Industrial applications
Enzymes are used in the chemical industry and other industrial
applications when extremely specific catalysts are required. However,
enzymes in general are limited in the number of reactions they have
evolved to catalyze and also by their lack of stability in organic solvents
and at high temperatures. Consequently, protein engineering is an active
area of research and involves attempts to create new enzymes with novel
properties, either through rational design or in vitro evolution.[70][71]
Application
Baking industry
Enzymes used
Uses
Fungal alpha-amylase
enzymes are normally
inactivated at about 50
degrees Celsius, but are
destroyed during the baking
process.
Catalyze breakdown of
starch in the flour to sugar.
Yeast action on sugar
produces carbon dioxide.
Used in production of white
bread, buns, and rolls.
Proteases
Biscuit manufacturers use
them to lower the protein
level of flour.
Trypsin
To predigest baby foods.
alpha-amylase catalyzes the release
of sugar monomers from starch
Baby foods
Brewing industry
They degrade starch and
Enzymes from barley are
proteins to produce simple
released during the mashing sugar, amino acids and
stage of beer production.
peptides that are used by
yeast for fermentation.
Widely used in the brewing
Industrially produced barley process to substitute for the
enzymes
natural enzymes found in
barley.
Germinating barley used for malt.
Amylase, glucanases,
proteases
Split polysaccharides and
proteins in the malt.
Betaglucanases and
Improve the wort and beer
arabinoxylanases
filtration characteristics.
Amyloglucosidase and
pullulanases
Low-calorie beer and
adjustment of fermentability.
Proteases
Remove cloudiness
produced during storage of
beers.
Acetolactatedecarboxylase
(ALDC)
Avoid the formation of
diacetyl
Fruit juices
Cellulases, pectinases
Clarify fruit juices
Dairy industry
Rennin, derived from the
stomachs of young ruminant Manufacture of cheese,
animals (like calves and
used to hydrolyze protein.
lambs).
Microbially produced
enzyme
Now finding increasing use
in the dairy industry.
Lipases
Is implemented during the
production of Roquefort
cheese to enhance the
ripening of the blue-mould
cheese.
Lactases
Break down lactose to
glucose and galactose.
Papain
To soften meat for cooking.
Amylases,
amyloglucosideases and
glucoamylases
Converts starch into glucose
and various syrups.
Roquefort cheese
Meat tenderizers
Starch industry
Glucose
Fructose
Glucose isomerase
Converts glucose into
fructose in production of
high fructose syrups from
starchy materials. These
syrups have enhanced
sweetening properties and
lower calorific values than
sucrose for the same level
of sweetness.
Paper industry
Amylases, Xylanases,
Cellulases and ligninases
Degrade starch to lower
viscosity, aiding sizing and
coating paper. Xylanases
reduce bleach required for
decolorising; cellulases
smooth fibers, enhance
water drainage, and
promote ink removal;
lipases reduce pitch and
lignin-degrading enzymes
remove lignin to soften
paper.
Cellulases
Used to break down
cellulose into sugars that
can be fermented (see
cellulosic ethanol).
Ligninases
Use of lignin waste
A paper mill in South Carolina.
Biofuel industry
Cellulose in 3D
Biological detergent
Used for presoak conditions
Primarily proteases,
and direct liquid applications
produced in an extracellular
helping with removal of
form from bacteria
protein stains from clothes.
Amylases
Detergents for machine dish
washing to remove resistant
starch residues.
Lipases
Used to assist in the
removal of fatty and oily
stains.
Cellulases
Used in biological fabric
conditioners.
Proteases
To remove proteins on
contact lens to prevent
infections.
Laundry soap
Contact lens cleaners
Rubber industry
Catalase
To generate oxygen from
peroxide to convert latex
into foam rubber.
Photographic industry
Protease (ficin)
Dissolve gelatin off scrap
film, allowing recovery of its
silver content.
Restriction enzymes, DNA
ligase and polymerases
Used to manipulate DNA in
genetic engineering,
important in pharmacology,
agriculture and medicine.
Essential for restriction
digestion and the
polymerase chain reaction.
Molecular biology is also
important in forensic
science.
Molecular biology
Part of the DNA double helix.
Enzymes in the environment
Enzymes perform a wide range of very important functions throughout nature. They
are highly specific and efficient, guiding the biochemistry of life with great precision
and fidelity. This fidelity is essential in the cells of living organisms, and a multitude
of mechanisms have evolved for controlling the activity of these enzymes themselves.
Enzymes play a key role in harvesting energy from the sun via photosynthesis,
perform a wide range of metabolic functions throughout every living cell in the bodies
of plants and animals, and are in fact really the catalysts of all biological processes
constituting life on earth.
Bacteria and fungi also contain enzymes that are essential to their survival in the
environment. These organisms live in a variety of habitats, some fairly moderate
(these organisms are called mesophiles) and others in extreme environments such as
hydrothermal vents, hot springs, and sulphataric fields (extremophiles). As
extremophiles have adapted to these extreme habitats, they produce enzymes
(biocatalysts) that are able to function under conditions that their mesophilic
counterparts are not able to tolerate, and therefore are highly exploitable in research
areas such as bioremediation and biocatalysis.
Detoxifying the environment
Biodegradation is the natural degradation of matter in the natural environment in the
absence of any human intervention. Bioremediation, in contrast, is characterised by
human intervention and is the technology of pollution treatment, using biological
systems to transform and convert various pollutant species in the environment to less
toxic or non-toxic forms. An effective bioremediation will produce harmless water
and carbon dioxide as the end products, which are then able to re-enter natural
ecosystems.
Tiny microorganisms such as bacteria are often the agents of choice for
bioremediation. Scientists at Rhodes University have successfully exploited the
sulphate reducing bacteria (SRB) and methanogenic producing bacteria (MPB) for
treatment of municipal primary sewage and acid mine drainage (AMD) wastes. Both
these bacterial populations dramatically increase the rate of hydrolysis of solid wastes
under anaerobic conditions, and are also able to work together in a very effective
manner: The high levels of sulphate and metals contained in acid mine drainage are
removed using SRB, while the sulphide produced by the SRB dramatically increases
the rate at which the MPB hydrolyses primary sludge.
Biocatalysis by extremophiles
Enzymes produced by extremophiles (bacteria and fungi living in harsh conditions)
are also highly exploitable in the biocatalytic industry. For example, thermophiles are
organisms that live under conditions of extreme high temperature. These produce
thermophilic enzymes that are readily exploited in industry, such as amylase,
xylanases used in paper bleaching, proteases used in baking, brewing and in
detergents, as well as DNA polymerase enzymes used in genetic engineering.
Psychrophilic enzymes are present in psychrophiles, organisms that have adapted to
very cold climates, such as those microorganisms living in the Artic and Antarctic
regions. The psychrophiles are used in cheese maturation and in the dairy industry
(e.g. proteases) and biosensors (e.g. dehydrogenases). Similarly, there are a host of
other enzymes that are acidophilic (tolerant to low pH), piezophilic (tolerant to high
pressure) and metalophilic (tolerant to high metal concentration). There is even a
bacterium, Deinococcus radiodurans, which is the most radiation-resistant organism
known and is recently being targeted and engineered for the bioremediation of
radioactive waste.
The sulphate reducing bacteria mentioned previously belong to the class of
acidophiles, as they are able to live in highly acidic environments in acid mine
drainage rich environments.
Monitoring the environment
These enzymes may have another important purpose - they can serve as indicators of
the "biochemical health" of the environment. Scientists can selectively target and
monitor certain molecules in nature which can help them keep track of environmental
pollution biodegradation and bioremediation processes in a particular system such as
a polluted river or in a waste recycling plant. This is a relative new field of research,
but already key molecules have been identified in nature that may provide a lot of
information regarding the "metabolic state" of a system.
For example, monitoring enzymes responsible for sulphate activation and reduction in
anaerobic bacteria living in marine and estuarine sediments can indicate the level of
metabolic activity (sulphate activation and reduction) that is occurring in these
sediments. At the Department of Biochemistry, Microbiology and Biotechnology at
Rhodes University, we are currently investigating enzymes and other biomolecules
which can potentially provide more information regarding the metabolic state of
natural systems, thereby monitoring the processes of bioremediation more effectively.
Novel metabolic pathways in nature
Although metabolic pathways in nature have for the most part been well studied and
characterised, there are still many pathways that exist in nature that are poorly
understood. At Rhodes, scientists are focusing efforts on the natural biodegradative
processes at work in nature that are responsible for the cleavage of complex aromatic
compounds.
There is still much to learn from enzymes, as they continuously surprise scientists
with their remarkable adaptability to extreme conditions. As a result of increasingly
more recalcitrant chemical pollutants finding their way into the environment,
microorganisms, and the enzymes they possess, have to constantly adapt in order to
deal with the presence of the pollutants. Microorganisms either respond by
implementing and optimising existing metabolic reaction pathways in their genetic
make-up to degrade harsh chemical poolutants, or they develop new pathways,
degrading these compounds into non-toxic components or elements that can be
reassimilated for their own cellular metabolism and survival.
SUGAR SYRUPS FROM STARCH Environmental Benefits: Reduced use of strong
acids and bases, reduced energy consumption (less greenhouse gas), less corrosive
waste, and safer production environment for workers.
DAIRY APPLICATIONS Environmental Benefit: Cheese makers are no longer
dependent upon enzymes recovered from slaughtered calves, kids and lambs for
production of rennet needed for most cheese making. Based on current demand for
chymosin, commercial needs for rennet could not be met from animal sources.
CLEAR CLEAR FRUIT JUICE Environmental Benefit: The use of enzymes in juice
processing helps assure that the maximum amount of juice is removed from the fruit,
thereby reducing
waste and controlling costs.
MEAT TENDERIZING Environmental benefits: Less waste, better use of raw
materials.
CONFECTIONS Environmental Benefit: Enzymes replace hydrochloric acid in the
manufacturing process, thereby eliminating the need for harsh chemical
processing and thereby reducing risk to the environment. Elimination of a strong
acid also provides a safer workplace.
LOWER TEMPERATURE & NO PHOSPHATE CLOTHES Environmental
Benefits: Reduced phosphate load to rivers and lakes. Reduced energy consumption
with lower temperature washing.
ETHANOL FUEL FROM RENEWABLE Environmental benefit: Greater utilization
of natural, renewable resources, safer factory working conditions, reduced harmful
auto emissions.
LEATHER TANNING DEHAIRING BATING Environmental Benefits: Lower
chemical load to waste system. Lower odor during processing,
DEGREASING OF LEATHER Environmental Benefits: Replaces solvent-based
system, lowers volatile organic chemical load.
PAPER INDUSTRY Environmental Benefits: Less chlorine bleach, therefore less
chlorinated organics in the waste stream.
DEINKING OF WASTE PAPER Environmental Benefits: Improved deinking creates
more opportunity for recycled paper, less chemical discharge to waste streams, less
wash water use, decreased load on landfills and a better utilization of natural
resources.