. Naturally, Rohm accepted this as confirmation
of the correctness of his theory, but later experiments showed
that it was not the animals' enzymes that were active, but rather
enzymes of bacteria growing in the intestinal tract.
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The first detergent enzyme
Parallel to his studies of the problems involved in tanning,
Rohm investigated other processes where enzymes would prove even
more valuable. Nevertheless, his efforts were not to score a success
until 50 years later. Rohm actually developed the first method
for washing protein stained cloth in detergents containing enzymes
and manufactured the first detergent preparation containing enzymes.
The enzyme preparation used was pancreatin (extracted from pancreatic
glands), which contains the protein degrading enzyme trypsin.
Breakthrough in detergents was made in 1959, when a Swiss chemist
Dr. Jaag, developed a new product called Bio 40 containing a bacterial
protease instead of trypsin.
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Sugars from starch
A very important field in which enzymes have proved to be of
great value over the last 15-20 years is the starch industry.
In 1950s, fungal amylase was used in the manufacture of specific
types of syrup, i.e., those containing a range of sugars, which
could not be produced by conventional acid hydrolysis. The real
turning point was reached early in the 1960s when an enzyme glucoamylase,
was launched for the first time, which could completely break
down starch into glucose. Within a few years, almost all glucose
production was reorganised and enzyme hydrolysis was used
instead of acid hydrolysis because of the more benefits such as
greater yield, higher degree of purity and easier crystallisation.
The process was further improved by the introduction of a new
technique used for the enzymatic pre-treatment (liquefaction)
of starch by using a heat-stable alpha amylase.
Years of research in biochemistry and biotechnology have boosted
knowledge of enzymes for industries as well as research. Many
new techniques have been established to modify enzymes or increase
their yields. New techniques for purification of enzymes are constantly
developing and so are being discovered new application of enzymes
in medicine, research and industries.
The success and importance of using enzymes in a variety of modern
industrial processes is illustrated by the applications described
under Enzymes section
