Selection of Source of Enzymes

Selection of source:

As we already know that enzymes are the biological catalyst synthesized by the living cells that bring about chemical reactions concerned with life. Enzymes are complex protein molecules.It is proved that enzymes continued to function or bring out catalyst when they are separated from the cell in vitro. Normally enzymes are nontoxic and biodegradable .First of all to produce the enzyme industrially in a large amount we have to choose or select the source of an enzyme from which we can produce a large amount of enzyme.Enzyme source selection is the first and most important step in the production of the enzyme. The source should be selected in such a way that ;

• The quantity of production of enzyme should be high
• It should be easy to isolation,purification and in cost factor,
• Extraction of enzyme should be easy and don not contain any risk of contamination,
• It should be easy to manipulate,
• The source from which enzymes are produced must produce maximum quantities of desired enzymes in the short period of time .
• The metabolic produced must be less,
• Once the organism is selected ,strain improvement for the optimization of enzyme production can be done easily,

So the selection of source plays the vital role in the production of the enzyme. In the commercial production of enzymes, microbial strains are utilized since many centuries without knowing them fully. The first enzyme to cure the digestive disordered of a fungal amylase was taka-diastase 1896,in US..There are different types of source of are used to produce enzymes . Many years ago the German scientist demonstrated that extracts from animal organs (pancreases from pig and cow) can be used as the source of enzymes ,protease for the leather softening in 1905.The utilization of protease for the laundry purpose was started in 1915. Although it is beneficial it has the adverse effect also so it was not continued due to its allergic reactions of impurities in enzymes. Nowadays an especial and advanced techniques are available for the manufacture of enzymes without any allergic reactions. Basically, enzymes can be produced from a wide range of biological source and the great majority of them (80%) is the microbial sources.

The different organisms and their relative contribution to the production of enzymes commercially are :

Fungi-60%

Bacteria-24%

Yeast - 4%

Streptomyces-2%

Higher animals-6%

Higher plants-4%

In the early days ,animal and plant sources are largely selected for the enzyme production. Even now they are the major source of certain enzymes. Animal organs and tissues are used to the production of various enzymes such as lipase,esterases and proteases and they are the good source of enzymes. The enzyme lysozyme is mostly obtained from hen eggs.Some plants are also the good sources of enzymes like papain from papaya, bromelain from pineapple.

Limitations of animals and plants as the source of enzymes:

There are several limitations or failure associated with the production of enzymes from animals and plants source. For the commercial application of enzymes, its should be produced in the large amount but the quantity of enzymes produced by animal and plants are limited and there is a wide variation in their distribution. The most important drawback with plant and animal sources are in isolation,purification and in the cost factor. For example the extraction of industrial enzymes from bovine sources,there is a great risk of contamination with bovine spongiform encephalopathy. For this reason, the animal and plant source are not commercially used are a microbial production of enzymes are preferred .

There is a possibility of production of enzymes directly by mammalian cell cultures.But the main difficulties in this process is extremely high cost. However ,some therapeutic enzymes like tissue plasminogen activator are produced by cell cultures.

Microorganisms as the main source of enzyme:

Enzymes are the proteins which are called biological catalyst due to their ability or capacity to promote reactions more quickly and more efficiently .They bind to the substrate in a specific manner due to the presence of active site where the molecules of the enzymes most have high specificity with the molecules of the substrate.There are several industrial sectors where the enzymes from microorganismsare produced for specific applications. Biological active enzymes can be extracted from different sources of living organisms. But nowadays microorganisms are being an attractive source of enzymes as they can be cultured in large quantities in a relatively short period of time by the established method of fermentation using sophisticated tools. However, the level of production of the enzyme or the method of production of enzymes varies from different microorganisms and also the enzymes differ in their composition and properties. Microorganisms of closely related strains have enzymes with nearly similar properties ,while unrelated organism,s have totally different system .

The most critical feature of the microorganisms for the production of enzyme commercially or industrially significant enzymes is due to their GRAS ie; Generally Regarded as Safe status,which implies that they are non-toxic, nonpathogenic,and generally does not produce excess byproducts like antibiotics.There are generally less than 50 bacteria and fungi which are GRAS listed. Bacteria including subtitles,B.licheniformis and various other bacilli,lactobacilli,Streptomyces sps ,the yeast Saccharomyces cerevisiae,and the filamentous fungi b Bacillus belonging to the genera Aspergillus,Mucor, Rhizopus etc are the example of such type organisms.

Since Aspergillus, cultures are frequently inoculated with conidia. Most of the enzyme in bulky form are secreted by microorganisms directly into the culture medium but some enzymes like penicillin amylase and glucose isomerase are intracellular. The organisms are preferred which gives high yields of enzymes in shortest possible fermentation time. The advantages of microorganisms as enzyme source are summarized in following points:

• They are generally cheaper to produce as they can be produced in higher quantity,
• These enzymes content are more predictable and controlable,
• Plants and animal tissue contain potentially harmful materials and microbes including phenolic compound, endogenous enzyme inhibitor etc.
• Microorganisms have rapid growth rate compared to plants and animals,
• They can be genetically manipulated to produce enzyme of need .
• Enzymes obtained via microbial source are greater in volume.
• They produce wide variety of enzymes,
• They can be made to produce enzymes over wide environmental condition.