phuongtl_phuongbacltd
New Member
" UNIT 51 : GENERAL PRINCIPLES FOR INDUSTRIAL PRODUCTION OF MICROBIAL
EXTRACELLULAR ENZYMES
Very little specific information has been presented in the public domain that details the particular
methods applied to the production of any one enzyme. This is largely due to the extremely competitive
state of enzyme production and marketing resulting in very real differences in the way each producer
arrives at a cost-effective process for his products.
There are some main steps of enzyme production as follow:
1. The Production Strain
Some principal microorganisms that have found acceptance for production of industrial enzymes.
The species listed are generally considered to present the least risk of toxin production during
fermentation as well as being non-pathogenic to man.
Bacillus species are comparatively easy to isolate and despite the problems associated with spore
formation, many have been isolated as non-sporing strains. The Aspergilli are similarly placed amongst
the fungi, although the formation of conidial spores is desirable for the ease of inoculation of large-scale
fermentations. In every case, the strain selected for production will have a highly improved enzyme
producing capability compared with the wild strains and will have undergone stringent screening to
ensure that it does not produce toxins or antibiotics in order to meet increasingly stringent standards for
food applications of enzyme product.
2. Fermentation
The choice of fermentation method lies between ‘solid state’ (which is also called semi-solid) and
submerged or ‘deep’ fermentation. In rare cases the organism will dictate the choice by virtue of either
non-production or low yields by one method. Generally, however, the nature of the final enzyme product
and its designated performance objective determine the method. Enzymes from solid state cultivation are
generally found to be complex mixtures, often including amylase, protease, lipase and non-starch
carbonhydrases in definite proportions that are regulated by the cultivation. If a high level of a single
activity is desired, it is commonly produced by submerged fermentation.
Submerged ‘deep’ fermentation has been adopted as the most economic route for the preparation of
bulk industrial enzymes. Suspended insoluble nutrients and inexpensive additional sources of nitrogen,
phosphate and trace elements in soluble forms are used. The medium selected must support good growth
of the microorganism and be as inexpensive as possible. Soybean meal, starch hydrolysates and corn
steep liquor dominate the list of typical ingredients. The specific additional growth the enzyme synthesis
stimulating requirements are determined for each organism selected as a production strain.
Despite great developments of sophisticated instrument monitoring of research fermentations, the
industrial enzyme fermentation system utilizes basic but large fermentation equipment. Main vessels can
reach 150 m3 in practice and they are an essential feature of the economics of bulk processing. Controls to
monitor pH, temperature and in some cases dissolved oxygen, are typical. Where the use of suspended
medium is encountered, it is often necessary to have efficient foam detection and antifoam treatment as an
extra control facility. Bulk medium is generally prepared separately in tanks that allow pH adjustment and
direct or heat exchange steam sterilization. Most systems pump the sterile medium into the fermentation
vessels that have been previously sterilized with live steam.
3. Broth Purification
The bran extract or fermentation broth contain the enzyme, residues of the suspended medium
components, the soluble medium components and the cells of the fermented microorganism. Initially, the
solids are removed by filtration or centrifugation aided by the use of flocculents to increase the particle size,
e.g. calcium salts, polyelectrolytes and aluminum salts typified by modern water treatment methods. It is
common to load a proportion of diatomaceous earth or other filter aid into the stirred broth before filtration,
which is most often performed on rotary vacuum filters. Where centrifugation is adopted, the high-speed
disc machine with continuous operation is preferred.
Concentration of enzyme liquids is a compromise between energy efficiency and activity loss. Low
temperature vacuum evaporation is most commonly applied to stable enzymes and ultrafiltration is used
for the more sensitive products, since it can successfully be performed at temperatures around 5 oC.
Purification is usually necessary both to eliminate microorganisms and to reduce the preparation to
the lowest practical contamination with other enzymes produced by the fermentation. Polishing and germ
filtration steps are able to remove microorganisms and a series of precipitations may be performed to
select the desired enzyme. The addition of an inorganic salt such as sodium or ammonium sulfate to a
specified concentration will precipitate a range of proteins which may include the desired enzyme or
leave it in the soluble phase. Further solution and precipitation stages may be performed with different
concentrations of precipitant to achieve a desired purification. Organic solvents that lower the dielectric
constant of the system and so reduce the solubility of proteins are also used to precipitate enzymes. The
most effective treatments are performed using chilled solvents and adding them to the aqueous broth,
whose pH has been adjusted to the isoelectric value for the enzyme being processed.
Purified liquid enzymes are standardized by dilution and the diluents generally include stabilizing
salts, polyalcohols or sugars and any permitted preservatives deemed necessary. In the limited
applications where a dry enzyme product is required, it is now recognized that the spray drying should
include a granulation to minimize the potential hazards of dusty, dry products. The inhalation of any
protein dust is likely to increase the risk of allergic response to further exposures to the same protein and
it is recommended to take full precautions when handling enzymes in powder form. Granulation will follow standardization with acceptable materials such as sugars, starch, flour or inorganic salts.
-----
Thank mọi người nhiều
EXTRACELLULAR ENZYMES
Very little specific information has been presented in the public domain that details the particular
methods applied to the production of any one enzyme. This is largely due to the extremely competitive
state of enzyme production and marketing resulting in very real differences in the way each producer
arrives at a cost-effective process for his products.
There are some main steps of enzyme production as follow:
1. The Production Strain
Some principal microorganisms that have found acceptance for production of industrial enzymes.
The species listed are generally considered to present the least risk of toxin production during
fermentation as well as being non-pathogenic to man.
Bacillus species are comparatively easy to isolate and despite the problems associated with spore
formation, many have been isolated as non-sporing strains. The Aspergilli are similarly placed amongst
the fungi, although the formation of conidial spores is desirable for the ease of inoculation of large-scale
fermentations. In every case, the strain selected for production will have a highly improved enzyme
producing capability compared with the wild strains and will have undergone stringent screening to
ensure that it does not produce toxins or antibiotics in order to meet increasingly stringent standards for
food applications of enzyme product.
2. Fermentation
The choice of fermentation method lies between ‘solid state’ (which is also called semi-solid) and
submerged or ‘deep’ fermentation. In rare cases the organism will dictate the choice by virtue of either
non-production or low yields by one method. Generally, however, the nature of the final enzyme product
and its designated performance objective determine the method. Enzymes from solid state cultivation are
generally found to be complex mixtures, often including amylase, protease, lipase and non-starch
carbonhydrases in definite proportions that are regulated by the cultivation. If a high level of a single
activity is desired, it is commonly produced by submerged fermentation.
Submerged ‘deep’ fermentation has been adopted as the most economic route for the preparation of
bulk industrial enzymes. Suspended insoluble nutrients and inexpensive additional sources of nitrogen,
phosphate and trace elements in soluble forms are used. The medium selected must support good growth
of the microorganism and be as inexpensive as possible. Soybean meal, starch hydrolysates and corn
steep liquor dominate the list of typical ingredients. The specific additional growth the enzyme synthesis
stimulating requirements are determined for each organism selected as a production strain.
Despite great developments of sophisticated instrument monitoring of research fermentations, the
industrial enzyme fermentation system utilizes basic but large fermentation equipment. Main vessels can
reach 150 m3 in practice and they are an essential feature of the economics of bulk processing. Controls to
monitor pH, temperature and in some cases dissolved oxygen, are typical. Where the use of suspended
medium is encountered, it is often necessary to have efficient foam detection and antifoam treatment as an
extra control facility. Bulk medium is generally prepared separately in tanks that allow pH adjustment and
You must be registered for see links
74direct or heat exchange steam sterilization. Most systems pump the sterile medium into the fermentation
vessels that have been previously sterilized with live steam.
3. Broth Purification
The bran extract or fermentation broth contain the enzyme, residues of the suspended medium
components, the soluble medium components and the cells of the fermented microorganism. Initially, the
solids are removed by filtration or centrifugation aided by the use of flocculents to increase the particle size,
e.g. calcium salts, polyelectrolytes and aluminum salts typified by modern water treatment methods. It is
common to load a proportion of diatomaceous earth or other filter aid into the stirred broth before filtration,
which is most often performed on rotary vacuum filters. Where centrifugation is adopted, the high-speed
disc machine with continuous operation is preferred.
Concentration of enzyme liquids is a compromise between energy efficiency and activity loss. Low
temperature vacuum evaporation is most commonly applied to stable enzymes and ultrafiltration is used
for the more sensitive products, since it can successfully be performed at temperatures around 5 oC.
Purification is usually necessary both to eliminate microorganisms and to reduce the preparation to
the lowest practical contamination with other enzymes produced by the fermentation. Polishing and germ
filtration steps are able to remove microorganisms and a series of precipitations may be performed to
select the desired enzyme. The addition of an inorganic salt such as sodium or ammonium sulfate to a
specified concentration will precipitate a range of proteins which may include the desired enzyme or
leave it in the soluble phase. Further solution and precipitation stages may be performed with different
concentrations of precipitant to achieve a desired purification. Organic solvents that lower the dielectric
constant of the system and so reduce the solubility of proteins are also used to precipitate enzymes. The
most effective treatments are performed using chilled solvents and adding them to the aqueous broth,
whose pH has been adjusted to the isoelectric value for the enzyme being processed.
Purified liquid enzymes are standardized by dilution and the diluents generally include stabilizing
salts, polyalcohols or sugars and any permitted preservatives deemed necessary. In the limited
applications where a dry enzyme product is required, it is now recognized that the spray drying should
include a granulation to minimize the potential hazards of dusty, dry products. The inhalation of any
protein dust is likely to increase the risk of allergic response to further exposures to the same protein and
it is recommended to take full precautions when handling enzymes in powder form. Granulation will follow standardization with acceptable materials such as sugars, starch, flour or inorganic salts.
-----
Thank mọi người nhiều