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:
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 |
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