2179_EnzyEnv by gegeshandong


									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                     Enzymes used                        Uses

                                      Fungal alpha-amylase          Catalyze breakdown of
                                      enzymes are normally          starch in the flour to sugar.
                                      inactivated at about 50       Yeast action on sugar
Baking industry                       degrees Celsius, but are      produces carbon dioxide.
                                      destroyed during the baking   Used in production of white
                                      process.                      bread, buns, and rolls.
alpha-amylase catalyzes the release
of sugar monomers from starch
                                                                    Biscuit manufacturers use
                                      Proteases                     them to lower the protein
                                                                    level of flour.

Baby foods                            Trypsin                       To predigest baby foods.

                                                                    They degrade starch and
                                      Enzymes from barley are
                                                                    proteins to produce simple
                                      released during the
                                                                    sugar, amino acids and
Brewing industry                      mashing stage of beer
                                                                    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

                                      Amylase, glucanases,          Split polysaccharides and
Germinating barley used for malt.     proteases                     proteins in the malt.

                                      Betaglucanases and            Improve the wort and beer
                              arabinoxylanases            filtration characteristics.

                              Amyloglucosidase and        Low-calorie beer and
                              pullulanases                adjustment of fermentability.

                                                          Remove cloudiness
                              Proteases                   produced during storage of

                              Acetolactatedecarboxylase   Avoid the formation of
                              (ALDC)                      diacetyl

Fruit juices                  Cellulases, pectinases      Clarify fruit juices

                              Rennin, derived from the
                              stomachs of young ruminant Manufacture of cheese,
                              animals (like calves and   used to hydrolyze protein.
Dairy industry                lambs).

                              Microbially produced        Now finding increasing use
                              enzyme                      in the dairy industry.

                                                          Is implemented during the
                                                          production of Roquefort
                              Lipases                     cheese to enhance the
                                                          ripening of the blue-mould
Roquefort cheese

                                                          Break down lactose to
                                                          glucose and galactose.

Meat tenderizers              Papain                      To soften meat for cooking.

                                                          Converts starch into
                              amyloglucosideases and
                                                          glucose and various syrups.
Starch industry

                                                          Converts glucose into
Glucose            Fructose
                                                          fructose in production of
                              Glucose isomerase
                                                          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                                                  Degrade starch to lower
                                                                viscosity, aiding sizing and
                                                                coating paper. Xylanases
                                                                reduce bleach required for
                                                                decolorising; cellulases
                                  Amylases, Xylanases,          smooth fibers, enhance
                                  Cellulases and ligninases     water drainage, and
                                                                promote ink removal;
                                                                lipases reduce pitch and
                                                                lignin-degrading enzymes
                                                                remove lignin to soften
A paper mill in South Carolina.                                 paper.

                                                                Used to break down
                                                                cellulose into sugars that
Biofuel industry                                                can be fermented (see
                                                                cellulosic ethanol).
Cellulose in 3D

                                  Ligninases                    Use of lignin waste

                                                               Used for presoak conditions
                                  Primarily proteases,
                                                               and direct liquid applications
                                  produced in an extracellular
                                                               helping with removal of
                                  form from bacteria
Biological detergent                                           protein stains from clothes.

                                                                Detergents for machine dish
                                  Amylases                      washing to remove resistant
                                                                starch residues.

                                                                Used to assist in the
                                  Lipases                       removal of fatty and oily
Laundry soap

                                                                Used in biological fabric

                                                                To remove proteins on
Contact lens cleaners             Proteases                     contact lens to prevent
                                                              To generate oxygen from
Rubber industry                   Catalase                    peroxide to convert latex
                                                              into foam rubber.

                                                              Dissolve gelatin off scrap
Photographic industry             Protease (ficin)            film, allowing recovery of its
                                                              silver content.

                                                              Used to manipulate DNA in
                                                              genetic engineering,
                                                              important in pharmacology,
Molecular biology                                             agriculture and medicine.
                                  Restriction enzymes, DNA    Essential for restriction
                                  ligase and polymerases      digestion and the
Part of the DNA double helix.                                 polymerase chain reaction.
                                                              Molecular biology is also
                                                              important in forensic

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

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

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

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.

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.

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

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