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Enzyme Classification According To Their Sources

  Biologically active enzymes may be extracted from any living organism. A very wide range of sources are used for commercial enzyme production from Actinoplanes to Zymomonas, from spinach to snake venom. Of the hundred or so enzymes being used industrially, over a half are from fungi and yeast and over a third are from bacteria with the remainder divided between animal (8%) and plant (4%) sources (Table 1). A very much larger number of enzymes find use in chemical analysis and clinical diagnosis. Non-microbial sources provide a larger proportion of these, at the present time. Microbes are preferred to plants and animals as sources of enzymes because:

  1. they are generally cheaper to produce.
  2. their enzyme contents are more predictable and controllable,
  3. reliable supplies of raw material of constant composition are more easily arranged, and
  4. plant and animal tissues contain more potentially harmful materials than microbes, including phenolic compounds (from plants), endogenous enzyme inhibitors and proteases.

  Attempts are being made to overcome some of these difficulties by the use of animal and plant cell culture.

Table 1. Some important industrial enzymes and their sources.

Enzyme

EC numberb

Source

Intra/extra
-cellular
c

Scale of productiond

Industrial  use

 Animal enzymes

 

 

 

 

Catalase

1.11.1.6

Liver

  I

  -

Food;milk,cheese, egg beverages,  salads

Lipasee

3.1.1.3

Pancreas

  E 

  -

Food;cheese,fats and oil

Rennetf

3.4.23.4

Abomasum

  E

  +

Cheese

 Plant enzymes

 

 

 

 

Actinidin

3.4.22.14

Kiwi fruit

  E

  -

Food

a-Amylase

3.2.1.1

Malted barley

  E

  +++

Brewing

b-Amylase

3.2.1.2

Malted barley

  E

  +++

Brewing

Bromelain

3.4.22.4

Pineapple latex

  E

   -

Brewing

b-Glucanaseg

 3.2.1.6

Malted barley

  E 

  ++

Brewing

Ficin

3.4.22.3

Fig latex

  E

  -

Food

Lipoxygenase

1.13.11.12

Soybeans

 I

  -

Food

Papain

3.4.22.2

Pawpaw latex

  E

  ++

Meat

 Bacterial enzymes

 

 

 

 

a-Amylase

3.2.1.1

Bacillus

  E

  +++

Starch,Fats and Oils, Cheese, Beverages, Bakery,

b-Amylase

3.2.1.2

Bacillus

  E

  +

Starch,Beverages

Endo-b-glucanase

3.2.1.6

Bacillus

 

 

Beverages

Glucose isomeraseh

                 5.3.1.5

 

 

                   Bacillus

 

 

  I

 

 

  ++

 

 

Fructose syrup   Cereal and Starch, Fruit and Vegetables, Beverages, Sugar and Honey

Hemicellulase

3.2.1.78

Bacillus

 

 

Cocoa,chocolate,coffee and tea

Proteasei

3.4.21.14

Bacillus

  E

  +++

Meat, Fish, Soups and Broths

Pullulanasej

3.2.1.41

Klebsiella

  E

  -

Starch, Sugar and Honey, Beverages

 Fungal enzymes

 

 

 

 

a-Amylase

3.2.1.1

Aspergillus

  E

  ++

Bakery; cereal and starch; fruit and vegetable; beverages; sugar and honey

Tannase

3.1.1.20

Aspergillus

 

 

Beverages

Glucoamylasek

3.2.1.3

Aspergillus

  E

  +++

Starch;fruit and vegetable;beverage; sugar and honey; confectionery; bakery; dietary foods

Catalase

1.11.1.6

Aspergillus

  I

  -

Food;milk;cheese; egg;salads; beverages

Cellulase

3.2.1.4

Trichoderma

  E

  -

Waste; fruit and vegetables; beverages;dietary foods

Dextranase

3.2.1.11

Penicillium

  E

  -

Food;sugar and honey

Glucose oxidase

1.1.3.4

Aspergillus

  I

  -

Food;egg;beverages; salads

Lactasel

3.2.1.23

Aspergillus

  E

  -

Dairy;milk;cheese;edible ice;dietary foods

Lipasee

3.1.1.3

Rhizopus

  E

  -

Food;cheese;fats and oils

Rennetm

3.4.23.6

Mucor miehei

  E

  ++

Cheese

Pectinasen

3.2.1.15

Aspergillus

  E

  ++

Drinks;fats and oils;fruit and vegetables;fish

Pectin lyase

4.2.2.10

Aspergillus

  E

  -

Drinks

Proteasem

3.4.23.6

Aspergillus

  E

  +

Baking

Raffinaseo

3.2.1.22

Mortierella

  I

  -

Food;beverages

 Yeast enzymes

 

 

 

 

 

Invertasep

3.2.1.26

Saccharomyces

  I/E 

  -

Confectionery

Lactasel

3.2.1.23

Kluyveromyces

  I/E

 -

Dairy;milk;cheese;edible ice;dietary foods

Lipasee

3.1.1.3

Candida

  E

  -

Food;cheese;fats and oils

Raffinaseo

3.2.1.22

Saccharomyces

  I

  -

Food;sugar and honey

 

 

a The names in common usage are given. As most industrial enzymes consist of mixtures of enzymes, these names may vary from the recommended names of their principal component. Where appropriate, the recommended names of this principal component is given below.

b The EC number of the principal component.

c I - intracellular enzyme; E - extracellular enzyme.

d +++ > 100 ton year-1; ++ > 10 ton year-1; + > 1 ton year-1; - < 1 ton year-1.

e triacylglycerol lipase; 

f chymosin;

g Endo-1,3(4)-b-glucanase;

h xylose isomerase;

i subtilisin;

j a-dextrin endo-1,6-a-glucosidase;

k glucan 1,4-a-glucosidase;

l b-galactosidase;

m microbial aspartic proteinase;

n polygalacturonase;

o a-galactosidase;

p b-fructofuranosidase.

 

  In practice, the great majority of microbial enzymes come from a very limited number of genera, of which Aspergillus species, Bacillus species and Kluyveromyces (also called Saccharomyces) species predominate. Most of the strains used have either been employed by the food industry for many years or have been derived from such strains by mutation and selection. There are very few examples of the industrial use of enzymes having been developed for one task. Shining examples of such developments are the production of high fructose syrup using glucose isomerase and the use of pullulanase in starch hydrolysis.

  Producers of industrial enzymes and their customers will share the common aims of economy, effectiveness and safety. They will wish to have high-yielding strains of microbes which make the enzyme constitutively and secrete it into their growth medium (extracellular enzymes). If the enzyme is not produced constitutively, induction must be rapid and inexpensive. Producers will aim to use strains of microbe that are known to be generally safe. Users will pay little regard to the way in which the enzyme is produced but will insist on having preparations that have a known activity and keep that activity for extended periods, stored at room temperature or with routine refrigeration. They will pay little attention to the purity of the enzyme preparation provided that it does not contain materials (enzymes or not) that interfere with their process. Both producers and users will wish to have the enzymes in forms that present minimal hazard to those handling them or consuming their product.

  The development of commercial enzymes is a specialised business which is usually undertaken by a handful of companies which have high skills in

  1. screening for new and improved enzymes,
  2. fermentation for enzyme production,
  3. large scale enzyme purifications,
  4. formulation of enzymes for sale,
  5. customer liaison, and
  6. dealing with the regulatory authorities.